🔌 @probot/adapter-github-actions

Adapter to run a Probot application function in GitHub Actions

Usage

Create your Probot Application as always

// app.js
module.exports = (app) => {
  app.on("issues.opened", async (context) => {
    const params = context.issue({ body: "Hello World!" });
    await context.octokit.issues.createComment(params);
  });
};

Then in the entrypoint of your GitHub Action, require @probot/adapter-github-actions instead of probot

// index.js
const { run } = require('@probot/adapter-github-actions')
const app = require("./app");

run(app).catch((error) => {
  console.error(error);
  process.exit(1);
});

Then use index.js as your entrypoint in the action.yml file

name: "Probot app name"
description: "Probot app description."
runs:
  using: "node12"
  main: "action.js"

Important: Your external dependencies will not be installed, you have to either vendor them in by committing the contents of the node_modules folder, or compile the code to a single executable script (recommended). See GitHub's documentation

For an example Probot App that is continuously published as GitHub Action, see https://github.com/probot/example-github-action#readme

How it works

Probot is a framework for building GitHub Apps, which is different to creating GitHub Actions in many ways, but the functionality is the same:

Both get notified about events on GitHub, which you can act on. While a GitHub App gets notified about a GitHub event via a webhook request sent by GitHub, a GitHub Action can receive the event payload by reading a JSON file from the file system. We can abstract away the differences, so the same hello world example app shown above works in both environments.

Relevant differences for Probot applications:

1. You cannot authenticate as the app. The probot instance you receive is authenticated using a GitHub token. In most cases the token will be set to secrets.GITHUB_TOKEN, which is an installation access token. The provided GITHUB_TOKEN expires when the job is done or after 6 hours, whichever comes first. You do not have access to an APP_ID or PRIVATE_KEY, you cannot create new tokens or renew the provided one.
2. secrets.GITHUB_TOKEN is scoped to the current repository. You cannot read data from other repositories unless they are public, you cannot update any other repositories, or access organization-level APIs.
3. You could provide a personal access token instead of secrets.GITHUB_TOKEN to workaround the limits of a repository-scoped token, but be sure you know what you are doing.
4. You don't need to configure WEBHOOK_SECRET, because no webhook request gets sent, the event information can directly be retrieved from environment variables and the local file system.

For a more thorough comparison, see @jasonetco's posts:

1. Probot App or GitHub Action (Jan 2019)
2. Update from April 2020

License

ISC