Add support for Python 3.8.7

Closes @W-7791264@.
Release v186 (#1124 )
2026-06-05 23:10:16 +00:00 · 2020-11-20 11:49:34 +00:00 · 2020-11-18 13:26:39 +00:00 · 2020-11-17 15:19:48 +00:00 · 2020-11-13 13:10:52 +00:00 · 2020-11-12 18:40:31 +00:00
141 changed files with 1446 additions and 3368 deletions
@@ -0,0 +1,6 @@
 {
  "productTag": "a1aB0000000MR0RIAW",
  "issueTypeLabels": { "gus: story": "USER STORY", "gus: bug": "BUG P3" },
  "defaultBuild": "Heroku Unscheduled",
  "statusWhenClosed": "CLOSED"
 }
@@ -1 +1 @@
-* @heroku/languages
+* @heroku/languages
@@ -0,0 +1,15 @@
 version: 2
 updates:
  - package-ecosystem: "pip"
    directory: "/"
    schedule:
      interval: "weekly"
    labels:
      - "c: dependencies"
  - package-ecosystem: "bundler"
    directory: "/"
    schedule:
      interval: "weekly"
    labels:
      - "c: dependencies"
@@ -1,12 +1,17 @@
 name: Check Changelog
-on: [pull_request]
+on:
  pull_request:
    types: [opened, reopened, edited, synchronize]
 jobs:
- build:
+  check:
-   runs-on: ubuntu-latest
+    runs-on: ubuntu-latest
-   steps:
+    if: |
-   - uses: actions/checkout@v1
+      !contains(github.event.pull_request.body, '[skip changelog]') &&
-   - name: Check that CHANGELOG is touched
+      !contains(github.event.pull_request.body, '[changelog skip]') &&
-     run: |
+      !contains(github.event.pull_request.body, '[skip ci]')
-       cat $GITHUB_EVENT_PATH | jq .pull_request.title |  grep -i '\[\(\(changelog skip\)\|\(ci skip\)\)\]' ||  git diff remotes/origin/${{ github.base_ref }} --name-only | grep CHANGELOG.md
+    steps:
      - uses: actions/checkout@v1
      - name: Check that CHANGELOG is touched
        run: git diff remotes/origin/${{ github.base_ref }} --name-only | grep CHANGELOG.md
@@ -10,3 +10,5 @@ buildpack/*
 builds/dockerenv.staging*
 builds/dockerenv.production
 test/scratch
@@ -1,7 +0,0 @@
 repos:
 -   repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v2.3.0
    hooks:
    -   id: check-yaml
    -   id: end-of-file-fixer
    -   id: trailing-whitespace
@@ -1,39 +1,41 @@
-language: ruby
+language: minimal
-dist: trusty
+dist: focal
-sudo: required
+branches:
-
+  only:
-rvm:
+  - main
 - 2.4.4
 before_script:
  - gem install bundler -v 1.16.2
  - bundle exec hatchet ci:setup
 script:
-  - docker build --pull --tag travis-build-cedar-14 --file $(pwd)/builds/cedar-14.Dockerfile .
+  - make test STACK="${STACK}" TEST_CMD="${TEST_CMD}"
  - docker run --rm -e "STACK=cedar-14" -e "USE_STAGING_BINARIES=$USE_STAGING_BINARIES" travis-build-cedar-14 bash $TESTFOLDER
  - docker build --pull --tag travis-build-heroku-16 --file $(pwd)/builds/heroku-16.Dockerfile .
  - docker run --rm -e "STACK=heroku-16" -e "USE_STAGING_BINARIES=$USE_STAGING_BINARIES" travis-build-heroku-16 bash $TESTFOLDER
  - docker build --pull --tag travis-build-heroku-18 --file $(pwd)/builds/heroku-18.Dockerfile .
  - docker run --rm -e "STACK=heroku-18" -e "USE_STAGING_BINARIES=$USE_STAGING_BINARIES" travis-build-heroku-18 bash $TESTFOLDER
 jobs:
  include:
-  - stage: Bash linting (shellcheck)
+  - name: Bash linting (shellcheck)
    sudo: false
    script: make check
-  - stage: Hatchet Integration
+  - name: Hatchet integration tests
-    if: branch = master
+    if: env(HEROKU_API_USER) IS present AND env(HEROKU_API_KEY) IS present
-    name: Run Hatchet
+    language: ruby
-    script: "bundle exec rspec"
+    rvm:
      - 2.7
    before_script:
      - bundle exec hatchet ci:setup
    script:
      - PARALLEL_SPLIT_TEST_PROCESSES=11 bundle exec parallel_split_test spec/hatchet/
 env:
-  matrix:
+  jobs:
-    - TESTFOLDER=test/run-deps
+    - STACK=heroku-16 TEST_CMD=test/run-deps
-    - TESTFOLDER=test/run-versions
+    - STACK=heroku-16 TEST_CMD=test/run-versions
-    - TESTFOLDER=test/run-features
+    - STACK=heroku-16 TEST_CMD=test/run-features
    - STACK=heroku-18 TEST_CMD=test/run-deps
    - STACK=heroku-18 TEST_CMD=test/run-versions
    - STACK=heroku-18 TEST_CMD=test/run-features
    - STACK=heroku-20 TEST_CMD=test/run-deps
    - STACK=heroku-20 TEST_CMD=test/run-versions
    - STACK=heroku-20 TEST_CMD=test/run-features
  global:
    - HATCHET_RETRIES=3
    - IS_RUNNING_ON_CI=true
-    - HATCHET_APP_LIMIT=5
+    - HATCHET_APP_LIMIT=80
    - HATCHET_DEPLOY_STRATEGY=git
    - secure: yjtlPE5FbVxTKnjUy/tZUBgSEf4qADD3QOxtgziuid73S0U/1IEXlMGFULsQzIjtlHKmHeywZqpVVEpthIH4RuT7uoX1Pb7SSM/g0T8fT3VoEFbFK1uYl0oZQbUS4Klxv9tPiumj8if3m6ULEGIz1X0wZcMOC0tMLwVCnwmap0E=
    - secure: ZeFTHWwnpIKE9nAqs88ocmiQh7bKce84lilGm5J23nf3N6V4wNyLwqlkvsM008WGBCaOg9AUx7ZunasT0ANsR5gLP3eV2UUg7ILdRgV2Gy13eNRFheC4PHdN92RqQ3aKoqlIv2K999xlhVjod0NzhkQQXB6PddfQINbuU7ks6As=
@@ -1,35 +1,168 @@
 # Python Buildpack Changelog
-# Master
+## Unreleased
 - Python 3.8.7 is now available (CPython) (#1122).
 ## v186 (2020-11-18)
 - Update the `BUILD_WITH_GEO_LIBRARIES` error message (#1121).
 - Switch NLTK feature detection away from `sp-grep` (#1119).
 - Switch Django collectstatic feature detection away from `sp-grep` (#1119).
 - Remove vendored `sp-grep` script (#1119).
 - Remove vendored `pip-diff` script (#1118).
 - Remove vendored `pip-grep` script (#1116).
 ## v185 (2020-11-12)
 - Error if the unsupported `BUILD_WITH_GEO_LIBRARIES` env var is set (#1115).
 - Remove deprecated GDAL/GEOS/PROJ support (#1113).
 - Remove vendored `jq` binary (#1112).
 - Remove redundant Mercurial install step (#1111).
 - Remove support for the Cedar-14 stack (#1110).
 ## v184 (2020-10-21)
 - Vendor buildpack-stdlib instead of fetching from S3 (#1100).
 - Fix metric names for metrics emitted within `sub_env` (#1099).
 ## v183 (2020-10-12)
 - Add support for Heroku-20 (#968).
 ## v182 (2020-10-06)
 - Python 3.9.0 is now available (CPython) (#1090).
 - Migrate from the `lang-python` S3 bucket to `heroku-buildpack-python` (#1089).
 - Remove `vendor/shunit2` (#1086).
 - Replace `BUILDPACK_VENDOR_URL` and `USE_STAGING_BINARIES` with `BUILDPACK_S3_BASE_URL` (#1085).
 ## v181 (2020-09-29)
 - PyPy 2.7 and 3.6, version 7.3.2 are now available (Note: PyPy support is in beta) (#1081).
 ## v180 (2020-09-24)
 - Python 3.8.6 is now available (CPython) (#1072).
 ## v179 (2020-09-23)
 - Remove duplicate pipenv metric event (#1070).
 - Emit metrics for how the Python version was chosen for an app (#1069).
 - Emit Python version metric events for all builds, not just clean installs (#1066).
 ## v178 (2020-09-07)
 - Python 3.5.10 is now available (CPython) (#1062).
 ## v177 (2020-08-18)
 - Python 3.6.12 and 3.7.9 are now available (CPython) (#1054).
 - The default Python version for new apps is now 3.6.12 (previously 3.6.11) (#1054).
 ## v176 (2020-08-12)
 - Rebuild the Python 3.4.10 archives with the correct version of Python (#1048).
 - Fix the security update version check message for apps using PyPy (#1040).
 - Remove `vendor/test-utils` (#1043).
 ## v175 (2020-08-05)
 - Update pip from 20.0.2 to 20.1.1 for Python 2.7 and Python 3.5+ (#1030).
 - Update setuptools from 39.0.1 to: (#1024)
  - 44.1.1 for Python 2.7
  - 43.0.0 for Python 3.4
  - 47.1.1 for Python 3.5+
 - Switch the `heroku-buildpack-python` repository default branch from `master` to `main` (#1029).
 ## v174 (2020-07-30)
 - For repeat builds, also manage the installed versions of setuptools/wheel, rather than just that of pip (#1007).
 - Install an explicit version of wheel rather than the latest release at the time (#1007).
 - Output the installed version of pip, setuptools and wheel in the build log (#1007).
 - Errors installing pip/setuptools/wheel are now displayed in the build output and fail the build early (#1007).
 - Install pip using itself rather than `get-pip.py` (#1007).
 - Disable pip's version check + cache when installing pip/setuptools/wheel (#1007).
 - Install setuptools from PyPI rather than a vendored copy (#1007).
 - Reduce the number of environment variables exposed to `bin/{pre,post}_compile` and other subprocesses (#1011).
 ## v173 (2020-07-21)
 - Python 3.8.5 is now available (CPython).
 ## v172 (2020-07-17)
 - Python 3.8.4 is now available (CPython).
 ## v171 (2020-07-07)
 - Python 3.6.11 and 3.7.8 are now available (CPython).
 ## v170 (2020-05-19)
 - Python 2.7.18, 3.5.9, 3.7.7 and 3.8.3 are now available (CPython).
 - PyPy 2.7 and 3.6, version 7.3.1 are now available (Note: PyPy support is in beta).
 - Docs: Fix explanation of runtime.txt generation when using pipenv.
 - Bugfix: Correctly detect Python version when using a `python_version` of `3.8` in `Pipfile.lock`.
 ## v169 (2020-04-22)
 - Add a Hatchet test for python 3.8.2
 - Set Code Owners to @heroku/langauges
 - Bugfix: Caching on subsequent redeploys
 - Update tests to support latest version of Python
 ## v168 (2020-04-06)
 - Doc: Update Readme with version numbers
 - update Code Owners to include the Heroku Buildpack Maintainers team
 - Deprecation warning: `BUILD_WITH_GEO_LIBRARIES` is now deprecated. See warning for details.
 - Clean up build log output
 - Update Python versions in README to match docs
 - Django version detection fixed, link updated
 ## v167 (2020-03-26)
 - Add failcase for cache busting
 - Bugfix: Clearing pip dependencies
 ## v166 (2020-03-05)
 - Correct ftp to https in vendored file
 - Warn for Django 1.11 approaching EOL, provide link to roadmap
 ## v165 (2020-02-27)
 - Python 3.8.2 now available.
 ## v164 (2020-02-20)
 - Update requirements.txt builds to use Pip 20.0.2
 - Download get-pip.py to tmpdir instead of root dir
--------------------------------------------------------------------------------
+## v163 (2019-12-23)
 # 163 (2019-12-23)
 - New pythons released:
  Python 3.8.1, 3.7.6, 3.6.10 (CPython)
  Beta Release: Pypy 2.7 and 3.6, version 7.2.0
-# 162 (2019-12-06)
+## v162 (2019-12-06)
 - Bug fix: fragile sqlite3 install
-# 161 (2019-12-2)
+## v161 (2019-12-2)
 - Bug fix: Sqlite3 version bump
-# 160 (2019-10-23)
+## v160 (2019-10-23)
 - Bugfix: Pipenv no longer installs twice in CI
-# 159 (2019-10-22)
+## v159 (2019-10-22)
 - Python 2.7.17 now available on Heroku 18 and 16.
-# 158 (2019-10-21)
+## v158 (2019-10-21)
 - Python 3.7.5 and 3.8.0 now available on Heroku 18 and 16.
 - Add support for Python 3.8 branch
@@ -37,11 +170,11 @@
  - Test Improvements
 - Add support for staging binary testing
-# 157 (2019-09-18)
+## v157 (2019-09-18)
 - Typo fixes
-# 156 (2019-09-12)
+## v156 (2019-09-12)
 - Python 3.6.9 and 3.7.4 now available.
@@ -49,125 +182,125 @@
 - Build utility and documentation updates
 - Bump Hatchet tests to point at new default python version.
-# 155 (2019-08-22)
+## v155 (2019-08-22)
 add docs and make target for heroku-18 bob builds
-# 154 (2019-07-17)
+## v154 (2019-07-17)
 Fix python 3.5.7 formula actually building 3.7.2
-# 153 (2019-06-21)
+## v153 (2019-06-21)
 Hotfix for broken heroku-16 deploys
-# 152 (2019-04-04)
+## v152 (2019-04-04)
 Python 3.7.3 now available.
