GitHub Authentication Provider

The Backstage core-plugin-api package comes with a GitHub authentication provider that can authenticate users using GitHub or GitHub Enterprise OAuth.

Create an OAuth App on GitHub

To add GitHub authentication, you must create either a GitHub App or an OAuth App from the GitHub developer settings. The Homepage URL should point to Backstage's frontend, while the Authorization callback URL will point to the auth backend.

Note that if you're using a GitHub App, the allowed scopes are configured as part of that app. This means you need to verify what scopes the plugins you use require, so be sure to check the plugin READMEs for that information.

Settings for local development:

• Application name: Backstage (or your custom app name)
• Homepage URL: http://localhost:3000
• Authorization callback URL: http://localhost:7007/api/auth/github/handler/frame

Difference between GitHub Apps and GitHub OAuth Apps

GitHub Apps handle OAuth scope at the app installation level, meaning that the scope parameter for the call to getAccessToken in the frontend has no effect. When calling getAccessToken in open source plugins, one should still include the appropriate scope, but also document in the plugin README what scopes are required for GitHub Apps.

Configuration

The provider configuration can then be added to your app-config.yaml under the root auth configuration:

auth:
  environment: development
  providers:
    github:
      development:
        clientId: ${AUTH_GITHUB_CLIENT_ID}
        clientSecret: ${AUTH_GITHUB_CLIENT_SECRET}
        ## uncomment if using GitHub Enterprise
        # enterpriseInstanceUrl: ${AUTH_GITHUB_ENTERPRISE_INSTANCE_URL}
        ## uncomment to set lifespan of user session
        # sessionDuration: { hours: 24 } # supports `ms` library format (e.g. '24h', '2 days'), ISO duration, "human duration" as used in code
        signIn:
          resolvers:
            # See https://backstage.io/docs/auth/github/provider#resolvers for more resolvers
            - resolver: userIdMatchingUserEntityAnnotation

The GitHub provider is a structure with these configuration keys:

• clientId: The client ID that you generated on GitHub, e.g., b59241722e3c3b4816e2
• clientSecret: The client secret tied to the generated client ID.
• enterpriseInstanceUrl (optional): The base URL for a GitHub Enterprise instance, e.g., https://ghe.<company>.com. Only needed for GitHub Enterprise.
• callbackUrl (optional): The callback URL that GitHub will use when initiating an OAuth flow, e.g., https://your-intermediate-service.com/handler. Only needed if Backstage is not the immediate receiver (e.g., one OAuth app for many backstage instances).
• sessionDuration (optional): Lifespan of the user session.
• signIn: The configuration for the sign-in process, including the resolvers that should be used to match the user from the auth provider with the user entity in the Backstage catalog (typically a single resolver is sufficient).

Resolvers

This provider includes several resolvers out of the box that you can use:

• emailMatchingUserEntityProfileEmail: Matches the email address from the auth provider with the User entity that has a matching spec.profile.email. If no match is found, it will throw a NotFoundError.
• emailLocalPartMatchingUserEntityName: Matches the local part of the email address from the auth provider with the User entity that has a matching name. If no match is found, it will throw a NotFoundError.
• userIdMatchingUserEntityAnnotation: Matches the GitHub user ID with the User entity that has a matching github.com/user-id annotation. If no match is found, it will throw a NotFoundError.
• usernameMatchingUserEntityName (deprecated): Matches the username from the auth provider with the User entity that has a matching name. If no match is found, it will throw a NotFoundError.

caution

GitHub usernames can change and become available to other users. Prefer userIdMatchingUserEntityAnnotation, which uses the immutable GitHub user ID.

note

The resolvers will be tried in order but will only be skipped if they throw a NotFoundError.

If these resolvers do not fit your needs, you can build a custom resolver; this is covered in the Building Custom Resolvers section of the Sign-in Identities and Resolvers documentation.

Backend Installation

To add the provider to the backend we will first need to install the package by running this command:

from your Backstage root directory

yarn --cwd packages/backend add @backstage/plugin-auth-backend-module-github-provider

Then we will need to add this line:

in packages/backend/src/index.ts

backend.add(import('@backstage/plugin-auth-backend'));
backend.add(import('@backstage/plugin-auth-backend-module-github-provider'));

Adding the provider to the Backstage frontend

To add the provider to the frontend, add the githubAuthApi reference and SignInPage component as shown in Adding the provider to the sign-in page.