Note: GitHub-hosted runners are not currently supported on GitHub Enterprise Server. You can see more information about planned future support on the GitHub public roadmap.
About custom actions
You can create actions by writing custom code that interacts with your repository in any way you'd like, including integrating with GitHub's APIs and any publicly available third-party API. For example, an action can publish npm modules, send SMS alerts when urgent issues are created, or deploy production-ready code.
Actions can run directly on a machine or in a Docker container. You can define an action's inputs, outputs, and environment variables.
Types of actions
You can build Docker container and JavaScript actions. Actions require a metadata file to define the inputs, outputs and main entrypoint for your action. The metadata filename must be either action.yml or action.yaml. For more information, see "Metadata syntax for GitHub Actions."
| Type | Operating system |
|---|---|
| Docker container | Linux |
| JavaScript | Linux, macOS, Windows |
| Composite Actions | Linux, macOS, Windows |
Docker container actions
Docker containers package the environment with the GitHub Actions code. This creates a more consistent and reliable unit of work because the consumer of the action does not need to worry about the tools or dependencies.
A Docker container allows you to use specific versions of an operating system, dependencies, tools, and code. For actions that must run in a specific environment configuration, Docker is an ideal option because you can customize the operating system and tools. Because of the latency to build and retrieve the container, Docker container actions are slower than JavaScript actions.
Docker container actions can only execute on runners with a Linux operating system. Self-hosted runners must use a Linux operating system and have Docker installed to run Docker container actions. For more information about the requirements of self-hosted runners, see "