-# 151 (2019-03-21)
+## v151 (2019-03-21)
 Python 3.5.7 and 3.4.10 now available on all Heroku stacks.
-# 150 (2019-03-13)
+## v150 (2019-03-13)
 Python 2.7.16 now available on all Heroku stacks.
-# 149 (2019-03-04)
+## v149 (2019-03-04)
 Hotfix for broken Cedar 14 deploys
-# 148 (2019-02-21)
+## v148 (2019-02-21)
 No user facing changes, improving internal metrics
-# 147 (2019-02-07)
+## v147 (2019-02-07)
 Python 3.7.2 and 3.6.8 now available on all Heroku stacks.
-# 146 (2018-11-11)
+## v146 (2018-11-11)
 Python 3.7.1, 3.6.7, 3.5.6 and 3.4.9 now available on all Heroku stacks.
-# 145 (2018-11-08)
+## v145 (2018-11-08)
 Testing and tooling expanded to better support new runtimes
-# 144 (2018-10-10)
+## v144 (2018-10-10)
 Switch to cautious upgrade for Pipenv install to ensure the pinned pip version
 is used with Pipenv
-# 143 (2018-10-09)
+## v143 (2018-10-09)
-Add support for detecting SLUGIFY_USES_TEXT_UNIDECODE, which is required to
+Add support for detecting `SLUGIFY_USES_TEXT_UNIDECODE`, which is required to
 install Apache Airflow version 1.10 or higher.
-# 142 (2018-10-08)
+## v142 (2018-10-08)
 Improvements to Python install messaging
-# 139, 140, 141
+## v139, 140, 141
 No user-facing changes, documenting for version clarity
-# 138 (2018-08-01)
+## v138 (2018-08-01)
 Use stack image SQLite3 instead of vendoring
-# 137 (2018-07-17)
+## v137 (2018-07-17)
 Prevent 3.7.0 from appearing as unsupported in buildpack messaging.
-# 136 (2018-06-28)
+## v136 (2018-06-28)
 Upgrade to 3.6.6 and support 3.7.0 on all runtimes.
-# 135 (2018-05-29)
+## v135 (2018-05-29)
 Upgrade Pipenv to v2018.5.18.
-# 134 (2018-05-02)
+## v134 (2018-05-02)
 Default to 3.6.5, bugfixes.
-# 133
+## v133
 Fixes for Pip 10 release.
-# 132
+## v132
 Improve pip installation, with the release of v9.0.2.
-# 131
+## v131
 Fix bug with pip.
-# 130
+## v130
 Better upgrade strategy for pip.
-# 129
+## v129
 Don't upgrade pip (from v128).
-# 128
+## v128
 Upgrade pip, pin to Pipenv v11.8.2.
-# 127
+## v127
 Pin to Pipenv v11.7.1.
-# 126
+## v126
 Bugfixes.
-# 125
+## v125
 Bugfixes.
-# 124
+## v124
 Update buildpack to automatically install `[dev-packages]` during Heroku CI Pipenv builds.
@@ -176,101 +309,101 @@ Update buildpack to automatically install `[dev-packages]` during Heroku CI Pipe
 - No longer warn if there is no `Procfile`.
 - Update Pipenv's "3.6" runtime specifier to point to "3.6.4".
-# 123
+## v123
 Update gunicorn `init.d` script to allow overrides.
-# 122
+## v122
 Update default Python to v3.6.4.
-# 121
+## v121
 Update default Python to v3.6.3.
-# 120
+## v120
 Use `$ pipenv --deploy`.
-# 119
+## v119
 Improvements to Pipenv support, warning on unsupported Python versions.
 - We now warn when a user is not using latest 2.x or 3.x Python.
 - Heroku now supports `[requires]` `python_full_version` in addition to `python_version`.
-# 118
+## v118
 Improvements to Pipenv support.
-# 117
+## v117
 Bug fix.
-# 116
+## v116
 Vendoring improvements.
 - Geos libraries should work on Heroku-16 now.
 - The libffi/libmemcached vendoring step is now skipped on Heroku-16 (since they are installed in the base image).
-# 115
+## v115
 Revert a pull request.
 - No longer using `sub_env` for `pip install` step.
-# 114
+## v114
 - Bugfixes.
 Blacklisting `PYTHONHOME` and `PYTHONPATH` for older apps. Upgrades to nltk support.
-# 113
+## v113
 Updates to Pipenv support.
-# 112
+## v112
 Bugfix.
 - Fixed grep output bug.
-# 111
+## v111
 Linting, bugfixes.
-# 110
+## v110
 Update default Python to 3.6.2.
-# 109
+## v109
 Update Default Python to 3.6.1, bugfixes.
 - Fixed automatic pip uninstall of dependencies removed from requirements.txt.
-# 108
+## v108
 Fix output for collectstatic step.
-# 107
+## v107
 Bugfix for C dependency installation.
-# 106
+## v106
- Don't install packages that could mess up packaging.
+Don't install packages that could mess up packaging.
 - The Python buildpack will automatically remove `six`, `pyparsing`, `appdirs`,
   `setuptools`, and `distribute` from a `requirements.txt` file now, as these
   packages are provided by the Python buildpack.
- # 105
+## v105
- Improvements to output messaging.
+Improvements to output messaging.
-# 104
+## v104
 General improvements.
@@ -280,52 +413,52 @@ General improvements.
 [395]: https://github.com/heroku/heroku-buildpack-python/pull/395
-## 103
+## v103
 Bug fixes and improvements.
 - Fix for Pipenv.
 - Fix for Heroku CI.
- Improve handling of WEB_CONCURRENCY when using multiple buildpacks.
+- Improve handling of `WEB_CONCURRENCY` when using multiple buildpacks.
- Adjust environment variables set during the build to more closely match those in the dyno environment (DYNO is now available, STACK is not).
+- Adjust environment variables set during the build to more closely match those in the dyno environment (`DYNO` is now available, `STACK` is not).
 - Restore the build cache prior to running bin/pre_compile.
-## 102
+## v102
 Buildpack code cleanup.
 - Improved messaging around NLTK.
-## 101
+## v101
 Updated setuptools installation method.
 - Improved pipenv support.
-## 100
+## v100
 Preliminary pipenv support.
-## 99
+## v99
 Cleanup.
-## 98
+## v98
 Official NLTK support and other improvements.
 - Support for `nltk.txt` file for declaring corpora to be downloaded.
- Leading zeros for auto-set WEB_CONCURRENCY.
+- Leading zeros for auto-set `WEB_CONCURRENCY`.
-## 97
+## v97
 Improved egg-link functionality.
-## 96
+## v96
 Bugfix.
-## 95
+## v95
 Improved output support.
@@ -361,7 +494,7 @@ Fixed bug with editable pip installations.
 Updated default Python 2.7.13.
- Python 2.7.13 uses UCS-4 build, more compatibile with linux wheels.
+- Python 2.7.13 uses UCS-4 build, more compatible with linux wheels.
 - Updated setuptools to v32.1.0.
 ## v86
@@ -387,7 +520,7 @@ Support for Heroku CI.
 ## v82 (2016-08-22)
-Update to library detection mechnisms (pip-pop).
+Update to library detection mechanisms (pip-pop).
 - Updated setuptools to v25.5.0
@@ -461,7 +594,7 @@ Revert to v66.
 ## v68 (2015-10-12)
-Fixed .heroku/venv error with modern apps.
+Fixed `.heroku/venv` error with modern apps.
 ## v67 (2015-10-12)
@@ -486,7 +619,6 @@ Updated Pip and Setuptools.
 - Setuptools updated to v18.3.2
 - Pip updated to v7.1.2
 ## v62 (2015-08-07)
 Updated Pip and Setuptools.
@@ -4,3 +4,5 @@ gem "rspec"
 gem "heroku_hatchet"
 gem "rspec-retry"
 gem "rake"
 gem "parallel_split_test"
@@ -1,71 +1,60 @@
 GEM
  remote: https://rubygems.org/
  specs:
-    activesupport (5.2.1)
+    diff-lcs (1.4.4)
      concurrent-ruby (~> 1.0, >= 1.0.2)
      i18n (>= 0.7, < 2)
      minitest (~> 5.1)
      tzinfo (~> 1.1)
    concurrent-ruby (1.1.3)
    diff-lcs (1.3)
    erubis (2.7.0)
-    excon (0.62.0)
+    excon (0.78.0)
-    heroics (0.0.25)
+    heroics (0.1.1)
      erubis (~> 2.0)
      excon
      moneta
      multi_json (>= 1.9.2)
-    heroku_hatchet (4.0.6)
+    heroku_hatchet (7.3.3)
      excon (~> 0)
-      minitest-retry (~> 0.1.9)
+      platform-api (~> 3)
      platform-api (~> 2)
      repl_runner (~> 0.0.3)
      rrrretry (~> 1)
-      thor (~> 0)
+      thor (~> 1)
      threaded (~> 0)
    i18n (1.1.1)
      concurrent-ruby (~> 1.0)
    minitest (5.11.3)
    minitest-retry (0.1.9)
      minitest (>= 5.0)
    moneta (1.0.0)
-    multi_json (1.13.1)
+    multi_json (1.15.0)
-    platform-api (2.2.0)
+    parallel (1.19.2)
-      heroics (~> 0.0.25)
+    parallel_split_test (0.8.0)
      parallel (>= 0.5.13)
      rspec (>= 3.1.0)
    platform-api (3.0.0)
      heroics (~> 0.1.1)
      moneta (~> 1.0.0)
-    rake (12.3.1)
+      rate_throttle_client (~> 0.1.0)
-    repl_runner (0.0.3)
+    rake (13.0.1)
-      activesupport
+    rate_throttle_client (0.1.2)
    rrrretry (1.0.0)
-    rspec (3.8.0)
+    rspec (3.10.0)
-      rspec-core (~> 3.8.0)
+      rspec-core (~> 3.10.0)
-      rspec-expectations (~> 3.8.0)
+      rspec-expectations (~> 3.10.0)
-      rspec-mocks (~> 3.8.0)
+      rspec-mocks (~> 3.10.0)
-    rspec-core (3.8.0)
+    rspec-core (3.10.0)
-      rspec-support (~> 3.8.0)
+      rspec-support (~> 3.10.0)
-    rspec-expectations (3.8.1)
+    rspec-expectations (3.10.0)
      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.8.0)
+      rspec-support (~> 3.10.0)
-    rspec-mocks (3.8.0)
+    rspec-mocks (3.10.0)
      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.8.0)
+      rspec-support (~> 3.10.0)
-    rspec-retry (0.6.1)
+    rspec-retry (0.6.2)
      rspec-core (> 3.3)
-    rspec-support (3.8.0)
+    rspec-support (3.10.0)
-    thor (0.20.3)
+    thor (1.0.1)
    thread_safe (0.3.6)
    threaded (0.0.4)
    tzinfo (1.2.5)
      thread_safe (~> 0.1)
 PLATFORMS
  ruby
 DEPENDENCIES
  heroku_hatchet
  parallel_split_test
  rake
  rspec
  rspec-retry
 BUNDLED WITH
-   1.16.3
+   2.1.4
@@ -1,55 +1,61 @@
 # These targets are not files
-.PHONY: tests
+.PHONY: check test compile builder-image buildenv deploy-runtimes tools
-test: test-heroku-18 test-heroku-16 test-cedar-14
+STACK ?= heroku-18
 STACKS ?= heroku-16 heroku-18 heroku-20
 TEST_CMD ?= test/run-versions && test/run-features && test/run-deps
 FIXTURE ?= test/fixtures/requirements-standard
 ENV_FILE ?= builds/dockerenv.default
 BUILDER_IMAGE_PREFIX := heroku-python-build
 # Converts a stack name of `heroku-NN` to its build Docker image tag of `heroku/heroku:NN-build`.
 STACK_IMAGE_TAG := heroku/$(subst -,:,$(STACK))-build
 check:
 	@shellcheck -x bin/compile bin/detect bin/release bin/test-compile bin/utils bin/warnings bin/default_pythons
-	@shellcheck -x bin/steps/collectstatic bin/steps/eggpath-fix  bin/steps/eggpath-fix2 bin/steps/gdal bin/steps/geo-libs bin/steps/mercurial bin/steps/nltk bin/steps/pip-install bin/steps/pip-uninstall bin/steps/pipenv bin/steps/pipenv-python-version bin/steps/pylibmc bin/steps/python
+	@shellcheck -x bin/steps/collectstatic bin/steps/eggpath-fix  bin/steps/eggpath-fix2 bin/steps/nltk bin/steps/pip-install bin/steps/pipenv bin/steps/pipenv-python-version bin/steps/python
 	@shellcheck -x bin/steps/hooks/*
-test-cedar-14:
+test:
-	@echo "Running tests in docker (cedar-14)..."
+	@echo "Running tests using: STACK=$(STACK) TEST_CMD='$(TEST_CMD)'"
 	@docker run -v $(shell pwd):/buildpack:ro --rm -it -e "STACK=cedar-14" heroku/cedar:14 bash -c 'cp -r /buildpack /buildpack_test; cd /buildpack_test/; test/run-deps; test/run-features; test/run-versions;'
 	@echo ""
 test-heroku-16:
 	@echo "Running tests in docker (heroku-16)..."
