About custom actions

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

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. Los ejecutores auto-hospedados deberán utilizar un sistema operativo Linux y tener Docker instalado para ejecutar las acciones de contenedores de Docker. Para más información sobre los requisitos de los ejecutores autohospedados, consulta Ejecutores autohospedados.

JavaScript actions

JavaScript actions can run directly on a runner machine, and separate the action code from the environment used to run the code. Using a JavaScript action simplifies the action code and executes faster than a Docker container action.

Para garantizar que tus acciones de JavaScript son compatibles con todos los ejecutores hospedados en GitHub (Ubuntu, Windows, y macOS), el código empaquetado de JavaScript que escribas debe ser puramente JavaScript y no depender de otros binarios. Las acciones de JavaScript se ejecutan directamente en el ejecutor y utiliza binarios que ya existen en la imagen del ejecutor.

If you're developing a Node.js project, the GitHub Actions Toolkit provides packages that you can use in your project to speed up development. For more information, see the actions/toolkit repository.

Composite Actions

A composite action allows you to combine multiple workflow steps within one action. For example, you can use this feature to bundle together multiple run commands into an action, and then have a workflow that executes the bundled commands as a single step using that action. To see an example, check out Creating a composite action.

Next steps

To learn about how to manage your custom actions, see Managing custom actions.