command-function-buildpack

README

command-function-buildpack

The Command Function Buildpack is a Cloud Native Buildpack V3 that provides riff Command Function Invoker to functions.

This buildpack is designed to work in collaboration with other buildpacks, which are tailored to support (and know how to build / run) languages supported by riff.

In Plain English

In a nutshell, when combined with the other buildpacks present in the riff builder what this means (and especially when dealing with the riff CLI which takes care of the creation of the riff.toml file for you):

• The fact that the --artifact flag points to a file with the execute permission will result in the execution as a command function, thanks to the command invoker
• Ambiguity in the detection process will result in a build failure
• The presence of the --invoker flag will entirely bypass the detection mechanism and force a given language/invoker

Detailed Buildpack Behavior

Detection Phase

Detection passes if

• a $APPLICATION_ROOT/riff.toml exists and
• the file pointed to by the artifact value in riff.toml exists and is executable

If detection passes, the buildpack will add a riff-invoker-command key and command metadata extracted from the riff metadata.

If several languages are detected simultaneously, the detect phase errors out. The override key in riff.toml can be used to bypass detection and force the use of a particular invoker.

Build Phase

If a command function has been selected

• Contributes the riff Command Invoker to a launch layer, set as the main executable with FUNCTION_URI = <artifact> set as an environment variable.

The function behavior is exposed via standard buildpack process types:

• Contributes web process
• Contributes function process

How to Build

Prerequisites

To build the command-function-buildpack you'll need

• Go 1.13+
• to run acceptance tests:
  • a running local docker daemon
• for local function builds
  • the pack command line tool

You can build the buildpack by running

make

This will package (with pre-downloaded cache layers) the buildpack in the artifactory/io/projectriff/command/io.projectriff.command/latest directory. That can be used as a uri in a builder.toml file of a builder (see https://github.com/projectriff/builder)

License

This buildpack is released under version 2.0 of the Apache License.