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Google OAuth 2.0 OmniAuth Provider (FREE SELF)

To enable the Google OAuth 2.0 OmniAuth provider you must register your application with Google. Google generates a client ID and secret key for you to use.

Enable Google OAuth

In Google's side:

  1. Navigate to the cloud resource manager page

  2. Select Create Project

  3. Provide the project information:

    • Project name - "GitLab" works just fine here.
    • 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.

  4. Refresh the page and you should see your new project in the list

  5. Go to the Google API Console

  6. In the upper-left corner, select the previously created project

  7. Select Credentials from the sidebar

  8. Select OAuth consent screen and fill the form with the required information

  9. In the Credentials tab, select Create credentials > OAuth client ID

  10. Fill in the required information

    • Application type - Choose "Web Application"

    • Name - Use the default one or provide your own

    • Authorized JavaScript origins -This isn't really used by GitLab but go ahead and put https://gitlab.example.com

    • 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

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

  12. To enable projects to access Google Kubernetes Engine, you must also enable these APIs:

    • Google Kubernetes Engine API
    • Cloud Resource Manager API
    • Cloud Billing API

    To do so you should:

    1. Go to the Google API Console.
    2. Select ENABLE APIS AND SERVICES at the top of the page.
    3. Find each of the above APIs. On the page for the API, select ENABLE. 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:

    sudo editor /etc/gitlab/gitlab.rb

    For installations from source:

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

  2. Configure the common settings to add google_oauth2 as a single sign-on provider. This enables Just-In-Time account provisioning for users who do not have an existing GitLab account.

  3. Add the provider configuration:

    For Omnibus GitLab:

    gitlab_rails['omniauth_providers'] = [
  {
    name: "google_oauth2",
    # label: "Provider name", # optional label for login button, defaults to "Google"
    app_id: "YOUR_APP_ID",
    app_secret: "YOUR_APP_SECRET",
    args: { access_type: "offline", approval_prompt: "" }
  }
]

    For installations from source:

    - { name: 'google_oauth2',
    # label: 'Provider name', # optional label for login button, defaults to "Google"
    app_id: 'YOUR_APP_ID',
    app_secret: 'YOUR_APP_SECRET',
    args: { access_type: 'offline', approval_prompt: '' } }

  4. Change YOUR_APP_ID to the client ID from the Google Developer page

  5. Similarly, change YOUR_APP_SECRET to the client secret

  6. Make sure that you configure GitLab to use a fully-qualified domain name, as Google doesn't accept raw IP addresses.

    For Omnibus packages:

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

    For installations from source:

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

  7. Save the configuration file.

  8. For the changes to take effect:

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