Added GitLab configuration

Author: danciaclara

images/integrations/gitlab/add-app-details.webp

@@ -94,7 +94,8 @@
           "group": "Integrations",
           "pages": [
               "self-hosting/govern/integrations/github",
-              "self-hosting/govern/integrations/slack"
+              "self-hosting/govern/integrations/slack",
+              "self-hosting/govern/integrations/gitlab"
             ]
         },
         "self-hosting/govern/reverse-proxy",

images/integrations/gitlab/add-gitlab-application.webp

@@ -0,0 +1,61 @@
+---
+title : Configure GitLab Application for Plane integration
+sidebarTitle: GitLab
+---
+
+This guide walks you through setting up a GitLab application to enable GitLab integration for your Plane workspace on a self-hosted instance. Since self-hosted environments don’t come pre-configured for GitLab, you’ll need to create an application, configure authentication, and set the necessary permissions to ensure seamless integration.
+
+In this guide, you’ll:
+
+1. [Create and configure a GitLab Application](/self-hosting/govern/integrations/gitlab#create-a-gitlab-application)
+2. [Configure your Plane instance](/self-hosting/govern/integrations/gitlab#configure-plane-instance)
+
+## Create GitLab Application
+
+1. On the left sidebar in GitLab, select your avatar.
+
+2. Select **Preferences**.
+
+3. Navigate to the **Applications** tab.
+
+4. Click on **Add new application** to begin the setup.
+    ![Add GitLab application](/images/integrations/gitlab/add-gitlab-application.webp)
+
+5. Provide a **Name** for your application.
+
+6. Enter the following **Redirect URI**, replacing [YOUR_DOMAIN] with your actual domain:
+    ```bash
+    https://[YOUR_DOMAIN]/silo/api/gitlab/auth/callback
+    ```
+7. You can choose to check or leave the **Confidential** box unchecked—both options work for Plane.
+
+    ![Add app details](/images/integrations/gitlab/add-app-details.webp)
+
+8. Set permissions by selecting the required **Scopes**. The table below explains each scope:
+
+    |Permission|Explanation|
+    |----------|-----------|
+    |`api`|Grants full read/write access to the API, including all groups, projects, container registry, dependency proxy, and package registry. Required for API requests.|
+    |`read_api`|Allows read-only access to all groups, projects, container registry, and package registry.|
+    |`read_user`|Grants read-only access to user profiles via the /user API endpoint, including username, public email, and full name. Also provides access to /users endpoints.|
+    |`read_repository`|Enables read-only access to repositories in private projects via Git-over-HTTP or the Repository Files API.|
+    |`write_repository`|Allows read/write access to repositories on private projects via Git-over-HTTP (not through the API).|
+    |`profile`|Grants read-only access to the user's profile data using OpenID Connect.|
+    |`email`|Provides read-only access to the user's primary email address using OpenID Connect.|
+
+9. Click **Save Application** to finalize the setup.
+
+## Configure Plane instance
+
+1. Copy the **Application ID** and **Secret** from the newly created application.
+    ![Copy credentials](/images/integrations/gitlab/copy-credentials.webp)
+
+2. Add these environment variables with the values to your Plane instance's `.env` file. 
+
+    ```bash
+    GITLAB_CLIENT_ID=<application_id>
+    GITLAB_CLIENT_SECRET=<secret>
+    ```
+3. Save the file and restart the instance. 
+
+4. Once you've completed the instance configuration, [activate the GitLab integration in Plane](https://docs.plane.so/integrations/gitlab).