 	@docker run -v $(shell pwd):/buildpack:ro --rm -it -e "STACK=heroku-16" heroku/heroku:16-build bash -c 'cp -r /buildpack /buildpack_test; cd /buildpack_test/; test/run-deps; test/run-features; test/run-versions;'
 	@echo ""
 test-heroku-18:
 	@echo "Running tests in docker (heroku-18)..."
 	@docker run -v $(shell pwd):/buildpack:ro --rm -it -e "STACK=heroku-18" heroku/heroku:18-build bash -c 'cp -r /buildpack /buildpack_test; cd /buildpack_test/; test/run-deps; test/run-features; test/run-versions;'
 	@echo ""
 buildenv-heroku-16:
 	@echo "Creating build environment (heroku-16)..."
 	@echo
-	@docker build --pull -f $(shell pwd)/builds/heroku-16.Dockerfile -t python-buildenv-heroku-16 .
+	@docker run --rm -it -v $(PWD):/buildpack:ro -e "STACK=$(STACK)" "$(STACK_IMAGE_TAG)" bash -c 'cp -r /buildpack /buildpack_test && cd /buildpack_test && $(TEST_CMD)'
 	@echo
 compile:
 	@echo "Running compile using: STACK=$(STACK) FIXTURE=$(FIXTURE)"
 	@echo
 	@docker run --rm -it -v $(PWD):/src:ro -e "STACK=$(STACK)" -w /buildpack "$(STACK_IMAGE_TAG)" \
 		bash -c 'cp -r /src/{bin,vendor} /buildpack && cp -r /src/$(FIXTURE) /build && mkdir /cache /env && bin/compile /build /cache /env'
 	@echo
 builder-image:
 	@echo "Generating binary builder image for $(STACK)..."
 	@echo
 	@docker build --pull -f builds/$(STACK).Dockerfile -t "$(BUILDER_IMAGE_PREFIX)-$(STACK)" .
 	@echo
 buildenv: builder-image
 	@echo "Starting build environment for $(STACK)..."
 	@echo
 	@echo "Usage..."
 	@echo
-	@echo "  $$ export AWS_ACCESS_KEY_ID=foo AWS_SECRET_ACCESS_KEY=bar  # Optional unless deploying"
+	@echo "  $$ bob build runtimes/python-X.Y.Z"
 	@echo "  $$ bob build runtimes/python-2.7.13"
 	@echo "  $$ bob deploy runtimes/python-2.7.13"
 	@echo
-	@docker run -it --rm python-buildenv-heroku-16
+	@docker run --rm -it --env-file="$(ENV_FILE)" -v $(PWD)/builds:/app/builds "$(BUILDER_IMAGE_PREFIX)-$(STACK)" bash
-buildenv-heroku-18:
+deploy-runtimes:
-	@echo "Creating build environment (heroku-18)..."
+ifndef RUNTIMES
 	$(error No runtimes specified! Use: "make deploy-runtimes RUNTIMES='python-X.Y.Z ...' [STACKS='heroku-18 ...'] [ENV_FILE=...]")
 endif
 	@echo "Using: RUNTIMES='$(RUNTIMES)' STACKS='$(STACKS)' ENV_FILE='$(ENV_FILE)'"
 	@echo
-	@docker build --pull -f $(shell pwd)/builds/heroku-18.Dockerfile -t python-buildenv-heroku-18 .
+	@set -eu; for stack in $(STACKS); do \
-	@echo
+		$(MAKE) builder-image STACK=$${stack}; \
-	@echo "Usage..."
+		for runtime in $(RUNTIMES); do \
-	@echo
+			echo "Generating/deploying $${runtime} for $${stack}..."; \
-	@echo "  $$ export AWS_ACCESS_KEY_ID=foo AWS_SECRET_ACCESS_KEY=bar  # Optional unless deploying"
+			echo; \
-	@echo "  $$ bob build runtimes/python-2.7.13"
+			docker run --rm -it --env-file="$(ENV_FILE)" "$(BUILDER_IMAGE_PREFIX)-$${stack}" bob deploy "runtimes/$${runtime}"; \
-	@echo "  $$ bob deploy runtimes/python-2.7.13"
+			echo; \
-	@echo
+		done; \
-	@docker run -it --rm python-buildenv-heroku-18
+	done
 tools:
 	git clone https://github.com/kennethreitz/pip-pop.git
 	mv pip-pop/bin/* vendor/pip-pop/
 	rm -fr pip-pop
@@ -1,27 +1,5 @@
 This buildpack includes some vendorized packages to ease installation.
 jq license
 ----------
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:
 The above copyright notice and this permission notice shall be included in all
 copies or substantial portions of the Software.
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 shunit2 license
 ---------------
@@ -85,53 +63,3 @@ The Free Software Foundation may publish revised and/or new versions of the GNU
 Each version is given a distinguishing version number. If the Library as you received it specifies that a certain numbered version of the GNU Lesser General Public License “or any later version” applies to it, you have the option of following the terms and conditions either of that published version or of any later version published by the Free Software Foundation. If the Library as you received it does not specify a version number of the GNU Lesser General Public License, you may choose any version of the GNU Lesser General Public License ever published by the Free Software Foundation.
 If the Library as you received it specifies that a proxy can decide whether future versions of the GNU Lesser General Public License shall apply, that proxy's public statement of acceptance of any version is permanent authorization for you to choose that version for the Library.
 get-pip.py license
 ------------------
 Copyright (c) 2008-2016 The pip developers (see AUTHORS.txt file)
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
 "Software"), to deal in the Software without restriction, including
 without limitation the rights to use, copy, modify, merge, publish,
 distribute, sublicense, and/or sell copies of the Software, and to
 permit persons to whom the Software is furnished to do so, subject to
 the following conditions:
 The above copyright notice and this permission notice shall be
 included in all copies or substantial portions of the Software.
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 pip-pop license
 ---------------
 The MIT License (MIT)
 Copyright (c) 2014 Kenneth Reitz.
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:
 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
@@ -1,9 +0,0 @@
 [[source]]
 url = "https://pypi.python.org/simple"
 verify_ssl = true
 name = "pypi"
 [dev-packages]
 [packages]
 "bob-builder" = "==0.0.13"
@@ -1,52 +0,0 @@
 {
    "_meta": {
        "hash": {
            "sha256": "36d17c46a8b1b844b3cae475f6f42d6c0a9e59b2a9685cbcdc0985656a7a129f"
        },
        "host-environment-markers": {
            "implementation_name": "cpython",
            "implementation_version": "3.6.3",
            "os_name": "posix",
            "platform_machine": "x86_64",
            "platform_python_implementation": "CPython",
            "platform_release": "16.7.0",
            "platform_system": "Darwin",
            "platform_version": "Darwin Kernel Version 16.7.0: Thu Jun 15 17:36:27 PDT 2017; root:xnu-3789.70.16~2/RELEASE_X86_64",
            "python_full_version": "3.6.3",
            "python_version": "3.6",
            "sys_platform": "darwin"
        },
        "pipfile-spec": 6,
        "requires": {},
        "sources": [
            {
                "name": "pypi",
                "url": "https://pypi.python.org/simple",
                "verify_ssl": true
            }
        ]
    },
    "default": {
        "bob-builder": {
            "hashes": [
                "sha256:b4de49a8e436fcaf82236ea43f78413b4a4c92100726e382ab57b6bdfb38fe64",
                "sha256:288e3e765c4890fe9a63ae52ac6b4a963c13fe508482c70ff701a5ae21b9a673"
            ],
            "version": "==0.0.13"
        },
        "boto": {
            "hashes": [
                "sha256:13be844158d1bd80a94c972c806ec8381b9ea72035aa06123c5db6bc6a6f3ead",
                "sha256:deb8925b734b109679e3de65856018996338758f4b916ff4fe7bb62b6d7000d1"
            ],
            "version": "==2.48.0"
        },
        "docopt": {
            "hashes": [
                "sha256:49b3a825280bd66b3aa83585ef59c4a8c82f2c8a522dbe754a8bc8d08c85c491"
            ],
            "version": "==0.6.2"
        }
    },
    "develop": {}
 }
@@ -2,7 +2,7 @@
 # Heroku Buildpack: Python
-[![Build Status](https://travis-ci.org/heroku/heroku-buildpack-python.svg?branch=master)](https://travis-ci.org/heroku/heroku-buildpack-python)
+[![Build Status](https://travis-ci.com/heroku/heroku-buildpack-python.svg?branch=main)](https://travis-ci.com/heroku/heroku-buildpack-python)
 This is the official [Heroku buildpack](https://devcenter.heroku.com/articles/buildpacks) for Python apps.
@@ -16,7 +16,7 @@ See it in Action
 $ ls
 my-application		requirements.txt	runtime.txt
-$ git push heroku master
+$ git push heroku main
 Counting objects: 4, done.
 Delta compression using up to 8 threads.
 Compressing objects: 100% (2/2), done.
@@ -26,7 +26,7 @@ remote: Compressing source files... done.
 remote: Building source:
 remote:
 remote: -----> Python app detected
-remote: -----> Installing python-3.7.4
+remote: -----> Installing python
 remote: -----> Installing pip
 remote: -----> Installing SQLite3
 remote: -----> Installing requirements with pip
@@ -44,9 +44,10 @@ A `requirements.txt` must be present at the root of your application's repositor
 To specify your python version, you also need a `runtime.txt` file - unless you are using the default Python runtime version.
-Current default Python Runtime: Python 3.6.9
+Current default Python Runtime: Python 3.6.12
-Alternatively, you can provide a `setup.py` file, or a `Pipfile`. Using `Pipenv` will generate `runtime.txt` based on `python-version` at build time.
+Alternatively, you can provide a `setup.py` file, or a `Pipfile`.
 Using `pipenv` will generate `runtime.txt` at build time if one of the field `python_version` or `python_full_version` is specified in the `requires` section of your `Pipfile`.
 Specify a Buildpack Version
 ---------------------------
@@ -61,26 +62,33 @@ Specify a Python Runtime
 Supported runtime options include:
- `python-3.7.4`
+- `python-3.9.0`
- `python-3.6.9`
+- `python-3.8.7`
- `python-2.7.17`
+- `python-3.7.9`
 - `python-3.6.12`
 - `python-2.7.18`
 ## Tests
 The buildpack tests use [Docker](https://www.docker.com/) to simulate
 Heroku's [stack images.](https://devcenter.heroku.com/articles/stack)
-To run the test suite:
+To run the test suite against the default stack:
 ```
 make test
 ```
-Or to test in a particular stack:
+Or to test against a particular stack:
 ```
-make test-heroku-18
+make test STACK=heroku-16
-make test-heroku-16
+```
 To run only a subset of the tests:
 ```
 make test TEST_CMD=tests/versions
 ```
 The tests are run via the vendored
@@ -15,7 +15,7 @@
 # Fail fast and fail hard.
 set -eo pipefail
-# Boostrap the Buildpack Standard Library.
+# Used by buildpack-stdlib's metrics features.
 export BPLOG_PREFIX="buildpack.python"
 export BUILDPACK_LOG_FILE=${BUILDPACK_LOG_FILE:-/dev/null}
@@ -35,23 +35,19 @@ ENV_DIR=$3
 # Export Path variables, for use in sub-scripts.
 export BUILD_DIR CACHE_DIR ENV_DIR
-# Set the Buildpack's internet target for downloading Python distributions.
+# Set the base URL for downloading buildpack assets like Python runtimes.
-# The user can provide BUILDPACK_VENDOR_URL to specify a custom target.
+# The user can provide BUILDPACK_S3_BASE_URL to specify a custom target.
 # Note: this is designed for non-Heroku use, as it does not use the user-provided
 # environment variable mechanism (the ENV_DIR).
-VENDOR_URL="https://lang-python.s3.amazonaws.com/$STACK"
+S3_BASE_URL="${BUILDPACK_S3_BASE_URL:-"https://heroku-buildpack-python.s3.amazonaws.com"}"
-if [[ -n ${BUILDPACK_VENDOR_URL:-} ]]; then
+# This has to be exported since it's used by the geo-libs step which is run in a subshell.
    VENDOR_URL="$BUILDPACK_VENDOR_URL"
 elif [[ -n ${USE_STAGING_BINARIES} ]]; then
    VENDOR_URL="$USE_STAGING_BINARIES/$STACK"
 fi
 export VENDOR_URL
 # Default Python Versions
 # shellcheck source=bin/default_pythons
 source "$BIN_DIR/default_pythons"
 # Supported Python Branches
 PY39="python-3.9"
 PY38="python-3.8"
 PY37="python-3.7"
 PY36="python-3.6"
@@ -62,57 +58,28 @@ PYPY27="pypy2.7"
 PYPY36="pypy3.6"
 # Which stack is used (for binary downloading), if none is provided (e.g. outside of Heroku)?
-DEFAULT_PYTHON_STACK="cedar-14"
+# TODO: Remove this and require that STACK be set explicitly.
-# If pip doesn't match this version (the version we install), run the installer.
+DEFAULT_PYTHON_STACK="heroku-18"
 PIP_UPDATE="20.0.2"
 for file in "$BUILD_DIR/runtime.txt" "$CACHE_DIR/.heroku/python-version" ; do
    [ -f "$file" ] || continue
    version=$(tr -d '[:space:]' < "$file")
    case "$version" in "$PY34"*)
        # Python 3.4 support was dropped in pip >= 19.2.
        PIP_UPDATE="19.1.1"
        break
        ;;
    esac
 done
 if [[ -f "$BUILD_DIR/Pipfile" ]]; then
    # Do not force pipenv users to re-install pipenv locally.
    PIP_UPDATE="9.0.2"
 fi
 export DEFAULT_PYTHON_STACK PIP_UPDATE
 export PY37 PY36 PY35 PY27 PY34
 # Common Problem Warnings:
 # This section creates a temporary file in which to stick the output of `pip install`.
 # The `warnings` subscript then greps through this for common problems and guides
 # the user towards resolution of known issues.
 WARNINGS_LOG=$(mktemp)
-export WARNINGS_LOG
+RECOMMENDED_PYTHON_VERSION=$DEFAULT_PYTHON_VERSION
 export RECOMMENDED_PYTHON_VERSION=$DEFAULT_PYTHON_VERSION
-# The buildpack ships with a few executable tools (e.g. pip-grep, etc).
