env-map-buildpack

Allows for customised flattening of env vars in Cloud Foundry VCAP_SERVICES based on jq selectors. Requires a stack with jq already installed.

NB: This is intended only for situations where high levels of customisation are needed e.g. 3rd party software. For most situations, the pancake-buildpack is likely a better option.

Background

When using Cloud Foundry, services such as databases are provided by service bindings using the Open Service Broker API. The credentials, URLs etc. of these services are placed into a JSON formatted environment variable called VCAP_SERVICES. To consume these credentials applications typically either include code to parse the JSON or use custom entry scripts.

This buildpack utilizes the profile.d directory to supply a script that will export environment variables based on a selectors using the popular jq binary. Any scripts present in the profile.d directory will be sourced when the application starts up.

Usage

To use this buildpack, include https://github.com/andy-paine/env-map-buildpack anywhere but the last element in the buildpacks field in your Cloud Foundry manifest:

buildpacks:
  - https://github.com/andy-paine/env-map-buildpack
  - python_buildpack

Include an env-map.yml file in the directory which you cf push - see examples directory for full details.

Any selector which works when performing echo "$VCAP_SERVICES" | jq '<selector>' will work with this buildpack.

This buildpack does not attempt to resolve situations such as multiple results returned by selector or invalid selectors.

To use an alternative file name/location, set ENV_MAP_BP_CONFIG to the path of your config file relative to the root of the app which is pushed

JSON/offline mode

To make configuration easier, YAML is the default configuration format. To parse this format, the buildpack downloads and uses yq. For users who cannot download external binaries or for users who prefer JSON for configuration, you can provide a mapping file in JSON format with a .json extension. This will skip downloading yq and so should work on security concious/air-gapped environments.

To instruct the buildpack to use a JSON formatted file, use the ENV_MAP_BP_CONFIG environment variable detailed above.