Developing a third party CLI action

Learn how to develop an action to set up a CLI on GitHub Actions runners.

Introduction

You can write an action to provide a way for users to access your servers via a configured CLI environment on GitHub Actions runners.

Your action should:

  • Make it simple for users to specify the version of the CLI to install
  • Support multiple operating systems
  • Run in an efficient fashion to minimize run-time and associated costs
  • Work across GitHub-hosted and self-hosted runners
  • Leverage community tooling when possible

This article will demonstrate how to write an action that retrieves a specific version of your CLI, installs it, adds it to the path, and (optionally) caches it. This type of action (an action that sets up a tool) is often named setup-$TOOL.

Prerequisites

You should have an understanding of how to write a custom action. For more information, see "About custom actions". For a more detailed guide on how to write a custom action, see "Creating a JavaScript action."

Example

The following script demonstrates how you can get a user-specified version as input, download and extract the specific version of your CLI, then add the CLI to the path.

GitHub provides actions/toolkit, which is a set of packages that helps you create actions. This example uses the actions/core and actions/tool-cache packages.

JavaScript
const core = require('@actions/core');
const tc = require('@actions/tool-cache');

async function setup() {
  // Get version of tool to be installed
  const version = core.getInput('version');

  // Download the specific version of the tool, e.g. as a tarball
  const pathToTarball = await tc.downloadTool(getDownloadURL());

  // Extract the tarball onto the runner
  const pathToCLI = await tc.extractTar(pathToTarball);

  // Expose the tool by adding it to the PATH
  core.addPath(pathToCLI)
}

module.exports = setup

To use this script, replace getDownloadURL with a function that downloads your CLI. You will also need to create an actions metadata file (action.yml) that accepts a version input and that runs this script. For full details about how to create an action, see "Creating a JavaScript action."

For a full example of how to set up this action, see example-setup-gh.

Further reading

This pattern is employed in several actions. For more examples, see:

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