+# The buildpack ships with a few executable tools.
 # This installs them into the path, so we can execute them directly.
-export PATH=$PATH:$ROOT_DIR/vendor/:$ROOT_DIR/vendor/pip-pop
+export PATH=$PATH:$ROOT_DIR/vendor/
 # Set environment variables if they weren't set by the platform.
 # Note: this is legacy, for a deprecated build system known as Anvil.
 # This can likely be removed, with caution.
 [ ! "$SLUG_ID" ] && SLUG_ID="defaultslug"
 [ ! "$REQUEST_ID" ] && REQUEST_ID=$SLUG_ID
 [ ! "$STACK" ] && STACK=$DEFAULT_PYTHON_STACK
 # Sanitize externally-provided environment variables:
 # The following environment variables are either problematic or simply unneccessary
 # for the buildpack to have knowledge of, so we unset them, to keep the environment
 # as clean and pristine as possible.
-unset GIT_DIR PYTHONHOME PYTHONPATH
+unset PYTHONHOME PYTHONPATH
 unset RECEIVE_DATA RUN_KEY BUILD_INFO DEPLOY LOG_TOKEN
 unset CYTOKINE_LOG_FILE GEM_PATH
 # Import the utils script, which contains helper functions used throughout the buildpack.
 # shellcheck source=bin/utils
@@ -123,6 +90,33 @@ source "$BIN_DIR/utils"
 # shellcheck source=bin/warnings
 source "$BIN_DIR/warnings"
 if [[ "${STACK}" == "cedar-14" ]]; then
  mcount "failure.unsupported.cedar-14"
  puts-warn "The Cedar-14 stack is no longer supported by the latest release of this buildpack."
  puts-warn
  puts-warn "Please switch to the Cedar-14 support branch by using this buildpack URL:"
  puts-warn "https://github.com/heroku/heroku-buildpack-python#cedar-14"
  puts-warn
  puts-warn "For instructions on how to change the buildpacks used by an app, see:"
  puts-warn "https://devcenter.heroku.com/articles/buildpacks#setting-a-buildpack-on-an-application"
  exit 1
 fi
 if [[ -f "${ENV_DIR}/BUILD_WITH_GEO_LIBRARIES" ]]; then
  mcount "failure.unsupported.BUILD_WITH_GEO_LIBRARIES"
  puts-warn "The Python buildpack's legacy BUILD_WITH_GEO_LIBRARIES functonality is"
  puts-warn "no longer supported:"
  puts-warn "https://devcenter.heroku.com/changelog-items/1947"
  puts-warn
  puts-warn "To continue to use GDAL, GEOS or PROJ support, see the migration guide:"
  puts-warn "https://help.heroku.com/D5INLB1A/python-s-build_with_geo_libraries-legacy-feature-is-no-longer-supported"
  puts-warn
  puts-warn "Or if you no longer need those libraries, this message can be hidden by"
  puts-warn "unsetting the BUILD_WITH_GEO_LIBRARIES environment variable, using:"
  puts-warn "heroku config:unset BUILD_WITH_GEO_LIBRARIES"
  exit 1
 fi
 # Make the directory in which we will create symlinks from the temporary build directory
 # to `/app`.
 # Symlinks are required, since Python is not a portable installation.
@@ -151,14 +145,19 @@ export PYTHONUNBUFFERED=1
 # Set the locale to a well-known and expected standard.
 export LANG=en_US.UTF-8
 # `~/.heroku/vendor` is an place where the buildpack may stick pre-build binaries for known
-# C dependencies (e.g. libmemcached on cedar-14). This section configures Python (GCC, more specifically)
+# C dependencies. This section configures Python (GCC, more specifically)
 # and pip to automatically include these paths when building binaries.
 # TODO: Stop adding .heroku/vendor here now that the buildpack no longer vendors anything.
 export C_INCLUDE_PATH=/app/.heroku/vendor/include:/app/.heroku/python/include:$C_INCLUDE_PATH
 export CPLUS_INCLUDE_PATH=/app/.heroku/vendor/include:/app/.heroku/python/include:$CPLUS_INCLUDE_PATH
 export LIBRARY_PATH=/app/.heroku/vendor/lib:/app/.heroku/python/lib:$LIBRARY_PATH
 export LD_LIBRARY_PATH=/app/.heroku/vendor/lib:/app/.heroku/python/lib:$LD_LIBRARY_PATH
 export PKG_CONFIG_PATH=/app/.heroku/vendor/lib/pkg-config:/app/.heroku/python/lib/pkg-config:$PKG_CONFIG_PATH
 # Global pip options (https://pip.pypa.io/en/stable/user_guide/#environment-variables).
 # Disable pip's warnings about EOL Python since we show our own.
 export PIP_NO_PYTHON_VERSION_WARNING=1
 # The Application Code
 # --------------------
@@ -175,7 +174,7 @@ cd "$BUILD_DIR"
 # - Once the build is complete, `~/.heroku/{known-paths}` is copied back into the cache.
 # Create the cache directory, if it doesn't exist.
-mkdir -p "$CACHE_DIR"
+mkdir -p "$CACHE_DIR/.heroku"
 # Restore old artifacts from the cache.
 mkdir -p .heroku
@@ -188,8 +187,6 @@ cp -R "$CACHE_DIR/.heroku/python-stack" .heroku/ &> /dev/null || true
 cp -R "$CACHE_DIR/.heroku/python-version" .heroku/ &> /dev/null || true
 # A plain text file which contains the current sqlite3 version being used (used for cache busting).
 cp -R "$CACHE_DIR/.heroku/python-sqlite3-version" .heroku/ &> /dev/null || true
 # Any pre-compiled binaries, provided by the buildpack.
 cp -R "$CACHE_DIR/.heroku/vendor" .heroku/ &> /dev/null || true
 # "editable" installations of code repositories, via pip or pipenv.
 if [[ -d "$CACHE_DIR/.heroku/src" ]]; then
  cp -R "$CACHE_DIR/.heroku/src" .heroku/ &> /dev/null || true
@@ -207,7 +204,7 @@ source "$BIN_DIR/steps/hooks/pre_compile"
 # continue to use that version of Python in perpituity (warnings will be raised if
 # they are out–of–date).
 if [ -f "$CACHE_DIR/.heroku/python-version" ]; then
-  DEFAULT_PYTHON_VERSION=$(cat "$CACHE_DIR/.heroku/python-version")
+  CACHED_PYTHON_VERSION=$(cat "$CACHE_DIR/.heroku/python-version")
 fi
 # We didn't always record the stack version. This code is in place because of that.
@@ -217,8 +214,6 @@ else
  CACHED_PYTHON_STACK=$STACK
 fi
 export CACHED_PYTHON_STACK
 # Pipenv Python version support.
 # Detect the version of Python requested from a Pipfile (e.g. python_version or python_full_version).
 # Convert it to a runtime.txt file.
@@ -226,9 +221,14 @@ export CACHED_PYTHON_STACK
 # shellcheck source=bin/steps/pipenv-python-version
 source "$BIN_DIR/steps/pipenv-python-version"
-# If no runtime was provided by the user, assume the default Python runtime version.
+if [[ -f runtime.txt ]]; then
-if [ ! -f runtime.txt ]; then
+  mcount "version.reason.python.specified"
-  echo "$DEFAULT_PYTHON_VERSION" > runtime.txt
+elif [[ -n "${CACHED_PYTHON_VERSION:-}" ]]; then
  mcount "version.reason.python.cached"
  echo "${CACHED_PYTHON_VERSION}" > runtime.txt
 else
  mcount "version.reason.python.default"
  echo "${DEFAULT_PYTHON_VERSION}" > runtime.txt
 fi
 # Create the directory for .profile.d, if it doesn't exist.
@@ -259,17 +259,8 @@ mtime "python.install.time" "${start}"
 # shellcheck source=bin/steps/pipenv
 source "$BIN_DIR/steps/pipenv"
 # Uninstall removed dependencies with Pip.
 # The buildpack will automatically remove any declared dependencies (in requirements.txt)
 # that were explicitly removed. This machinery is a bit complex, but it is not complicated.
 (( start=$(nowms) ))
 # shellcheck source=bin/steps/pip-uninstall
 source "$BIN_DIR/steps/pip-uninstall"
 mtime "pip.uninstall.time" "${start}"
 # If no requirements.txt file given, assume `setup.py develop` is intended.
 # This allows for people to ship a setup.py application to Heroku
 # (which is rare, but I vouch that it should work!)
 if [ ! -f requirements.txt ] && [ ! -f Pipfile ]; then
  echo "-e ." > requirements.txt
@@ -281,27 +272,6 @@ fi
 # shellcheck source=bin/steps/eggpath-fix
 source "$BIN_DIR/steps/eggpath-fix"
 # Mercurial support.
 # If a customer appears to be using mercurial for dependency resolution, we install it first.
 # Note: this only applies to pip, not pipenv. This can likely be removed, over time. Measure it first.
 # shellcheck source=bin/steps/mercurial
 source "$BIN_DIR/steps/mercurial"
 # Pylibmc support.
 # On cedar-14, libmemcached was not available. The buildpack provides its own version, instead.
 # shellcheck source=bin/steps/pylibmc
 source "$BIN_DIR/steps/pylibmc"
 # Support for Geo libraries. This is deprecated functionality, only functional on cedar-14.
 # It is undocumented.
 # shellcheck source=bin/steps/geo-libs
 sub_env "$BIN_DIR/steps/geo-libs"
 # GDAL support.
 # This is part of the Geo support.
 # shellcheck source=bin/steps/gdal
 source "$BIN_DIR/steps/gdal"
 # SQLite3 support.
 # This sets up and installs sqlite3 dev headers and the sqlite3 binary but not the
 # libsqlite3-0 library since that exists on the stack image.
@@ -333,7 +303,7 @@ mtime "nltk.download.time" "${start}"
 # and copying it into the proper place (the logical place to do this was early, but it must be done here).
 # In CI, $BUILD_DIR is /app.
 if [[ ! "$BUILD_DIR" == "/app" ]]; then
-  rm -fr "$BUILD_DIR/.heroku/src"
+  rm -rf "$BUILD_DIR/.heroku/src"
  deep-cp /app/.heroku/src "$BUILD_DIR/.heroku/src"
 fi
@@ -399,7 +369,6 @@ mkdir -p "$CACHE_DIR/.heroku"
 cp -R .heroku/python "$CACHE_DIR/.heroku/"
 cp -R .heroku/python-version "$CACHE_DIR/.heroku/"
 cp -R .heroku/python-stack "$CACHE_DIR/.heroku/" &> /dev/null || true
 cp -R .heroku/vendor "$CACHE_DIR/.heroku/" &> /dev/null || true
 if [[ -d .heroku/src ]]; then
  cp -R .heroku/src "$CACHE_DIR/.heroku/" &> /dev/null || true
 fi
@@ -1,21 +1,17 @@
 #!/usr/bin/env bash
-DEFAULT_PYTHON_VERSION="python-3.6.10"
+# Disable unused env var warning, since shellcheck doesn't take into account
-LATEST_38="python-3.8.1"
+# that this file is sourced. We don't want to use export since it exposes
-LATEST_37="python-3.7.6"
+# the env vars to subprocesses.
-LATEST_36="python-3.6.10"
+# shellcheck disable=2034
 LATEST_35="python-3.5.7"
 LATEST_34="python-3.4.10"
 LATEST_27="python-2.7.17"
 PYPY_36="pypy3.6-7.2.0"
 PYPY_27="pypy2.7-7.2.0"
-export DEFAULT_PYTHON_VERSION \
+DEFAULT_PYTHON_VERSION="python-3.6.12"
-    LATEST_38 \
+LATEST_39="python-3.9.0"
-    LATEST_37 \
+LATEST_38="python-3.8.7"
-    LATEST_36 \
+LATEST_37="python-3.7.9"
-    LATEST_35 \
+LATEST_36="python-3.6.12"
-    LATEST_34 \
+LATEST_35="python-3.5.10"
-    LATEST_27 \
+LATEST_34="python-3.4.10"
-    PYPY_36 \
+LATEST_27="python-2.7.18"
-    PYPY_27
+LATEST_PYPY_36="pypy3.6-7.3.2"
 LATEST_PYPY_27="pypy2.7-7.3.2"
@@ -0,0 +1,21 @@
 # Python Buildpack Install Steps
 TODO: Add context on Python install steps, such as why symlinking vs copying
 ## Installing Python packages using Pip
 ### Convention: Use `python` process to invoke Pip
 We don't use this convention (yet) but this is an upcoming change being considered.
 This is a bigger concern on Windows than it is in Linux environments, but an
 emerging convention in the Python community is to invoke pip using:
 ```
 python3 -m pip [options]
 ```
 Invoking pip this way ensures correct location - python knows where these
 packages are stored because it put them there (defaults to Python's pathing info).
 All normal command line options are available using this method.
