What are GitLab project settings and how do you configure protected branches and merge request approvals?

Think of project settings like the security system and house rules for a shared apartment building. Protected branches are like the locks on the building's main entrance: only residents with the right key (permitted roles) can enter, and nobody can break down the door (force-push). Merge request approvals are like the building's renovation policy: before you can knock down a wall (merge code), you need sign-off from the building manager (lead developer) and a structural engineer (security reviewer). The settings ensure the building stays safe and livable for everyone.

GitLab project settings are accessed through the left sidebar under Settings and are organized into subsections: General (project name, visibility, features), Repository (protected branches, deploy keys, mirroring), CI/CD (runners, variables, pipeline settings), Merge Requests (approval rules, merge methods, merge checks), and more. Protected branches are configured under Settings > Repository > Protected Branches. You select a branch pattern (exact name like main or a wildcard like release-*), then specify who can push and who can merge. Options range from 'No one' (all changes must come through merge requests) to 'Maintainers' or 'Developers and Maintainers'. You can also prevent force pushes, which is critical for maintaining a clean and auditable commit history on production branches.

Internally, when a developer attempts to push directly to a protected branch, GitLab's pre-receive hook checks the user's role against the branch protection configuration. If the user does not have the required permission level, the push is rejected with an error message indicating that the branch is protected. For merge requests targeting a protected branch, GitLab evaluates the approval rules before enabling the merge button. Approval rules can be configured at the project level or at the individual merge request level. Each rule specifies a name, the number of required approvals, and optionally a list of eligible approvers (specific users or groups). GitLab tracks which users have approved and whether their approval is still valid. The 'Prevent approval by author' setting ensures that the person who wrote the code cannot approve their own merge request, enforcing the four-eyes principle.

In production environments, a typical configuration for a critical service like payment-processor would include: main branch protected with push access limited to 'No one' and merge access to 'Maintainers only', a merge request approval rule requiring two approvals from the backend-team group, a second approval rule requiring one approval from the security-team for any MR that modifies Dockerfile or dependency files, the 'Prevent approval by author' setting enabled, the 'Remove all approvals when commits are pushed' setting enabled to prevent post-approval code changes from being merged without re-review, and the merge method set to 'Merge commit with semi-linear history' for a clean main branch history. These settings together create a robust quality gate that catches problems before they reach production.

A key gotcha is not understanding the interaction between group-level and project-level settings. In GitLab Premium and Ultimate tiers, group owners can enforce settings across all projects in the group, and project maintainers cannot weaken these settings (though they can strengthen them). For example, if a group requires two approvals, a project within that group cannot reduce it to one. Another common mistake is protecting branches after the fact without realizing that existing force-push history is not retroactively corrected. Always set up branch protection before the first merge to main. Also, wildcard patterns like release-* protect all matching branches, which is useful but can accidentally protect branches you did not intend if your naming convention is not consistent.