info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
1. See [Initial OmniAuth Configuration](../../integration/omniauth.md#initial-omniauth-configuration) for initial settings to enable single sign-on and add `atlassian_oauth2` as an OAuth provider.
1. Change `YOUR_CLIENT_ID` and `YOUR_CLIENT_SECRET` to the Client credentials you received in [application registration](#atlassian-application-registration) steps.
1. Save the configuration file.
1. [Reconfigure](../restart_gitlab.md#omnibus-gitlab-reconfigure) or [restart GitLab](../restart_gitlab.md#installations-from-source) 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 an Atlassian icon below the regular sign in form. Click the icon to begin the authentication process.
If everything goes right, the user is signed in to GitLab using their Atlassian credentials.