@@ -20,8 +20,8 @@ MANAGE_FILE=${MANAGE_FILE:-fakepath}
 # Legacy file-based support for $DISABLE_COLLECTSTATIC
 [ -f .heroku/collectstatic_disabled ] && DISABLE_COLLECTSTATIC=1
-# Ensure that Django is explicitly specified in requirements.txt
+# Ensure that Django is actually installed.
-sp-grep -s django && DJANGO_INSTALLED=1
+is_module_available 'django' && DJANGO_INSTALLED=1
 if [ ! "$DISABLE_COLLECTSTATIC" ] && [ -f "$MANAGE_FILE" ] && [ "$DJANGO_INSTALLED" ]; then
@@ -1,34 +0,0 @@
 #!/usr/bin/env bash
 # This script serves as the GDAL build step of the
 # [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
 # compiler.
 #
 # A [buildpack](https://devcenter.heroku.com/articles/buildpacks) is an
 # adapter between a Python application and Heroku's runtime.
 #
 # This script is invoked by [`bin/compile`](/).
 # The location of the pre-compiled cryptography binary.
 VENDORED_GDAL="${VENDOR_URL}/libraries/vendor/gdal.tar.gz"
 PKG_CONFIG_PATH="/app/.heroku/vendor/lib/pkgconfig:$PKG_CONFIG_PATH"
 # Syntax sugar.
 # shellcheck source=bin/utils
 source "$BIN_DIR/utils"
 # If GDAL exists within requirements, use vendored gdal.
 if (pip-grep -s requirements.txt GDAL gdal pygdal &> /dev/null) then
  if [ ! -f ".heroku/vendor/bin/gdalserver" ]; then
    echo "-----> Noticed GDAL. Bootstrapping gdal."
    mkdir -p .heroku/vendor
    # Download and extract cryptography into target vendor directory.
    curl "$VENDORED_GDAL" -s | tar zxv -C .heroku/vendor &> /dev/null
    mcount "steps.vendor.gdal"
  fi
  GDAL=$(pwd)/vendor
  export GDAL
 fi
@@ -1,52 +0,0 @@
 #!/usr/bin/env bash
 # This script serves as the GDAL build step of the
 # [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
 # compiler.
 #
 # A [buildpack](https://devcenter.heroku.com/articles/buildpacks) is an
 # adapter between a Python application and Heroku's runtime.
 #
 # This script is invoked by [`bin/compile`](/).
 # The location of the pre-compiled cryptography binary.
 VENDORED_GDAL="${VENDOR_URL}/libraries/vendor/gdal.tar.gz"
 VENDORED_GEOS="${VENDOR_URL}/libraries/vendor/geos.tar.gz"
 VENDORED_PROJ="${VENDOR_URL}/libraries/vendor/proj.tar.gz"
 PKG_CONFIG_PATH="/app/.heroku/vendor/lib/pkgconfig:$PKG_CONFIG_PATH"
 # Syntax sugar.
 # shellcheck source=bin/utils
 source "$BIN_DIR/utils"
 # If GDAL exists within requirements, use vendored gdal.
 if [[ "$BUILD_WITH_GEO_LIBRARIES" ]]; then
  mcount "buildvar.BUILD_WITH_GEO_LIBRARIES"
  if [ ! -f ".heroku/vendor/bin/proj" ]; then
    echo "-----> Bootstrapping gdal, geos, proj."
    mkdir -p .heroku/vendor
    # Download and extract cryptography into target vendor directory.
    curl "$VENDORED_GDAL" -s | tar zxv -C .heroku/vendor &> /dev/null
    curl "$VENDORED_GEOS" -s | tar zxv -C .heroku/vendor &> /dev/null
    curl "$VENDORED_PROJ" -s | tar zxv -C .heroku/vendor &> /dev/null
    mcount "steps.vendor.geo_libs"
    # Copy libjasper from build image to slug.
    if [[ "$STACK" == "heroku-16" ]]; then
      cp /usr/lib/x86_64-linux-gnu/libjasper.so* ".heroku/vendor/lib/."
      mcount "steps.vendor.libjasper"
    fi
  fi
  GDAL=$(pwd)/vendor
  export GDAL
  # set path for post_compile hooks
  export GDAL_LIBRARY_PATH="$BUILD_DIR/.heroku/vendor/lib/libgdal.so"
  export GEOS_LIBRARY_PATH="$BUILD_DIR/.heroku/vendor/lib/libgeos_c.so"
  # set path for runtime environmeht
  set_env GDAL_LIBRARY_PATH "/app/.heroku/vendor/lib/libgdal.so"
  set_env GEOS_LIBRARY_PATH "/app/.heroku/vendor/lib/libgeos_c.so"
 fi
@@ -1,9 +0,0 @@
 #!/usr/bin/env bash
 # Install Mercurial if it appears to be required.
 if [[ -f "requirements.txt" ]]; then
 	if (grep -Fiq "hg+" requirements.txt) then
 		/app/.heroku/python/bin/pip install  mercurial | cleanup | indent
 		mcount "steps.mercurial"
 	fi
 fi
@@ -14,7 +14,7 @@
 source "$BIN_DIR/utils"
 # Check that nltk was installed by pip, otherwise obviously not needed
-if sp-grep -s nltk; then
+if is_module_available 'nltk'; then
    puts-step "Downloading NLTK corpora…"
    nltk_packages_definition="$BUILD_DIR/nltk.txt"
@@ -38,9 +38,16 @@ if [ ! "$SKIP_PIP_INSTALL" ]; then
        mcount "failure.none-version"
    fi
    if grep -qi '^django==1.*' requirements.txt; then
        puts-warn "Your Django version is nearing the end of its community support."
        puts-warn "Upgrade to continue to receive security updates and for the best experience with Django."
        puts-warn "For more information, check out https://www.djangoproject.com/download/#supported-versions"
    fi
    if [ ! -f "$BUILD_DIR/.heroku/python/bin/pip" ]; then
        exit 1
    fi
    /app/.heroku/python/bin/pip install -r "$BUILD_DIR/requirements.txt" --exists-action=w --src=/app/.heroku/src --disable-pip-version-check --no-cache-dir 2>&1 | tee "$WARNINGS_LOG" | cleanup | indent
    PIP_STATUS="${PIPESTATUS[0]}"
    set -e
@@ -52,12 +59,9 @@ if [ ! "$SKIP_PIP_INSTALL" ]; then
        exit 1
    fi
    # Smart Requirements handling
    cp requirements.txt .heroku/python/requirements-declared.txt
    /app/.heroku/python/bin/pip freeze --disable-pip-version-check > .heroku/python/requirements-installed.txt
    echo
    # Install test dependencies, for CI.
    if [ "$INSTALL_TEST" ]; then
        if [[ -f "$1/requirements-test.txt" ]]; then
@@ -1,28 +0,0 @@
 #!/usr/bin/env bash
 set +e
 # Install dependencies with Pip.
 # shellcheck source=bin/utils
 source "$BIN_DIR/utils"
 if [ ! "$SKIP_PIP_INSTALL" ]; then
  if [[ -f .heroku/python/requirements-declared.txt ]]; then
    cp .heroku/python/requirements-declared.txt requirements-declared.txt
    if ! pip-diff --stale requirements-declared.txt requirements.txt --exclude setuptools pip wheel > .heroku/python/requirements-stale.txt; then
      mcount "failure.bad-requirements"
    fi
    rm -fr requirements-declared.txt
    if [[ -s .heroku/python/requirements-stale.txt ]]; then
      puts-step "Uninstalling stale dependencies"
      /app/.heroku/python/bin/pip uninstall -r .heroku/python/requirements-stale.txt -y --exists-action=w --disable-pip-version-check | cleanup | indent
    fi
  fi
 fi
 set -e
@@ -9,10 +9,7 @@ set -e
 if [[ -f Pipfile.lock ]]; then
    if [[ -f .heroku/python/Pipfile.lock.sha256 ]]; then
        if [[ $(openssl dgst -sha256 Pipfile.lock) == $(cat .heroku/python/Pipfile.lock.sha256) ]]; then
-            # Measure that we're using Pipenv.
+            # Don't skip installation if there are git deps.
            mcount "tool.pipenv"
            # Don't skip installation of there are git deps.
            if ! grep -q 'git' Pipfile.lock; then
                echo "Skipping installation, as Pipfile.lock hasn't changed since last deploy." | indent
@@ -72,7 +69,6 @@ if [ ! "$SKIP_PIPENV_INSTALL" ]; then
        else
            pipenv-to-pip Pipfile.lock > requirements.txt
            "$BIN_DIR/steps/pip-uninstall"
            cp requirements.txt .heroku/python/requirements-declared.txt
            openssl dgst -sha256 Pipfile.lock > .heroku/python/Pipfile.lock.sha256
@@ -27,6 +27,12 @@ if [[ -f $BUILD_DIR/Pipfile ]]; then
                if [ "$PYTHON" = 3.7 ]; then
                    echo "$LATEST_37" > "$BUILD_DIR/runtime.txt"
                fi
                if [ "$PYTHON" = 3.8 ]; then
                    echo "$LATEST_38" > "$BUILD_DIR/runtime.txt"
                fi
                if [ "$PYTHON" = 3.9 ]; then
                    echo "$LATEST_39" > "$BUILD_DIR/runtime.txt"
                fi
            fi
@@ -1,37 +0,0 @@
 #!/usr/bin/env bash
 # This script serves as the Pylibmc build step of the
 # [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
 # compiler.
 #
 # A [buildpack](https://devcenter.heroku.com/articles/buildpacks) is an
 # adapter between a Python application and Heroku's runtime.
 #
 # This script is invoked by [`bin/compile`](/).
 if [[ "$STACK" != "cedar-14" ]]; then
    # libmemcached is pre-installed in the stack image so there is no need to vendor it.
    return 0
 fi
 # The location of the pre-compiled libmemcached binary.
 VENDORED_MEMCACHED="${VENDOR_URL}/libraries/vendor/libmemcache.tar.gz"
 # Syntax sugar.
 # shellcheck source=bin/utils
 source "$BIN_DIR/utils"
 # If pylibmc exists within requirements, use vendored libmemcached.
 if (pip-grep -s requirements.txt pylibmc &> /dev/null) then
  if [ ! -d ".heroku/vendor/lib/sasl2" ]; then
    echo "-----> Noticed pylibmc. Bootstrapping libmemcached."
    mkdir -p .heroku/vendor
    # Download and extract libmemcached into target vendor directory.
    curl "$VENDORED_MEMCACHED" -s | tar zxv -C .heroku/vendor &> /dev/null
    mcount "steps.vendor.pylibmc"
  fi
  LIBMEMCACHED=$(pwd)/vendor
  export LIBMEMCACHED
 fi
@@ -5,9 +5,10 @@ runtime-fixer runtime.txt
 PYTHON_VERSION=$(cat runtime.txt)
 # The location of the pre-compiled python binary.
-VENDORED_PYTHON="${VENDOR_URL}/runtimes/$PYTHON_VERSION.tar.gz"
+VENDORED_PYTHON="${S3_BASE_URL}/${STACK}/runtimes/${PYTHON_VERSION}.tar.gz"
 SECURITY_UPDATE="Python has released a security update! Please consider upgrading to"
 SECURITY_UPDATE_PYPY="The PyPy project has released a security update! Please consider upgrading to"
 ONLY_SUPPORTED_2_VERSION="Only the latest version of Python 2 is supported on the platform. Please consider upgrading to"
@@ -15,6 +16,12 @@ PYTHON_2_EOL_UPDATE="Python 2 has reached it's community EOL. Upgrade your Pytho
 # check if runtime exists
 if curl --output /dev/null --silent --head --fail "$VENDORED_PYTHON"; then
  if [[ "$PYTHON_VERSION" == $PY39* ]]; then
    if [ "$PYTHON_VERSION" != "$LATEST_39" ]; then
      puts-warn "$SECURITY_UPDATE" "$LATEST_39"
      echo "       Learn More: https://devcenter.heroku.com/articles/python-runtimes"
    fi
  fi
  if [[ "$PYTHON_VERSION" == $PY38* ]]; then
    # do things to alert the user of security release available
    if [ "$PYTHON_VERSION" != "$LATEST_38" ]; then
@@ -51,11 +58,9 @@ if curl --output /dev/null --silent --head --fail "$VENDORED_PYTHON"; then
    fi
  fi
  if [[ "$PYTHON_VERSION" == $PY27* ]]; then
    puts-warn "$PYTHON_2_EOL_UPDATE"
    echo "       Learn More: https://devcenter.heroku.com/articles/python-2-7-eol-faq"
    # security update note
    if [[ "$(date "+%Y")" -gt "2019" ]]; then
      puts-warn "$PYTHON_2_EOL_UPDATE"
      echo "       Learn More: https://devcenter.heroku.com/articles/python-2-7-eol-faq"
    fi
    if [ "$PYTHON_VERSION" != "$LATEST_27" ]; then
      puts-warn "$ONLY_SUPPORTED_2_VERSION" "$LATEST_27"
      echo "       Learn More: https://devcenter.heroku.com/articles/python-runtimes"
@@ -63,15 +68,15 @@ if curl --output /dev/null --silent --head --fail "$VENDORED_PYTHON"; then
  fi
  if [[ "$PYTHON_VERSION" == $PYPY27* ]]; then
    # security update note
-    if [ "$PYTHON_VERSION" != "$PYPY_27" ]; then
+    if [ "$PYTHON_VERSION" != "$LATEST_PYPY_27" ]; then
-      puts-warn "Could not find that Pypy version. Did you mean" "${PYPY_27}?"
