Google OAuth2 OmniAuth Provider

To enable the Google OAuth2 OmniAuth provider you must register your application with Google. Google will generate a client ID and secret key for you to use.

Enabling Google OAuth

In Google's side:

  1. Navigate to the cloud resource manager page
  2. Select Create Project
  3. Provide the project information:
  4. Project name - "GitLab" works just fine here.
  5. Project ID - Must be unique to all Google Developer registered applications. Google provides a randomly generated Project ID by default. You can use the randomly generated ID or choose a new one.
  6. Refresh the page and you should see your new project in the list
  7. Go to the Google API Console
  8. Select the previously created project in the upper left corner
  9. Select Credentials from the sidebar
  10. Select OAuth consent screen and fill the form with the required information
  11. In the Credentials tab, select Create credentials > OAuth client ID
  12. Fill in the required information
  13. Application type - Choose "Web Application"
  14. Name - Use the default one or provide your own
  15. Authorized JavaScript origins -This isn't really used by GitLab but go ahead and put https://gitlab.example.com

  16. Authorized redirect URIs - Enter your domain name followed by the callback URIs one at a time:

    https://gitlab.example.com/users/auth/google_oauth2/callback https://gitlab.example.com/-/google_api/auth/callback

  17. You should now be able to see a Client ID and Client secret. Note them down or keep this page open as you will need them later.

  18. To enable projects to access Google Kubernetes Engine, you must also enable these APIs:
  19. Google Kubernetes Engine API
  20. Cloud Resource Manager API
  21. Cloud Billing API

To do so you need to:

  1. Go to the Google API Console.
  2. Click on ENABLE APIS AND SERVICES button at the top of the page.
  3. Find each of the above APIs. On the page for the API, press the ENABLE button. It may take a few minutes for the API to be fully functional.

On your GitLab server:

  1. Open the configuration file.

For Omnibus GitLab:

sh sudo editor /etc/gitlab/gitlab.rb

For installations from source:

sh cd /home/git/gitlab sudo -u git -H editor config/gitlab.yml

  1. See Initial OmniAuth Configuration for initial settings.
  2. Add the provider configuration:

For Omnibus GitLab:

ruby gitlab_rails['omniauth_providers'] = [ { "name" => "google_oauth2", "app_id" => "YOUR_APP_ID", "app_secret" => "YOUR_APP_SECRET", "args" => { "access_type" => "offline", "approval_prompt" => '' } } ]

For installations from source:

yaml - { name: 'google_oauth2', app_id: 'YOUR_APP_ID', app_secret: 'YOUR_APP_SECRET', args: { access_type: 'offline', approval_prompt: '' } }

  1. Change YOUR_APP_ID to the client ID from the Google Developer page
  2. Similarly, change YOUR_APP_SECRET to the client secret
  3. Make sure that you configure GitLab to use an FQDN as Google will not accept raw IP addresses.

For Omnibus packages:

ruby external_url 'https://gitlab.example.com'

For installations from source:

yaml gitlab: host: https://gitlab.example.com

  1. Save the configuration file.
  2. Reconfigure or restart GitLab for the changes to take effect if you installed GitLab via Omnibus or from source respectively.

On the sign in page there should now be a Google icon below the regular sign in form. Click the icon to begin the authentication process. Google will ask the user to sign in and authorize the GitLab application. If everything goes well the user will be returned to GitLab and will be signed in.