Merge pull request #351 from abstractj/KEYCLOAK-5818

KEYCLOAK-5818] Create documentation for GitLab social IdP

server_admin/topics.adoc

@@ -73,6 +73,7 @@ include::topics/identity-broker/social/microsoft.adoc[]
 include::topics/identity-broker/social/paypal.adoc[]
 include::topics/identity-broker/social/stack-overflow.adoc[]
 include::topics/identity-broker/social/openshift.adoc[]
+include::topics/identity-broker/social/gitlab.adoc[]
 include::topics/identity-broker/oidc.adoc[]
 include::topics/identity-broker/saml.adoc[]
 include::topics/identity-broker/suggested.adoc[]

server_admin/topics/identity-broker/social/gitlab.adoc

@@ -0,0 +1,29 @@
+==== GitLab
+
+There are a number of steps you have to complete to be able to login to GitLab.
+
+First, go to the `Identity Providers` left menu item and select `GitLab` from the `Add provider` drop down list. This will bring you to the `Add identity provider` page.
+
+.Add Identity Provider
+image:{project_images}/gitlab-add-identity-provider.png[]
+
+Before you can click `Save`, you must obtain a `Client ID` and `Client Secret` from GitLab.
+
+NOTE: You will the `Redirect URI` from this page in a later step, which you will provide to GitLab when you register {project_name} as a client there.
+
+To enable login with GitLab you first have to register an application project in
+https://docs.gitlab.com/ee/integration/oauth_provider.html[GitLab as OAuth2 authentication service provider].
+
+NOTE: GitLab often changes the look and feel of application registration, so what you see on the GitLab site may differ. If in doubt, see the GitLab documentation.
+
+.Add a New App
+image:images/gitlab-developer-applications.png[]
+
+Copy the `Redirect URI` from the {project_name} `Add Identity Provider` page and enter it into the `Authorization callback URL` field on the GitLab `Register a new OAuth application` page.
+
+.GitLab App Page
+image:images/gitlab-app-page.png[]
+
+When you are done registering, click `Save application`. This will open the application management page in GitLab. Find the client ID and secret from this page so you can enter them into the {project_name} `Add identity provider` page.
+
+To finish, return to {project_name} and enter them. Click `Save`.