# Routing

The GitLab backend is written primarily with Rails so it uses [Rails
routing](https://guides.rubyonrails.org/routing.html). Beside Rails best
practices, there are few rules unique to the GitLab application. To
support subgroups, GitLab project and group routes use the wildcard
character to match project and group routes. For example, we might have
a path such as:

    /gitlab-com/customer-success/north-america/west/customerA

However, paths can be ambiguous. Consider the following example:

    /gitlab-com/edit

It's ambiguous whether there is a subgroup named `edit` or whether
this is a special endpoint to edit the `gitlab-com` group.

To eliminate the ambiguity and to make the backend easier to maintain,
we introduced the `/-/` scope. The purpose of it is to separate group or
project paths from the rest of the routes. Also it helps to reduce the
number of [reserved names](../user/reserved_names.md).

## Global routes

We have a number of global routes. For example:

    /-/health
    /-/metrics

## Group routes

Every group route must be under the `/-/` scope.

Examples:

    gitlab-org/-/edit
    gitlab-org/-/activity
    gitlab-org/-/security/dashboard
    gitlab-org/serverless/-/activity

To achieve that, use the `scope '-'` method.

## Project routes

Every project route must be under the `/-/` scope, except cases where a Git
client or other software requires something different.

Examples:

    gitlab-org/gitlab-ce/-/activity
    gitlab-org/gitlab-ce/-/jobs/123
    gitlab-org/gitlab-ce/-/settings/repository
    gitlab-org/serverless/runtimes/-/settings/repository

Currently, only some project routes are placed under the `/-/` scope. However,
you can help us migrate more of them! To migrate project routes:

1. Modify existing routes by adding `-` scope.
1. Add redirects for legacy routes by using `Gitlab::Routing.redirect_legacy_paths`.
1. Create a technical debt issue to remove deprecated routes in later releases.

To get started, see an [example merge request](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28435).
