heroku-buildpack-python/bin/detect

#!/usr/bin/env bash

# This script serves as the
# [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
# detector.
#
# A [buildpack](http://devcenter.heroku.com/articles/buildpacks) is an
# adapter between a Python application and Heroku's runtime.

# ## Usage
# Compiling an app into a slug is simple:
#
#     $ bin/detect <build-dir> <cache-dir>

BUILD_DIR=$1

# Exit early if app is clearly not Python.
if [ ! -f $BUILD_DIR/requirements.txt ] && [ ! -f $BUILD_DIR/setup.py ]; then
  exit 1
fi

# If only `setup.py`, assume that the app is not Django.
if [ ! -f $BUILD_DIR/requirements.txt ]; then
  echo Python
  exit 0
fi

# `Python/Django` if `**/settings.py` is present and `django` exists in
# `requirements.txt`.
#
# Otherwise, `Python`.

array=""
list_requirements() {
IFS_BAK=$IFS
IFS="
"
    requirement_file=$1
    reqs=$(cat $requirement_file)
    for req in $reqs; do
        if [[ $req == -r* ]]; then
            new_req=$(echo $req | cut -d" " -f2)
            if [[ $new_req == $1 ]]; then
                continue
            fi
            directory=$(dirname $requirement_file)
            if [[ ! $array == *$directory/$new_req* ]]; then
                list_requirements "$directory/$new_req"
            fi
            array="$array $directory/$new_req"
        else
            echo $req;
        fi

    done
IFS=$IFS_BAK
IFS_BAK=
}


SETTINGS_FILE=$(find $BUILD_DIR/. -maxdepth 2 -type f -name 'settings.py' | head -1)


[ -n "$SETTINGS_FILE" ] && ( list_requirements $BUILD_DIR/requirements.txt | grep -Fiq "django" ) && echo Python/Django || echo Python