Create a GitHub Action Using TypeScript

Use this template to bootstrap the creation of a TypeScript action. 🚀

This template includes compilation support, tests, a validation workflow, publishing, and versioning guidance.

If you are new, there's also a simpler introduction in the Hello world JavaScript action repository.

Create Your Own Action

To create your own action, you can use this repository as a template! Just follow the below instructions:

1. Click the Use this template button at the top of the repository
2. Select Create a new repository
3. Select an owner and name for your new repository
4. Click Create repository
5. Clone your new repository

Important

Make sure to remove or update the CODEOWNERS file! For details on how to use this file, see About code owners.

Initial Setup

After you've cloned the repository to your local machine or codespace, you'll need to perform some initial setup steps before you can develop your action.

Note

You'll need to have a reasonably modern version of Node.js handy (20.x or later should work!). If you are using a version manager like nodenv or fnm, this template has a .node-version file at the root of the repository that can be used to automatically switch to the correct version when you cd into the repository. Additionally, this .node-version file is used by GitHub Actions in any actions/setup-node actions.

1. 🛠️ Install the dependencies

   npm install

2. 🏗️ Package the TypeScript for distribution

   npm run bundle

3. ✅ Run the tests

   $ npm test
   
   PASS  ./index.test.js
     ✓ throws invalid number (3ms)
     ✓ wait 500 ms (504ms)
     ✓ test runs (95ms)
   
   ...

Update the Action Metadata

The action.yml file defines metadata about your action, such as input(s) and output(s). For details about this file, see Metadata syntax for GitHub Actions.

When you copy this repository, update action.yml with the name, description, inputs, and outputs for your action.

Update the Action Code

The src/ directory is the heart of your action! This contains the source code that will be run when your action is invoked. You can replace the contents of this directory with your own code.

There are a few things to keep in mind when writing your action code:

• Most GitHub Actions toolkit and CI/CD operations are processed asynchronously. In main.ts, you will see that the action is run in an async function.

  import * as core from '@actions/core'
  //...
  
  async function run() {
    try {
      //...
    } catch (error) {
      core.setFailed(error.message)
    }
  }

  For more information about the GitHub Actions toolkit, see the documentation.

So, what are you waiting for? Go ahead and start customizing your action!

1. Create a new branch

   git checkout -b releases/v1

2. Replace the contents of src/ with your action code

3. Add tests to __tests__/ for your source code

4. Format, test, and build the action

   npm run all

   This step is important! It will run ncc to build the final JavaScript action code with all dependencies included. If you do not run this step, your action will not work correctly when it is used in a workflow. This step also includes the --license option for ncc, which will create a license file for all of the production node modules used in your project.

5. (Optional) Test your action locally

   The @github/local-action utility can be used to test your action locally. It is a simple command-line tool that "stubs" (or simulates) the GitHub Actions Toolkit. This way, you can run your TypeScript action locally without having to commit and push your changes to a repository.

   The local-action utility can be run in the following ways:

   • Visual Studio Code Debugger

     Make sure to review and, if needed, update .vscode/launch.json

   • Terminal/Command Prompt

     # npx local action <action-yaml-path> <entrypoint> <dotenv-file>
     npx local-action . src/main.ts .env

   You can provide a .env file to the local-action CLI to set environment variables used by the GitHub Actions Toolkit. For example, setting inputs and event payload data used by your action. For more information, see the example file, .env.example, and the GitHub Actions Documentation.

6. Commit your changes

   git add .
   git commit -m "My first action is ready!"

7. Push them to your repository

   git push -u origin releases/v1

8. Create a pull request and get feedback on your action

9. Merge the pull request into the main branch

Your action is now published! 🚀

For information about versioning your action, see Versioning in the GitHub Actions toolkit.

Validate the Action

You can now validate the action by referencing it in a workflow file. For example, ci.yml demonstrates how to reference an action in the same repository.

steps:
  - name: Checkout
    id: checkout
    uses: actions/checkout@v4

  - name: Test Local Action
    id: test-action
    uses: ./
    with:
      milliseconds: 1000

  - name: Print Output
    id: output
    run: echo "${{ steps.test-action.outputs.time }}"

For example workflow runs, check out the Actions tab! 🚀

Usage

After testing, you can create version tag(s) that developers can use to reference different stable versions of your action. For more information, see Versioning in the GitHub Actions toolkit.

To include the action in a workflow in another repository, you can use the uses syntax with the @ symbol to reference a specific branch, tag, or commit hash.

steps:
  - name: Checkout
    id: checkout
    uses: actions/checkout@v4

  - name: Test Local Action
    id: test-action
    uses: actions/typescript-action@v1 # Commit with the `v1` tag
    with:
      milliseconds: 1000

  - name: Print Output
    id: output
    run: echo "${{ steps.test-action.outputs.time }}"

Publishing a New Release

This project includes a helper script, script/release designed to streamline the process of tagging and pushing new releases for GitHub Actions.

GitHub Actions allows users to select a specific version of the action to use, based on release tags. This script simplifies this process by performing the following steps:

1. Retrieving the latest release tag: The script starts by fetching the most recent SemVer release tag of the current branch, by looking at the local data available in your repository.
2. Prompting for a new release tag: The user is then prompted to enter a new release tag. To assist with this, the script displays the tag retrieved in the previous step, and validates the format of the inputted tag (vX.X.X). The user is also reminded to update the version field in package.json.
3. Tagging the new release: The script then tags a new release and syncs the separate major tag (e.g. v1, v2) with the new release tag (e.g. v1.0.0, v2.1.2). When the user is creating a new major release, the script auto-detects this and creates a releases/v# branch for the previous major version.
4. Pushing changes to remote: Finally, the script pushes the necessary commits, tags and branches to the remote repository. From here, you will need to create a new release in GitHub so users can easily reference the new tags in their workflows.