Merge pull request #925 from heroku/reproduce/cache-busting

Fix cache clear on redeploy

.gitignore

@@ -10,3 +10,5 @@ buildpack/*
 
 builds/dockerenv.staging*
 builds/dockerenv.production
+
+test/scratch

.travis.yml

@@ -10,11 +10,11 @@ before_script:
 
 script:
   - docker build --pull --tag travis-build-cedar-14 --file $(pwd)/builds/cedar-14.Dockerfile .
-  - docker run --rm -e "STACK=cedar-14" -e "USE_STAGING_BINARIES=$USE_STAGING_BINARIES" travis-build-cedar-14 bash $TESTFOLDER
+  - docker run --rm -e "STACK=cedar-14" 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 run --rm -e "STACK=heroku-16" 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
+  - docker run --rm -e "STACK=heroku-18" travis-build-heroku-18 bash $TESTFOLDER
 
 jobs:
   include:

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 # Master
 
+- Add failcase for cache busting
+- Bugfix: Clearing pip dependencies
 - Correct ftp to https in vendored file
 - Warn for Django 1.11 approaching EOL, provide link to roadmap
 

bin/compile

@@ -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

bin/steps/README.MD

@@ -0,0 +1,28 @@
+# Python Buildpack Install Steps
+
+TODO: Add context on Python install steps, such as why symlinking vs copying
+
+## Installing the Pip tool
+
+The Python Buildpack uses a tool called `get-pip` to install the pip tool. This
+is done in the `python` script.
+
+This is in part because Python historically did not come with pip by default.
+
+## 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.

bin/steps/pip-install

@@ -47,6 +47,7 @@ if [ ! "$SKIP_PIP_INSTALL" ]; then
     if [ ! -f "$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="${PIPESTATUS[0]}"
     set -e
@@ -58,12 +59,9 @@ if [ ! "$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

bin/steps/python

@@ -86,14 +86,6 @@ if [[ "$STACK" != "$CACHED_PYTHON_STACK" ]]; then
     rm -fr .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"
@@ -103,6 +95,29 @@ if [ -f .heroku/python-version ]; then
   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" "$CACHE_DIR/.heroku/requirements.txt"
+  # If we don't already have a python version, this is a new app
+  if [ -f .heroku/python-version ]; then
+    puts-step "Clearing cached dependencies"
+    # if there are any differences, clear the Python cache
+    # Installing Python over again does not take noticably more time
+    rm -rf .heroku/python
+    unset SKIP_INSTALL
+  fi
+else
+  # IF there IS a cached directory, check for differences with the new one
+  if ! diff "$BUILD_DIR/requirements.txt" "$CACHE_DIR/.heroku/requirements.txt"; then
+    puts-step "Clearing cached dependencies"
+    # if there are any differences, clear the Python cache
+    # Installing Python over again does not take noticably more time
+    rm -rf .heroku/python
+    unset SKIP_INSTALL
+  fi
+fi
 
 if [ ! "$SKIP_INSTALL" ]; then
     puts-step "Installing $PYTHON_VERSION"
@@ -137,7 +152,7 @@ if ! curl -s "${GETPIP_URL}" -o "$GETPIP_PY" &> /dev/null; then
     exit 1
 fi
 
-# If Pip isn't up to date:
+# If a new Python has been installed or Pip isn't up to date:
 if [ "$FRESH_PYTHON" ] || [[ ! $(pip --version) == *$PIP_UPDATE* ]]; then
 
   puts-step "Installing pip"

spec/hatchet/python_spec.rb

@@ -1,10 +1,28 @@
 require_relative '../spec_helper'
 
-describe "Python!!!!!!!!!!!" do
+describe "Default Python Deploy" do
   it "🐍" do
     Hatchet::Runner.new('python-getting-started', stack: DEFAULT_STACK).deploy do |app|
       expect(app.output).to           match(/Installing pip/)
       expect(app.run('python -V')).to match(/3.6.10/)
+
+
+      expect(app.output).to_not match("Clearing cached dependencies")
+
+      # Redeploy
+      run!(%Q{echo "flask" >> requirements.txt})
+      run!(%Q{git add . ; git commit --allow-empty -m next})
+      app.push!
+
+      # Check for the cache tohave cleared
+      expect(app.output).to match("Clearing cached dependencies")
+
+      run!(%Q{git commit --allow-empty -m next})
+      app.push!
+
+      # The cache should not clear with no changes
+      expect(app.output).to_not match("Clearing cached dependencies")
+
     end
   end
 end

spec/spec_helper.rb

@@ -20,4 +20,10 @@ if ENV['TRAVIS']
   exit 0 if ENV['TRAVIS_PULL_REQUEST'] != 'false' && ENV['TRAVIS_BRANCH'] == 'master'
 end
 
-DEFAULT_STACK = 'heroku-16'
+DEFAULT_STACK = 'heroku-18'
+
+def run!(cmd)
+  out = `#{cmd}`
+  raise "Error running command #{cmd} with output: #{out}" unless $?.success?
+  return out
+end