Creating a JavaScript action

In this tutorial, you'll learn how to build a JavaScript action using the actions toolkit.

이 문서의 내용

Introduction

In this guide, you'll learn about the basic components needed to create and use a packaged JavaScript action. To focus this guide on the components needed to package the action, the functionality of the action's code is minimal. The action prints "Hello World" in the logs or "Hello [who-to-greet]" if you provide a custom name.

This guide uses the GitHub Actions Toolkit Node.js module to speed up development. For more information, see the actions/toolkit repository.

Once you complete this project, you should understand how to build your own JavaScript action and test it in a workflow.

JavaScript 작업이 모든 GitHub 호스트된 실행기(Ubuntu, Windows 및 macOS)와 호환되도록 하려면 작성하는 패키지된 JavaScript 코드는 순수 JavaScript이고 다른 이진 파일에 의존하지 않아야 합니다. JavaScript 작업은 실행기에서 직접 실행되며 실행기 이미지에 이미 있는 이진 파일을 사용합니다.

경고

워크플로와 작업을 만들 때는 코드가 공격자의 신뢰할 수 없는 입력을 실행할 수 있는지 항상 고려해야 합니다. 특정 컨텍스트는 공격자가 자신의 악성 콘텐츠를 삽입할 수 있으므로 신뢰할 수 없는 입력으로 취급해야 합니다. 자세한 내용은 GitHub Actions에 대한 보안 강화을(를) 참조하세요.

Prerequisites

Before you begin, you'll need to download Node.js and create a public GitHub repository.

  1. Download and install Node.js 20.x, which includes npm.

    https://nodejs.org/en/download/

  2. Create a new public repository on GitHub and call it "hello-world-javascript-action". For more information, see 새 리포지토리 만들기.

  3. Clone your repository to your computer. For more information, see 리포지토리 복제.

  4. From your terminal, change directories into your new repository.

    Shell
    cd hello-world-javascript-action

  5. From your terminal, initialize the directory with npm to generate a package.json file.

    Shell
    npm init -y

Creating an action metadata file

Create a new file named action.yml in the hello-world-javascript-action directory with the following example code. For more information, see GitHub Actions에 대한 메타데이터 구문.

YAML
name: Hello World
description: Greet someone and record the time

inputs:
  who-to-greet: # id of input
    description: Who to greet
    required: true
    default: World

outputs:
  time: # id of output
    description: The time we greeted you

runs:
  using: node20
  main: dist/index.js

This file defines the who-to-greet input and time output. It also tells the action runner how to start running this JavaScript action.

Adding actions toolkit packages

The actions toolkit is a collection of Node.js packages that allow you to quickly build JavaScript actions with more consistency.

The toolkit @actions/core package provides an interface to the workflow commands, input and output variables, exit statuses, and debug messages.

The toolkit also offers a @actions/github package that returns an authenticated Octokit REST client and access to GitHub Actions contexts.

The toolkit offers more than the core and github packages. For more information, see the actions/toolkit repository.

At your terminal, install the actions toolkit core and github packages.

Shell
npm install @actions/core @actions/github

You should now see a node_modules directory and a package-lock.json file which track any installed dependencies and their versions. You should not commit the node_modules directory to your repository.

Writing the action code

This action uses the toolkit to get the who-to-greet input variable required in the action's metadata file and prints "Hello [who-to-greet]" in a debug message in the log. Next, the script gets the current time and sets it as an output variable that actions running later in a job can use.

GitHub Actions provide context information about the webhook event, Git refs, workflow, action, and the person who triggered the workflow. To access the context information, you can use the github package. The action you'll write will print the webhook event payload to the log.

Add a new file called src/index.js, with the following code.

JavaScript
import * as core from "@actions/core";
import * as github from "@actions/github";

try {
  // `who-to-greet` input defined in action metadata file
  const nameToGreet = core.getInput("who-to-greet");
  core.info(`Hello ${nameToGreet}!`);

  // Get the current time and set it as an output variable
  const time = new Date().toTimeString();
  core.setOutput("time", time);

  // Get the JSON webhook payload for the event that triggered the workflow
  const payload = JSON.stringify(github.context.payload, undefined, 2);
  core.info(`The event payload: ${payload}`);
} catch (error) {
  core.setFailed(error.message);
}

If an error is thrown in the above index.js example, core.setFailed(error.message); uses the actions toolkit @actions/core package to log a message and set a failing exit code. For more information, see 작업의 종료 코드 설정.

Creating a README

To let people know how to use your action, you can create a README file. A README is most helpful when you plan to share your action publicly, but is also a great way to remind you or your team how to use the action.