+      puts-warn "$SECURITY_UPDATE_PYPY" "$LATEST_PYPY_27"
      echo "       Learn More: https://devcenter.heroku.com/articles/python-runtimes"
    fi
  fi
  if [[ "$PYTHON_VERSION" == $PYPY36* ]]; then
    # security update note
-    if [ "$PYTHON_VERSION" != "$PYPY_36" ]; then
+    if [ "$PYTHON_VERSION" != "$LATEST_PYPY_36" ]; then
-      puts-warn "Could not find that Pypy version. Did you mean" "${PYPY_36}?"
+      puts-warn "$SECURITY_UPDATE_PYPY" "$LATEST_PYPY_36"
      echo "       Learn More: https://devcenter.heroku.com/articles/python-runtimes"
    fi
  fi
@@ -81,28 +86,40 @@ else
  exit 1
 fi
 mcount "version.python.${PYTHON_VERSION}"
 if [[ "$STACK" != "$CACHED_PYTHON_STACK" ]]; then
    puts-step "Stack has changed from $CACHED_PYTHON_STACK to $STACK, clearing cache"
-    rm -fr .heroku/python-stack .heroku/python-version .heroku/python .heroku/vendor .heroku/python .heroku/python-sqlite3-version
+    rm -rf .heroku/python-stack .heroku/python-version .heroku/python .heroku/vendor .heroku/python .heroku/python-sqlite3-version
 fi
 # need to clear the cache for first time installing SQLite3,
 # since the version is changing and could lead to runtime errors
 # with compiled extensions.
 if [ -d .heroku/python ] && [ ! -f .heroku/python-sqlite3-version ] && python_sqlite3_check "$PYTHON_VERSION"; then
  puts-step "Need to update SQLite3, clearing cache"
  rm -fr .heroku/python-stack .heroku/python-version .heroku/python .heroku/vendor
 fi
 if [ -f .heroku/python-version ]; then
  if [ ! "$(cat .heroku/python-version)" = "$PYTHON_VERSION" ]; then
      puts-step "Found $(cat .heroku/python-version), removing"
-      rm -fr .heroku/python
+      rm -rf .heroku/python
  else
    SKIP_INSTALL=1
  fi
 fi
 # Check if we should reinstall python dependencies
 if [[ ! -f "$CACHE_DIR/.heroku/requirements.txt" ]]; then
  # IF there's no cached dependencies, update cached version of requirements.txt
  # This should only run for new apps and first deploys after this update
  cp -R "$BUILD_DIR/requirements.txt" "$CACHE_DIR/.heroku/requirements.txt"
 else
  # IF there IS a cached directory, check for differences with the new one
  if ! diff "$BUILD_DIR/requirements.txt" "$CACHE_DIR/.heroku/requirements.txt" &> /dev/null; then
    puts-step "Requirements file has been changed, clearing cached dependencies"
    # if there are any differences, clear the Python cache
    # Installing Python over again does not take noticably more time
    cp -R "$BUILD_DIR/requirements.txt" "$CACHE_DIR/.heroku/requirements.txt"
    rm -rf .heroku/python
    unset SKIP_INSTALL
  else
    puts-step "No change in requirements detected, installing from cache"
  fi
 fi
 if [ ! "$SKIP_INSTALL" ]; then
    puts-step "Installing $PYTHON_VERSION"
@@ -110,8 +127,6 @@ if [ ! "$SKIP_INSTALL" ]; then
    # Prepare destination directory.
    mkdir -p .heroku/python
    mcount "version.python.$PYTHON_VERSION"
    if ! curl "${VENDORED_PYTHON}" -s | tar zxv -C .heroku/python &> /dev/null; then
      puts-warn "Requested runtime ($PYTHON_VERSION) is not available for this stack ($STACK)."
      puts-warn "Aborting.  More info: https://devcenter.heroku.com/articles/python-support"
@@ -121,34 +136,58 @@ if [ ! "$SKIP_INSTALL" ]; then
  # Record for future reference.
  echo "$PYTHON_VERSION" > .heroku/python-version
  echo "$STACK" > .heroku/python-stack
  FRESH_PYTHON=true
  hash -r
 fi
 # Heroku uses the get-pip utility maintained by the Python community to vendor Pip.
 # https://github.com/pypa/get-pip
 GETPIP_URL="https://lang-python.s3.amazonaws.com/etc/get-pip.py"
 GETPIP_PY="${TMPDIR:-/tmp}/get-pip.py"
 if ! curl -s "${GETPIP_URL}" -o "$GETPIP_PY" &> /dev/null; then
    mcount "failure.python.get-pip"
    echo "Failed to pull down get-pip"
    exit 1
 fi
 # If Pip isn't up to date:
 if [ "$FRESH_PYTHON" ] || [[ ! $(pip --version) == *$PIP_UPDATE* ]]; then
  puts-step "Installing pip"
  # Remove old installations.
  rm -fr /app/.heroku/python/lib/python*/site-packages/pip-*
  rm -fr /app/.heroku/python/lib/python*/site-packages/setuptools-*
  /app/.heroku/python/bin/python "$GETPIP_PY" pip=="$PIP_UPDATE" &> /dev/null
  /app/.heroku/python/bin/pip install "$ROOT_DIR/vendor/setuptools-39.0.1-py2.py3-none-any.whl" &> /dev/null
 fi
 set -e
 PIP_VERSION='20.1.1'
 # Must use setuptools <47.2.0 until we fix:
 # https://github.com/heroku/heroku-buildpack-python/issues/1006
 SETUPTOOLS_VERSION='47.1.1'
 WHEEL_VERSION='0.34.2'
 if [[ "${PYTHON_VERSION}" == ${PY34}* ]]; then
  # Python 3.4 support was dropped in pip 19.2+, setuptools 44+ and wheel 0.34+.
  PIP_VERSION='19.1.1'
  SETUPTOOLS_VERSION='43.0.0'
  WHEEL_VERSION='0.33.6'
 elif [[ "${PYTHON_VERSION}" == ${PY27}* || "${PYTHON_VERSION}" == ${PYPY27}* ]]; then
  # Python 2.7 support was dropped in setuptools 45+.
  SETUPTOOLS_VERSION='44.1.1'
 fi
 # We don't use get-pip.py, since:
 #  - it uses `--force-reinstall`, which is unnecessary here and slows down repeat builds
 #  - it means downloading pip twice (once embedded in get-pip.py, and again during
 #    the install, since get-pip.py can't install the embedded version directly)
 #  - we would still have to manage several versions of get-pip.py, to support older Pythons.
 # Instead, we use the pip wheel to install itself, using the method described here:
 # https://github.com/pypa/pip/issues/2351#issuecomment-69994524
 PIP_WHEEL_FILENAME="pip-${PIP_VERSION}-py2.py3-none-any.whl"
 PIP_WHEEL_URL="${S3_BASE_URL}/common/${PIP_WHEEL_FILENAME}"
 PIP_WHEEL="${TMPDIR:-/tmp}/${PIP_WHEEL_FILENAME}"
 if ! curl -sSf "${PIP_WHEEL_URL}" -o "$PIP_WHEEL"; then
  mcount "failure.python.download-pip"
  puts-warn "Failed to download pip"
  exit 1
 fi
 if [[ -f "$BUILD_DIR/Pipfile" ]]; then
  # The buildpack is pinned to old pipenv, which requires older pip.
  # Pip 9.0.2 doesn't support installing itself from a wheel, so we have to use split
  # versions here (ie: installer pip version different from target pip version).
  PIP_VERSION='9.0.2'
  PIP_TO_INSTALL="pip==${PIP_VERSION}"
 else
  PIP_TO_INSTALL="${PIP_WHEEL}"
 fi
 puts-step "Installing pip ${PIP_VERSION}, setuptools ${SETUPTOOLS_VERSION} and wheel ${WHEEL_VERSION}"
 /app/.heroku/python/bin/python "${PIP_WHEEL}/pip" install --quiet --disable-pip-version-check --no-cache \
  "${PIP_TO_INSTALL}" "setuptools==${SETUPTOOLS_VERSION}" "wheel==${WHEEL_VERSION}"
 hash -r
@@ -67,7 +67,6 @@ buildpack_sqlite3_install() {
  puts-step "Installing SQLite3"
  if sqlite3_install "$BUILD_DIR/.heroku/python" ; then
    echo "Sqlite3 successfully installed."
    mcount "success.python.sqlite3"
  else
    echo "Sqlite3 failed to install."
@@ -2,12 +2,13 @@
 shopt -s extglob
 shopt -s nullglob
-# The standard library.
+# This is necessary since this script is sometimes sourced from
-if [[ ! -f  /tmp/stdlib.sh ]]; then
+# subshells that don't have the variables from bin/compile.
-  curl --retry 3 -s https://lang-common.s3.amazonaws.com/buildpack-stdlib/v8/stdlib.sh > /tmp/stdlib.sh
+# Remove this once we no longer wrap all the things in `sub_env`.
-fi
+BIN_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
-# shellcheck source=/dev/null
+ROOT_DIR=$(dirname "${BIN_DIR}")
-source /tmp/stdlib.sh
+# shellcheck source=vendor/buildpack-stdlib_v8.sh
 source "${ROOT_DIR}/vendor/buildpack-stdlib_v8.sh"
 if [ "$(uname)" == Darwin ]; then
    sed() { command sed -l "$@"; }
@@ -95,3 +96,11 @@ python_sqlite3_check() {
  ( python2_check "$VERSION" && version_gte "$VERSION" "$MIN_PYTHON_2" ) \
    || ( python3_check "$VERSION" && version_gte "$VERSION" "$MIN_PYTHON_3" )
 }
 is_module_available() {
  # Returns 0 is the specified module exists, otherwise returns 1.
  # Uses pkgutil rather than pkg_resources or pip's CLI, since pkgutil exists
  # in the stdlib, and doesn't depend on the choice of package manager.
  local module_name="${1}"
  python -c "import sys, pkgutil; sys.exit(0 if pkgutil.find_loader('${module_name}') else 1)"
 }
@@ -12,16 +12,6 @@ old-platform() {
  fi
 }
 pylibmc-missing() {
  if grep -qi 'fatal error: libmemcached/memcached.h: No such file or directory' "$WARNINGS_LOG"; then
    echo
    puts-warn "Hello! There was a problem with your build related to libmemcache."
    puts-warn "The Python library 'pylibmc' must be explicitly specified in 'requirements.txt' in order to build correctly."
    puts-warn "Once you do that, everything should work as expected.   -- Much Love, Heroku."
    mcount 'warnings.libmemcache'
  fi
 }
 scipy-included() {
  if grep -qi 'running setup.py install for scipy' "$WARNINGS_LOG"; then
    echo
@@ -56,11 +46,22 @@ six-included() {
  fi
 }
 gdal-missing() {
  if grep -qi 'Could not find gdal-config' "$WARNINGS_LOG"; then
    mcount 'warnings.gdal'
    echo
    puts-warn "Hello! Package installation failed since the GDAL library was not found."
    puts-warn "For GDAL, GEOS and PROJ support, use the Geo buildpack alongside the Python buildpack:"
    puts-warn "https://github.com/heroku/heroku-geo-buildpack"
    puts-warn "  -- Much Love, Heroku."
  fi
 }
 show-warnings() {
  old-platform
  pylibmc-missing
  scipy-included
  distribute-included
  six-included
  gdal-missing
 }
@@ -1,57 +1,80 @@
 # Python Buildpack Binaries
-## Building the Docker Images
+The binaries for this buildpack are built in Docker containers based on the Heroku stack image.
 **After every change to your formulae, perform the following** from the root of the Git repository (not from `builds/`) to rebuild the images for each stack:
    $ docker build --pull --tag heroku-python-build-cedar-14 --file $(pwd)/builds/cedar-14.Dockerfile .
    $ docker build --pull --tag heroku-python-build-heroku-16 --file $(pwd)/builds/heroku-16.Dockerfile .
    $ docker build --pull --tag heroku-python-build-heroku-18 --file $(pwd)/builds/heroku-18.Dockerfile .
 ## Using the Image
 You can e.g. `bash` into each of the images you built using their tag:
    docker run --rm -ti heroku-python-build-cedar-14 bash
    docker run --rm -ti heroku-python-build-heroku-16 bash
    docker run --rm -ti heroku-python-build-heroku-18 bash
 You then have a shell where you can run `bob build`, `bob deploy`, and so forth. You can of course also invoke these programs directly with `docker run`:
    docker run --rm -ti heroku-python-build-heroku-18 bob build runtimes/python-2.7.15
 In order to `bob deploy`, AWS credentials must be set up, as well as name and prefix of your custom S3 bucket (unless you're deploying to the Heroku production buckets that are pre-defined in each `Dockerfile`); see next section for details.
 ## Configuration
-File `dockerenv.default` contains a list of required env vars; most of these have default values defined in `Dockerfile`. You can copy this file to a location outside the buildpack and modify it with the values you desire and pass its location with `--env-file`, or pass the env vars to `docker run` using `--env`.
+In order to publish binaries AWS credentials must be passed to the build container.
 If you are testing only the build (ie: `bob build`), these are optional.
-Out of the box, each `Dockerfile` has the correct values predefined for `S3_BUCKET`, `S3_PREFIX`, and `S3_REGION`. If you're building your own packages, you'll likely want to change `S3_BUCKET` and `S3_PREFIX` to match your info. Instead of setting `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY` into that file, you may also pass them to `docker run` through the environment, or explicitly using `--env`, in order to prevent accidental commits of credentials.
+In addition, unless you are building the official binaries for Heroku (which use the defaults
 specified in each `Dockerfile`), you will need to override `S3_BUCKET` and `S3_PREFIX` to
 match your own S3 bucket/use case.
