Interacting with GitHub

Probot uses GitHub Apps. An app is a first-class actor on GitHub, like a user (e.g. @defunkt) or an organization (e.g. @github). The app is given access to a repository or repositories by being “installed” on a user or organization account and can perform actions through the API like commenting on an issue or creating a status.

Your app has access to an authenticated GitHub client that can be used to make API calls. It supports both the GitHub REST API, and the GitHub GraphQL API.

REST API

context.github is an instance of the @octokit/rest Node.js module, which wraps the GitHub REST API and allows you to do almost anything programmatically that you can do through a web browser.

Here is an example of an autoresponder app that comments on opened issues:

module.exports = app => {
  app.on('issues.opened', async context => {
    // `context` extracts information from the event, which can be passed to
    // GitHub API calls. This will return:
    //   { owner: 'yourname', repo: 'yourrepo', number: 123, body: 'Hello World! }
    const params = context.issue({ body: 'Hello World!' })

    // Post a comment on the issue
    return context.github.issues.createComment(params)
  })
}

See the full API docs to see all the ways you can interact with GitHub. Some API endpoints are not available on GitHub Apps yet, so check which ones are available first.

GraphQL API

Use context.github.graphql to make requests to the GitHub GraphQL API.

Here is an example of the same autoresponder app from above that comments on opened issues, but this time with GraphQL:

// GraphQL query to add a comment
const addComment = `
  mutation comment($id: ID!, $body: String!) {
    addComment(input: {subjectId: $id, body: $body}) {
      clientMutationId
    }
  }
`

module.exports = app => {
  app.on('issues.opened', async context => {
    // Post a comment on the issue
    context.github.graphql(addComment, {
      id: context.payload.issue.node_id,
      body: 'Hello World'
    })
  })
}

The options in the 2nd argument will be passed as variables to the query. You can pass custom headers by using the headers key:

// GraphQL query to pin an issue
const pinIssue = `
  mutation comment($id: ID!) {
    pinIssue(input: {subjectId: $id}) {
      clientMutationId
    }
  }
`

module.exports = app => {
  app.on('issues.opened', async context => {
    context.github.graphql(pinIssue, {
      id: context.payload.issue.node_id,
      headers: {
        accept: 'application/vnd.github.elektra-preview+json'
      }
    })
  })
}

Check out the GitHub GraphQL API docs to learn more.

Unauthenticated Events

When receiving webhook events, context.github is usually an authenticated client, but there are a few events that are exceptions:

• installation.deleted - The installation was just deleted, so we can’t authenticate as the installation.

• marketplace_purchase - The purchase happens before the app is installed on an account.

For these events, context.github will be authenticated as the GitHub App instead of as a specific installation.

GitHub Enterprise

If you want to run a Probot App against a GitHub Enterprise instance, you’ll need to create and set the GHE_HOST environment variable inside of the .env file.

GHE_HOST=fake.github-enterprise.com

GitHub Apps are enabled in GitHub Enterprise 2.12 as an early access technical preview but are generally available in GitHub Enterprise 2.13 and above.