In your hello-world-javascript-action directory, create a README.md file that specifies the following information:

  • A detailed description of what the action does.
  • Required input and output arguments.
  • Optional input and output arguments.
  • Secrets the action uses.
  • Environment variables the action uses.
  • An example of how to use your action in a workflow.
Markdown
# Hello world JavaScript action

This action prints "Hello World" or "Hello" + the name of a person to greet to the log.

## Inputs

### `who-to-greet`

**Required** The name of the person to greet. Default `"World"`.

## Outputs

### `time`

The time we greeted you.

## Example usage

```yaml
uses: actions/hello-world-javascript-action@e76147da8e5c81eaf017dede5645551d4b94427b
with:
  who-to-greet: Mona the Octocat
```

Commit, tag, and push your action

GitHub downloads each action run in a workflow during runtime and executes it as a complete package of code before you can use workflow commands like run to interact with the runner machine. This means you must include any package dependencies required to run the JavaScript code. For example, this action uses @actions/core and @actions/github packages.

Checking in your node_modules directory can cause problems. As an alternative, you can use tools such as rollup.js or @vercel/ncc to combine your code and dependencies into one file for distribution.

  1. Install rollup and its plugins by running this command in your terminal.

    npm install --save-dev rollup @rollup/plugin-commonjs @rollup/plugin-node-resolve

  2. Create a new file called rollup.config.js in the root of your repository with the following code.

    JavaScript
    import commonjs from "@rollup/plugin-commonjs";
import { nodeResolve } from "@rollup/plugin-node-resolve";

const config = {
  input: "src/index.js",
  output: {
    esModule: true,
    file: "dist/index.js",
    format: "es",
    sourcemap: true,
  },
  plugins: [commonjs(), nodeResolve({ preferBuiltins: true })],
};

export default config;

  3. Compile your dist/index.js file.

    rollup --config rollup.config.js

    You'll see a new dist/index.js file with your code and any dependencies.

  4. From your terminal, commit the updates.

    Shell
    git add src/index.js dist/index.js rollup.config.js package.json package-lock.json README.md action.yml
git commit -m "Initial commit of my first action"
git tag -a -m "My first action release" v1.1
git push --follow-tags

When you commit and push your code, your updated repository should look like this:

hello-world-javascript-action/
├── action.yml
├── dist/
│   └── index.js
├── package.json
├── package-lock.json
├── README.md
├── rollup.config.js
└── src/
    └── index.js

Testing out your action in a workflow

Now you're ready to test your action out in a workflow.

Public actions can be used by workflows in any repository. When an action is in a private repository, the repository settings dictate whether the action is available only within the same repository or also to other repositories owned by the same user or organization. For more information, see 리포지토리에 대한 GitHub Actions 설정 관리.

Example using a public action

This example demonstrates how your new public action can be run from within an external repository.

Copy the following YAML into a new file at .github/workflows/main.yml, and update the uses: octocat/hello-world-javascript-action@1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b line with your username and the name of the public repository you created above. You can also replace the who-to-greet input with your name.

YAML
on:
  push:
    branches:
      - main

jobs:
  hello_world_job:
    name: A job to say hello
    runs-on: ubuntu-latest

    steps:
      - name: Hello world action step
        id: hello
        uses: octocat/hello-world-javascript-action@1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b
        with:
          who-to-greet: Mona the Octocat

      # Use the output from the `hello` step
      - name: Get the output time
        run: echo "The time was ${{ steps.hello.outputs.time }}"

When this workflow is triggered, the runner will download the hello-world-javascript-action action from your public repository and then execute it.

Example using a private action

Copy the workflow code into a .github/workflows/main.yml file in your action's repository. You can also replace the who-to-greet input with your name.

YAML
on:
  push:
    branches:
      - main

jobs:
  hello_world_job:
    name: A job to say hello
    runs-on: ubuntu-latest

    steps:
      # To use this repository's private action,
      # you must check out the repository
      - name: Checkout
        uses: actions/checkout@v4

      - name: Hello world action step
        uses: ./ # Uses an action in the root directory
        id: hello
        with:
          who-to-greet: Mona the Octocat

      # Use the output from the `hello` step
      - name: Get the output time
        run: echo "The time was ${{ steps.hello.outputs.time }}"

리포지토리에서 작업 탭을 클릭하고 최신 워크플로 실행을 선택합니다. 작업 아래 또는 시각화 그래프에서 인사할 작업을 클릭합니다.

Hello world 동작 단계 클릭하면 “Hello Mona Octocat” 또는 who-to-greet 입력에 사용한 이름이 로그에 표시되어야 합니다.. 타임스탬프를 보려면 출력 시간 가져오기를 클릭합니다.

Template repositories for creating JavaScript actions

GitHub provides template repositories for creating JavaScript and TypeScript actions. You can use these templates to quickly get started with creating a new action that includes tests, linting, and other recommended practices.

Example JavaScript actions on GitHub.com

You can find many examples of JavaScript actions on GitHub.com.