CodePipeline self-managed Gitlab does not list all repositories

The issue you're experiencing with AWS CodePipeline not listing all repositories from your self-managed GitLab instance is likely related to the permissions associated with your GitLab personal access token (PAT).

When setting up a connection between CodePipeline and a self-managed GitLab instance, the PAT you use determines which repositories are accessible. If you're only seeing your personal projects, it suggests that the token doesn't have the necessary permissions to access group or organizational projects.

To resolve this issue:

1. Create a new personal access token in GitLab with broader permissions. Ensure that it has the 'api' scope, which allows access to the GitLab API.

2. If the project is part of a group or organization, make sure the token is associated with an account that has the appropriate access rights to that group or project.

3. In CodePipeline, update the connection with the new token that has the correct permissions.

4. If you're entering a group/project name manually and getting a 404 error, double-check the exact path and ensure it matches the GitLab project structure (e.g., group/subgroup/project).

5. Verify that the GitLab user associated with the token has at least "Reporter" access to the project you're trying to access, as this is the minimum required for read access to repositories.

If after trying these steps you still encounter issues, it may be worth checking with your GitLab administrators to ensure there are no additional access controls or restrictions in place that could be preventing CodePipeline from listing or accessing certain repositories.
Sources
Adding Gitlab self-managed host to codepipline URL can't begin with "https://gitlab.com", e.g. "https://gitlab.compare.com" | AWS re:Post
Connections for GitLab self-managed - AWS CodePipeline