toolkit/docs/container-action.md

Creating a Docker Action

The container-template repo contains the base files to create a Docker action.

Create a Repo from the Template

Navigate to https://github.com/actions/container-template

Click on Use this template to create the repo for your action.

Complete creating your repo and clone the repo.

NOTE: The location of the repo will be how users will reference your action in their workflow file with the using keyword.

e.g. To use https://github.com/actions/setup-node, users will author:

steps:
    using: actions/setup-node@v4

Define Metadata

Your action has a name and a description. Update the author.

Create inputs that your unit of work will need. These will be what workflow authors set with the with: keyword.

name: 'My Container Action'
description: 'Get started with Container actions'
author: 'GitHub'
inputs: 
  myInput:
    description: 'Input to use'
    default: 'world'
runs:
  using: 'docker'
  image: 'Dockerfile'
  args:
    - ${{ inputs.myInput }}

It will be run with docker and the input is mapped into the args

Change Code

The entry point is in entrypoint.sh

#!/bin/sh -l

echo "hello $1"

Publish

Simply push your action to publish.

$ git push

The runner will download the action and build the docker container on the fly at runtime.

Consider versioning your actions with tags. See versioning