#!/usr/bin/env bash

# This script serves as the

# [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)

# compiler.

#

# A [buildpack](http://devcenter.heroku.com/articles/buildpacks) is an

# adapter between a Python application and Heroku's runtime.

#

# You can intreract with the Heroku API directly with [heroku.py](https://github.com/heroku/heroku.py/).

#

# See also: [Release history](/changelog.html), [Detection](/detect.html).

#

# ## Usage

# Compiling an app into a slug is simple:

#

# $ bin/compile <build-dir> <cache-dir>

# ## Assumptions

#

# This buildpack makes the following assumptions:

#

# - The desired Python VM is available on the base system.

# - Library dependencies are available on the base system.

# - Django applications should not require any platform-specific configuration.

# <hr />

# ## Context

# Fail fast and fail hard.

set -eo pipefail

# Prepend proper path for virtualenv hackery. This will be deprecated soon.

export PATH=:/usr/local/bin:$PATH

# Paths.

BIN_DIR=$(cd $(dirname $0); pwd) # absolute path

ROOT_DIR=$(dirname $BIN_DIR)

BUILD_DIR=$1

CACHE_DIR=$2

# The detected application type (`Python`|`Python/Django`).

NAME=$($BIN_DIR/detect $BUILD_DIR)

# Where to store the Pip download cache.

CACHED_DIRS=".heroku"

PIP_DOWNLOAD_CACHE=${PIP_DOWNLOAD_CACHE:-$CACHE_DIR/pip_downloads}

# Static configurations for virtualenv caches.

LEGACY_VIRTUALENV_LOC="."

MODERN_VIRTUALENV_LOC=".heroku/venv"

LEGACY_VIRTUALENV_DIRS="bin include lib"

LEGACY_VIRTUALENV_TRIGGER="lib/python2.7"

# Python version. This will be used in the future to specify custom Pythons.

PYTHON_VERSION="2.7.2"

PYTHON_EXE="python2.7"

# Sanitizing environment variables.

unset GIT_DIR

unset PYTHON_HOME

unset PYTHONPATH

# We'll need to send these statics to other scripts we `source`.

export PIP_DOWNLOAD_CACHE BUILD_DIR CACHE_DIR BIN_DIR

# Syntax sugar.

indent() {

RE="s/^/ /"

[ $(uname) == "Darwin" ] && sed -l "$RE" || sed -u "$RE"

}

function virtualenv (){

python "$ROOT_DIR/vendor/virtualenv-1.7/virtualenv.py" "$@"

}

function puts-step (){

echo "-----> $@"

}

function puts-warn (){

echo " ! $@"

}

# ## Build Time

#

# Switch to the repo's context.

cd $BUILD_DIR

# Experimental pre_compile hook.

source $BIN_DIR/steps/hooks/pre_compile

# ### Sanity Checks

#

# Just a little peace of mind.

# If no requirements given, assume `setup.py develop`.

if [ ! -f requirements.txt ]; then

puts-step "No requirements.txt provided; assuming dist package."

echo "-e ." > requirements.txt

fi

# ### The Cache

mkdir -p $CACHE_DIR

# Nice defaults.

LEGACY_VIRTUALENV=false

VIRTUALENV_LOC=$MODERN_VIRTUALENV_LOC

# Support "old-style" virtualenvs.

if [ -d $CACHE_DIR/$LEGACY_VIRTUALENV_TRIGGER ]; then

LEGACY_VIRTUALENV=true

VIRTUALENV_LOC=$LEGACY_VIRTUALENV_LOC

CACHED_DIRS=$LEGACY_VIRTUALENV_DIRS

# Warn for a checked-in virtualenv.

if [ -d "lib" ] || [ -d "bin" ]; then

puts-warn "You have a virtualenv checked in. You should ignore the appropriate paths in your repo. See http://devcenter.heroku.com/articles/gitignore for more info.";

fi

# Reject a conflicting checked-in virtualenv.

if [ -f "lib/python2.7" ]; then

puts-warn "Checked-in virtualenv conflict."

exit 1;

fi

fi

# Restore old artifacts from the cache.

for dir in $CACHED_DIRS; do

cp -R $CACHE_DIR/$dir . &> /dev/null || true

done

set +e

# Create set-aside `.heroku` folder.

mkdir .heroku &> /dev/null

HEROKU_DIR_STATUS=$?

# This is a new app, disable injection.

[ $HEROKU_DIR_STATUS -eq 0 ] && {

touch .heroku/injection_disabled

}

set -e

# ### Virtualenv Setup

#

# Create the virtualenv. Rebuild if corrupt.

# TODO: Bootstrap a bottled Python VM...

set +e

puts-step "Preparing Python interpreter ($PYTHON_VERSION)"

puts-step "Creating Virtualenv version $(virtualenv --version)"

# Try to create the virtualenv.

OUT=$(virtualenv --python $PYTHON_EXE --distribute --never-download --prompt='(venv) ' $VIRTUALENV_LOC 2>&1)

# If there's an error, purge and recreate.

[ $? -ne 0 ] && {

puts-warn "Virtualenv corrupt, rebuilding."

for dir in $VIRTUALENV_DIRS; do

rm -fr $dir &> /dev/null || true

done

OUT=$(virtualenv --python $PYTHON_EXE --distribute --never-download --prompt='(venv) ' $VIRTUALENV_LOC )

}

echo "$OUT" | indent

set -e

# Pylibmc support.

# See [`bin/steps/pylibmc`](pylibmc.html).

source $BIN_DIR/steps/pylibmc

# Activate the Virtualenv.

puts-step "Activating virtualenv"

source $VIRTUALENV_LOC/bin/activate

# Install Mercurial if it appears to be required.

if (grep -Fiq "hg+" requirements.txt) then

pip install --use-mirrors mercurial | indent

fi

# Install dependencies with Pip.

puts-step "Installing dependencies using pip version $(pip --version | awk '{print $2}')"

pip install --use-mirrors -r requirements.txt --src ./.heroku/src | indent

# Do additional application hackery if applications appears to be a Django app.

# Optionally, disable all Django-specific changes with `DISABLE_INJECTION` env.

#

# See [`bin/steps/django`](django.html).

if [ "$NAME" = "Python/Django" ]; then

source $BIN_DIR/steps/django/init

fi

# Make Virtualenv's paths relative for portability.

set +e

OUT=$(virtualenv --python $PYTHON_EXE --relocatable $VIRTUALENV_LOC)

[ $? -ne 0 ] && {

puts-warn "Error making virtualenv relocatable"

echo "$OUT" | indent

exit 1

}

set -e

# ### Finalize

#

# Store new artifacts in cache.

for dir in $CACHED_DIRS; do

rm -rf $CACHE_DIR/$dir

cp -R $dir $CACHE_DIR/

done

# ### Fin.

# Experimental post_compile hook.

source $BIN_DIR/steps/hooks/post_compile

# <a href="http://github.com/heroku/heroku-buildpack-python"><img style="position: absolute; top: 0; right: 0; border: 0;" src="https://d3nwyuy0nl342s.cloudfront.net/img/7afbc8b248c68eb468279e8c17986ad46549fb71/687474703a2f2f73332e616d617a6f6e6177732e636f6d2f6769746875622f726962626f6e732f666f726b6d655f72696768745f6461726b626c75655f3132313632312e706e67" alt="Fork me on GitHub"></a>