-### Passing AWS credentials to the container
+If you only need to set AWS credentials, you can do so by setting the environment variables
 `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY` before calling the make commands.
-If you want to deploy packages and thus need to pass `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY`, you can either pass them explicitly, through your environment, or through an env file.
+For example:
-#### Passing credentials explicitly
+```bash
 set +o history # Disable bash history
 export AWS_ACCESS_KEY_ID=...
 export AWS_SECRET_ACCESS_KEY=...
 set -o history # Re-enable bash history
 make ...
 ```
-    docker run --rm -ti -e AWS_ACCESS_KEY_ID=... -e AWS_SECRET_ACCESS_KEY=... heroku-python-build-heroku-18 bash
+If you need to override the default S3 bucket, or would prefer not to use credentials via
 environment variables, then you need to instead use a Docker env file like so:
-#### Passing credentials through  the environment
+1. Copy the `builds/dockerenv.default` env file to a location outside the buildpack repository.
 2. Edit the new file, adding at a minimum the values for the variables
   `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY` (see Docker
   [env-file documentation](https://docs.docker.com/engine/reference/commandline/run/#set-environment-variables--e---env---env-file)).
 3. Pass the path of the file to the make commands using `ENV_FILE`. For example:
-The two environment variables `AWS_ACCESS_KEY_ID`and `AWS_SECRET_ACCESS_KEY` are defined in `builds/dockerenv.default`, without values. This will cause Docker to "forward" values for these variables from the current environment, so you can pass them in:
+   ```bash
   make ... ENV_FILE=~/.dockerenv.python-buildpack
   ```
-    AWS_ACCESS_KEY_ID=... AWS_SECRET_ACCESS_KEY=... docker run --rm -ti --env-file=builds/dockerenv.default heroku-python-build-heroku-18 bash
+## Launching an interactive build environment
-or
+To start an interactive version of the build environment (ideal for development) use the
 `buildenv` make target, passing in the desired `STACK` name. For example:
-    export AWS_ACCESS_KEY_ID=...
+```bash
-    export AWS_SECRET_ACCESS_KEY=...
+make buildenv STACK=heroku-18
-    docker run --rm -ti --env-file=builds/dockerenv.default heroku-python-build-heroku-18 bash
+```
-#### Passing credentials through a separate env file
+This will create the builder docker image based on the latest image for that stack, and
 then start a bash shell where you can run `bob build`, `bob deploy`, and so forth.
-This method is the easiest for users who want to build packages in their own S3 bucket, as they will have to adjust the `S3_BUCKET` and `S3_PREFIX` environment variable values anyway from their default values.
+The `builds/` directory is bind-mounted into the running container, so local build formula
 changes will appear there immediately without the need to rebuild the image.
-For this method, it is important to keep the credentials file in a location outside the buildpack, so that your credentials aren't accidentally committed. Copy `builds/dockerenv.default` **to a safe location outside the buildpack directory**, and insert your values for `AWS_ACCESS_KEY_ID`and `AWS_SECRET_ACCESS_KEY`.
+## Bulk deploying runtimes
-    docker run --rm -ti --env-file=../SOMEPATHOUTSIDE/s3.env heroku-python-build-heroku-18 bash
+When a new Python version is released, binaries have to be generated for multiple stacks.
 To automate this, use the `deploy-runtimes` make target, which will ensure the builder
 image is up to date, and then run `bob deploy` for each runtime-stack combination.
 The build formula name(s) are passed using `RUNTIMES`, like so:
 ```bash
 make deploy-runtimes RUNTIMES='python-X.Y.Z'
 ```
 By default this will deploy to all supported stacks (see `STACKS` in `Makefile`),
 but this can be overridden using `STACKS`:
 ```bash
 make deploy-runtimes RUNTIMES='python-X.Y.Z' STACKS='heroku-16 heroku-18'
 ```
 Multiple runtimes can also be specified (useful for when adding a new stack), like so:
 ```bash
 make deploy-runtimes RUNTIMES='python-A.B.C python-X.Y.Z' STACKS='heroku-20'
 ```
 Note: Both `RUNTIMES` and `STACKS` are space delimited.
@@ -1,15 +0,0 @@
 FROM heroku/cedar:14
 WORKDIR /app
 ENV WORKSPACE_DIR="/app/builds" \
    S3_BUCKET="lang-python" \
    S3_PREFIX="cedar-14/" \
    DEBIAN_FRONTEND=noninteractive \
    STACK="cedar-14"
 RUN apt-get update && apt-get install -y python-pip libsqlite3-dev realpath && rm -rf /var/lib/apt/lists/*
 COPY requirements.txt /app/
 RUN pip install -r /app/requirements.txt
 COPY . /app
@@ -1,5 +1,8 @@
 # Since no values are specified here, these variables will be read from the environment at run time:
 # https://docs.docker.com/engine/reference/commandline/run/#set-environment-variables--e---env---env-file
 AWS_ACCESS_KEY_ID
 AWS_SECRET_ACCESS_KEY
-S3_BUCKET
+
-S3_PREFIX
+# Uncomment these if you need to override the default S3 bucket and/or path prefixes.
-S3_REGION
+# S3_BUCKET
 # S3_PREFIX
@@ -1,15 +1,20 @@
 FROM heroku/heroku:16-build
 WORKDIR /app
 ENV WORKSPACE_DIR="/app/builds" \
-    S3_BUCKET="lang-python" \
+    S3_BUCKET="heroku-buildpack-python" \
    S3_PREFIX="heroku-16/" \
    DEBIAN_FRONTEND=noninteractive \
    STACK="heroku-16"
-RUN apt-get update && apt-get install -y python-pip libsqlite3-dev && rm -rf /var/lib/apt/lists/*
+RUN apt-get update \
    && DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends -y \
        libsqlite3-dev \
        python3-pip \
        python3-setuptools \
    && rm -rf /var/lib/apt/lists/*
 WORKDIR /app
 COPY requirements.txt /app/
-RUN pip install --disable-pip-version-check --no-cache-dir -r /app/requirements.txt
+RUN pip3 install --disable-pip-version-check --no-cache-dir -r /app/requirements.txt
 COPY . /app
@@ -1,15 +1,20 @@
-FROM heroku/heroku:18-build.v16
+FROM heroku/heroku:18-build
 WORKDIR /app
 ENV WORKSPACE_DIR="/app/builds" \
-    S3_BUCKET="lang-python" \
+    S3_BUCKET="heroku-buildpack-python" \
    S3_PREFIX="heroku-18/" \
    DEBIAN_FRONTEND=noninteractive \
    STACK="heroku-18"
-RUN apt-get update && apt-get install --no-install-recommends -y python-pip-whl=9.0.1-2 python-pip=9.0.1-2 python-setuptools python-wheel libsqlite3-dev && rm -rf /var/lib/apt/lists/*
+RUN apt-get update \
    && DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends -y \
        libsqlite3-dev \
        python3-pip \
        python3-setuptools \
    && rm -rf /var/lib/apt/lists/*
 WORKDIR /app
 COPY requirements.txt /app/
-RUN pip install --disable-pip-version-check --no-cache-dir -r /app/requirements.txt
+RUN pip3 install --disable-pip-version-check --no-cache-dir -r /app/requirements.txt
 COPY . /app
@@ -0,0 +1,20 @@
 FROM heroku/heroku:20-build
 ENV WORKSPACE_DIR="/app/builds" \
    S3_BUCKET="heroku-buildpack-python" \
    S3_PREFIX="heroku-20/" \
    STACK="heroku-20"
 RUN apt-get update \
    && DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends -y \
        libsqlite3-dev \
        python3-pip \
        python3-setuptools \
    && rm -rf /var/lib/apt/lists/*
 WORKDIR /app
 COPY requirements.txt /app/
 RUN pip3 install --disable-pip-version-check --no-cache-dir -r /app/requirements.txt
 COPY . /app
@@ -19,4 +19,4 @@ make install
 # Cleanup
 cd ..
-rm -fr sqlite
+rm -rf sqlite
@@ -1,24 +0,0 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/vendor/
 OUT_PREFIX=$1
 # Use new path, containing autoconf.
 export PATH="/app/.heroku/python/bin/:$PATH"
 hash -r
 echo "Building gdal…"
 VERSION="2.2.1"
 SOURCE_TARBALL="http://download.osgeo.org/gdal/${VERSION}/gdal-${VERSION}.tar.gz"
 curl -L $SOURCE_TARBALL | tar zx
 pushd "gdal-${VERSION}"
 ./configure --prefix=$OUT_PREFIX --enable-static=no  &&
 make
 make install
 # Cleanup
 popd
@@ -1,25 +0,0 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/vendor/
 OUT_PREFIX=$1
 # Use new path, containing autoconf.
 export PATH="/app/.heroku/python/bin/:$PATH"
 hash -r
 echo "Building geos…"
 VERSION=3.6.2
 SOURCE_TARBALL="http://download.osgeo.org/geos/geos-${VERSION}.tar.bz2"
 curl -L $SOURCE_TARBALL | tar xj
 pushd "geos-${VERSION}"
 ./configure --prefix=$OUT_PREFIX --enable-static=no &&
 make
 make install
 # Cleanup
 popd
@@ -1,28 +0,0 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/vendor/
 OUT_PREFIX=$1
 # Skip the build for heroku-16.
 if [[ $S3_PREFIX == "heroku-16" ]]; then
    exit 0
 fi
 # Use new path, containing autoconf.
 export PATH="/app/.heroku/python/bin/:$PATH"
 hash -r
 echo "Building libffi…"
 SOURCE_TARBALL='ftp://sourceware.org/pub/libffi/libffi-3.1.tar.gz'
 curl -L $SOURCE_TARBALL | tar x
 cd libffi-3.1
 ./configure --prefix=$OUT_PREFIX --disable-static &&
 make
 make install
 # Cleanup
 cd ..
@@ -1,45 +0,0 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/vendor/
 OUT_PREFIX=$1
 # Skip the build for heroku-16.
 if [[ $S3_PREFIX == "heroku-16" ]]; then
    exit 0
 fi
 # fail hard
 set -o pipefail
 # fail harder
 set -eux
 DEFAULT_VERSION="1.0.18"
 dep_version=${VERSION:-$DEFAULT_VERSION}
 dep_dirname=libmemcached-${dep_version}
 dep_archive_name=${dep_dirname}.tar.gz
 dep_url=https://launchpad.net/libmemcached/1.0/${dep_version}/+download/${dep_archive_name}
 # SASL Support.
 echo "-----> Building cyrus-sasl 2.1.26…"
 curl -LO ftp://ftp.cyrusimap.org/cyrus-sasl/cyrus-sasl-2.1.26.tar.gz
 # FTP doesn't play well with piping into tar xz
 tar xzf cyrus-sasl-2.1.26.tar.gz
 pushd cyrus-sasl-2.1.26
 ./configure --prefix=${OUT_PREFIX} --with-plugindir=${OUT_PREFIX}lib/sasl2 --with-configdir=${OUT_PREFIX}lib/sasl2
 make -s -j 9
 make install -s
 popd
 echo "-----> Building libmemcached ${dep_version}…"
 curl -L ${dep_url} | tar xz
 pushd ${dep_dirname}
 CPPFLAGS=-I${OUT_PREFIX}/include LDFLAGS=-L${OUT_PREFIX}/lib ./configure --prefix=${OUT_PREFIX} --without-memcached
 make -s -j 9
 make install -s
 popd
 echo "-----> Done."
