heroku-buildpack-python/bin/steps/pylibmc

#!/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`](/).

# The location of the pre-compiled libmemcached binary.
VENDORED_MEMCACHED="https://lang-python.s3.amazonaws.com/$STACK/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
  fi

  LIBMEMCACHED=$(pwd)/vendor
  export LIBMEMCACHED
fi