@@ -1,24 +0,0 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/vendor/
 OUT_PREFIX=$1
 # Use new path, containing autoconf.
 export PATH="/app/.heroku/python/bin/:$PATH"
 hash -r
 echo "Building gdal…"
 VERSION=4.9.3
 SOURCE_TARBALL="http://download.osgeo.org/proj/proj-${VERSION}.tar.gz"
 curl -L $SOURCE_TARBALL | tar zx
 pushd "proj-${VERSION}"
 ./configure --prefix=$OUT_PREFIX --enable-static=no
 make
 make install
 # Cleanup
 popd
@@ -13,11 +13,11 @@ dep_version=${dep_formula##*"/${dep_name}-"} # "subtract" our name from full ver
 dep_package=${dep_name}-v${dep_version} # it's always "pypy2-…"
 dep_dirname=${dep_package}-linux64
 dep_archive_name=${dep_dirname}.tar.bz2
-dep_url=https://bitbucket.org/pypy/pypy/downloads/${dep_archive_name}
+dep_url="https://downloads.python.org/pypy/${dep_archive_name}"
 echo "Building PyPy…"
 echo "${dep_url}"
-curl -L "${dep_url}" | tar jx -C "${OUT_PREFIX}" --strip-components 1 # extract to $OUT_PREFIX, drop the first directory level, which is the archive name
+curl -fL "${dep_url}" | tar jx -C "${OUT_PREFIX}" --strip-components 1 # extract to $OUT_PREFIX, drop the first directory level, which is the archive name
 ln "$OUT_PREFIX/bin/pypy" "$OUT_PREFIX/bin/python"
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/pypy2.7
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/pypy2.7
@@ -13,11 +13,11 @@ dep_version=${dep_formula##*"/${dep_name}-"} # "subtract" our name from full ver
 dep_package=${dep_name}${dep_version_prefix:-}-v${dep_version}${dep_version_suffix:-}
 dep_dirname=${dep_package}-linux64
 dep_archive_name=${dep_dirname}.tar.bz2
-dep_url=https://bitbucket.org/pypy/pypy/downloads/${dep_archive_name}
+dep_url="https://downloads.python.org/pypy/${dep_archive_name}"
 echo "Building PyPy3…"
 echo "${dep_url}"
-curl -L "${dep_url}" | tar jx -C "${OUT_PREFIX}" --strip-components 1 # extract to $OUT_PREFIX, drop the first directory level, which is the archive name
+curl -fL "${dep_url}" | tar jx -C "${OUT_PREFIX}" --strip-components 1 # extract to $OUT_PREFIX, drop the first directory level, which is the archive name
 ln "$OUT_PREFIX/bin/pypy3" "$OUT_PREFIX/bin/python"
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/pypy3.6
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/pypy3.6
@@ -1,27 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
-OUT_PREFIX=$1
+source $(dirname $0)/python2
 BIN_DIR="$(cd "$(dirname "$0")"/../.. || exit; pwd)/bin"
 export BIN_DIR
 # shellcheck source=bin/utils
 source "$BIN_DIR/steps/sqlite3"
 sqlite3_version
 echo "Setting up SQLite3 Headers for $SQLITE3_VERSION"
 sqlite3_install "$OUT_PREFIX" "$SQLITE3_VERSION" 1
 echo "Building Python…"
 SOURCE_TARBALL='https://python.org/ftp/python/2.7.17/Python-2.7.17.tgz'
 curl -L $SOURCE_TARBALL | tar xz
 mv Python-2.7.17 src
 cd src
 ./configure --prefix=$OUT_PREFIX  --enable-unicode=ucs4 --with-ensurepip=no
 make
 make install
 # Remove unneeded test directories, similar to the official Docker Python images:
 # https://github.com/docker-library/python
 find "${OUT_PREFIX}" \( -type d -a \( -name test -o -name tests \) \) -exec rm -rf '{}' +
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python2
@@ -1,32 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
-OUT_PREFIX=$1
+source $(dirname $0)/python3
 BIN_DIR="$(cd "$(dirname "$0")"/../.. || exit; pwd)/bin"
 export BIN_DIR
 # shellcheck source=bin/utils
 source "$BIN_DIR/steps/sqlite3"
 sqlite3_version
 echo "Setting up SQLite3 Headers for $SQLITE3_VERSION"
 sqlite3_install "$OUT_PREFIX" "$SQLITE3_VERSION" 1
 echo "Building Python…"
 SOURCE_TARBALL='https://python.org/ftp/python/3.7.2/Python-3.7.2.tgz'
 curl -L $SOURCE_TARBALL | tar xz
 mv Python-3.7.2 src
 cd src
 ./configure --prefix=$OUT_PREFIX --with-ensurepip=no
 make
 make install
 # Remove unneeded test directories, similar to the official Docker Python images:
 # https://github.com/docker-library/python
 find "${OUT_PREFIX}" \( -type d -a \( -name test -o -name tests \) \) -exec rm -rf '{}' +
 # Remove spare /
 LOCATION=${OUT_PREFIX%?}
 ln $LOCATION/bin/python3 $LOCATION/bin/python
@@ -1,32 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
-OUT_PREFIX=$1
+source $(dirname $0)/python3
 BIN_DIR="$(cd "$(dirname "$0")"/../.. || exit; pwd)/bin"
 export BIN_DIR
 # shellcheck source=bin/utils
 source "$BIN_DIR/steps/sqlite3"
 sqlite3_version
 echo "Setting up SQLite3 Headers for $SQLITE3_VERSION"
 sqlite3_install "$OUT_PREFIX" "$SQLITE3_VERSION" 1
 echo "Building Python…"
 SOURCE_TARBALL='https://python.org/ftp/python/3.4.9/Python-3.4.9.tgz'
 curl -L $SOURCE_TARBALL | tar xz
 mv Python-3.4.9 src
 cd src
 ./configure --prefix=$OUT_PREFIX --with-ensurepip=no
 make
 make install
 # Remove unneeded test directories, similar to the official Docker Python images:
 # https://github.com/docker-library/python
 find "${OUT_PREFIX}" \( -type d -a \( -name test -o -name tests \) \) -exec rm -rf '{}' +
 # Remove spare /
 LOCATION=${OUT_PREFIX%?}
 ln $LOCATION/bin/python3 $LOCATION/bin/python
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -0,0 +1,4 @@
 #!/usr/bin/env bash
 # Build Path: /app/.heroku/python/
 source $(dirname $0)/python3
@@ -1,5 +0,0 @@
 #!/usr/bin/env bash
 sudo apt-get -qq update
 sudo apt-get install software-properties-common
 curl --fail --retry 3 --retry-delay 1 --connect-timeout 3 --max-time 30 https://cli-assets.heroku.com/install-ubuntu.sh | sh
@@ -14,9 +14,9 @@ case "$choice" in
  * ) exit 1;;
 esac
-originMaster=$(git rev-parse origin/master)
+originMain=$(git rev-parse origin/main)
-echo "Tagging commit $originMaster with $newVersion... "
+echo "Tagging commit $originMain with $newVersion... "
-git tag "$newVersion" "${originMaster:?}"
+git tag "$newVersion" "${originMain:?}"
 git push origin refs/tags/$newVersion
 heroku buildpacks:publish "$BP_NAME" "$newVersion"
@@ -31,7 +31,7 @@ if [ $(git tag | grep -q latest-version) ]; then
    echo "Updating latest-version tag"
    git tag -d latest-version
    git push origin :latest-version
-    git tag latest-version "${originMaster:?}"
+    git tag latest-version "${originMain:?}"
    git push --tags
 fi
@@ -1,5 +1,6 @@
 {
  "python": [
-    "heroku/python-getting-started"
+    "heroku/python-getting-started",
    "sharpstone/python_default"
  ]
 }
@@ -1,3 +1,5 @@
 ---
 - - "./repos/python/python-getting-started"
-  - f56b90499ec11e1c9576da2f8c7331300e189db3
+  - main
 - - "./repos/python/python_default"
  - ca947f69027b2a30be5d26f9a42f25e54f4d7a1a
@@ -1,3 +1,6 @@
 # Dependencies for generating/publishing Python binaries.
 bob-builder==0.0.19
 # Sub-dependencies of bob-builder.
 boto==2.49.0
 docopt==0.6.2
 bob-builder
 boto==2.48.0
@@ -0,0 +1,33 @@
 require_relative '../spec_helper'
 describe "Heroku CI" do
  it "works" do
    before_deploy = Proc.new do
      File.open("app.json", "w+") do |f|
        f.puts <<~EOM
          {
            "environments": {
              "test": {
                "scripts": {
                  "test": "nosetests"
                }
              }
            }
          }
        EOM
      end
      run!("echo nose >> requirements.txt")
    end
    Hatchet::Runner.new("python_default", before_deploy: before_deploy).run_ci do |test_run|
      expect(test_run.output).to match("Downloading nose")
      expect(test_run.output).to match("OK")
      test_run.run_again
      expect(test_run.output).to match("installing from cache")
      expect(test_run.output).to_not match("Downloading nose")
    end
  end
 end
@@ -1,10 +1,72 @@
 require_relative '../spec_helper'
-describe "Python!!!!!!!!!!!" do
+describe "Python" do
-  it "🐍" do
+  describe "cache" do
-    Hatchet::Runner.new('python-getting-started', stack: DEFAULT_STACK).deploy do |app|
+    it "functions correctly" do
-      expect(app.output).to           match(/Installing pip/)
+      Hatchet::Runner.new("python_default").deploy do |app|
-      expect(app.run('python -V')).to match(/3.6.10/)
+        expect(app.output).to match(/Installing pip/)
        expect(app.output).to_not match("Requirements file has been changed, clearing cached dependencies")
        expect(app.output).to_not match("No change in requirements detected, installing from cache")
        expect(app.output).to_not match("No such file or directory")
        expect(app.output).to_not match("cp: cannot create regular file")
        # Redeploy with changed requirements file
        run!(%Q{echo "" >> requirements.txt})
        run!(%Q{echo "pygments" >> requirements.txt})
        run!(%Q{git add . ; git commit --allow-empty -m next})
        app.push!
        # Check the cache to have cleared
        expect(app.output).to match("Requirements file has been changed, clearing cached dependencies")
        expect(app.output).to_not match("No dependencies found, preparing to install")
        expect(app.output).to_not match("No change in requirements detected, installing from cache")
        # With no changes on redeploy, the cache should be present
        run!(%Q{git commit --allow-empty -m next})
        app.push!
        expect(app.output).to match("No change in requirements detected, installing from cache")
        expect(app.output).to_not match("Requirements file has been changed, clearing cached dependencies")
        expect(app.output).to_not match("No dependencies found, preparing to install")
      end
    end
  end
  describe "python versions" do
    let(:stack) { ENV["HEROKU_TEST_STACK"] || DEFAULT_STACK }
    it "works with 3.7.6" do
      version = "3.7.6"
      before_deploy = -> { run!(%Q{echo "python-#{version}" >> runtime.txt}) }
      Hatchet::Runner.new("python_default", before_deploy: before_deploy, stack: stack).deploy do |app|
        expect(app.run('python -V')).to match(version)
      end
    end
    it "works with 3.8.2" do
      version = "3.8.2"
      before_deploy = -> { run!(%Q{echo "python-#{version}" >> runtime.txt}) }
      Hatchet::Runner.new("python_default", before_deploy: before_deploy, stack: stack).deploy do |app|
        expect(app.run('python -V')).to match(version)
      end
    end
    it "fails with a bad version" do
      version = "3.8.2.lol"
      before_deploy = -> { run!(%Q{echo "python-#{version}" >> runtime.txt}) }
      Hatchet::Runner.new("python_default", before_deploy: before_deploy, stack: stack, allow_failure: true).deploy do |app|
        expect(app.output).to match("not available for this stack")
      end
    end
  end
  it "getting started app has no relative paths" do
    buildpacks = [
      :default,
      "https://github.com/sharpstone/force_absolute_paths_buildpack"
    ]
    Hatchet::Runner.new("python-getting-started", buildpacks: buildpacks).deploy do |app|
      # Deploy works
    end
  end
 end
@@ -1,4 +1,4 @@
-ENV['HATCHET_BUILDPACK_BASE'] = 'https://github.com/' + ENV['TRAVIS_REPO_SLUG'] + '.git'
+ENV['HATCHET_BUILDPACK_BASE'] = 'https://github.com/heroku/heroku-buildpack-python.git'
 require 'rspec/core'
 require 'rspec/retry'
@@ -15,9 +15,10 @@ RSpec.configure do |config|
  end
 end
-if ENV['TRAVIS']
+DEFAULT_STACK = 'heroku-18'
  # Don't execute tests against "merge" commits
  exit 0 if ENV['TRAVIS_PULL_REQUEST'] != 'false' && ENV['TRAVIS_BRANCH'] == 'master'
 end
-DEFAULT_STACK = 'heroku-16'
+def run!(cmd)
  out = `#{cmd}`
  raise "Error running command #{cmd} with output: #{out}" unless $?.success?
  return out
 end
@@ -0,0 +1 @@
 gdal
@@ -1 +0,0 @@
 django
@@ -0,0 +1,4 @@
 set -euo pipefail
 echo "post_compile ran!"
 echo "post_compile env: $(printenv | cut -d '=' -f 1 | sort | xargs)."
@@ -0,0 +1,4 @@
 set -euo pipefail
 echo "pre_compile ran!"
 echo "pre_compile env: $(printenv | cut -d '=' -f 1 | sort | xargs)."
@@ -1 +0,0 @@
 python-3.6.6
@@ -0,0 +1,2 @@
 pwned-passwords-django==1.4
 Django==2.1
@@ -0,0 +1 @@
 Django==1.11
@@ -6,4 +6,4 @@ verify_ssl = true
 requests = "*"
 [requires]
-python_full_version = "3.6.3"
+python_full_version = "3.7.8"
@@ -1,24 +1,11 @@
 {
    "_meta": {
        "hash": {
-            "sha256": "22a052f4d1cfe6518b2f236fe45c3208c587a9ab1323bdd390632e27278b541e"
+            "sha256": "8a36860f0f9cb55716222098062cea5c5e0f8127cafb9d0c694de327bac9fbc0"
        },
        "host-environment-markers": {
            "implementation_name": "cpython",
            "implementation_version": "3.6.3",
            "os_name": "posix",
            "platform_machine": "x86_64",
            "platform_python_implementation": "CPython",
            "platform_release": "16.7.0",
            "platform_system": "Darwin",
            "platform_version": "Darwin Kernel Version 16.7.0: Thu Jun 15 17:36:27 PDT 2017; root:xnu-3789.70.16~2/RELEASE_X86_64",
            "python_full_version": "3.6.3",
            "python_version": "3.6",
            "sys_platform": "darwin"
        },
        "pipfile-spec": 6,
        "requires": {
-            "python_full_version": "3.6.3"
+            "python_full_version": "3.7.8"
        },
        "sources": [
            {
@@ -1 +1 @@
-pypy2.7-7.2.0
+pypy2.7-7.3.2
@@ -0,0 +1 @@
 pypy2.7-7.3.1
@@ -1 +1 @@
-pypy3.6-7.2.0
+pypy3.6-7.3.2
@@ -0,0 +1 @@
 pypy3.6-7.3.1
@@ -1 +1 @@
-python-2.7.17
+python-2.7.18
@@ -1 +0,0 @@
 requests
@@ -1 +0,0 @@
 python-2.7.99
@@ -1 +0,0 @@
 requests
@@ -1 +0,0 @@
 flask
@@ -1 +0,0 @@
 python-3.4.99
@@ -1 +0,0 @@
 flask
--- a/Show More
+++ b/Show More