Add ability to resolve project id into path

By visiting `projects/:id` you will be redirected to project page with
path in it.

projects/123 => foo/bar
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/controllers/projects_controller.rb

@@ -10,10 +10,10 @@ class ProjectsController < Projects::ApplicationController
   prepend_before_action(only: [:show]) { authenticate_sessionless_user!(:rss) }
 
   before_action :whitelist_query_limiting, only: [:create]
-  before_action :authenticate_user!, except: [:index, :show, :activity, :refs]
+  before_action :authenticate_user!, except: [:index, :show, :activity, :refs, :resolve]
   before_action :redirect_git_extension, only: [:show]
-  before_action :project, except: [:index, :new, :create]
-  before_action :repository, except: [:index, :new, :create]
+  before_action :project, except: [:index, :new, :create, :resolve]
+  before_action :repository, except: [:index, :new, :create, :resolve]
   before_action :assign_ref_vars, only: [:show], if: :repo_exists?
   before_action :tree, only: [:show], if: [:repo_exists?, :project_view_files?]
   before_action :lfs_blob_ids, only: [:show], if: [:repo_exists?, :project_view_files?]
@@ -442,4 +442,14 @@ class ProjectsController < Projects::ApplicationController
   def present_project
     @project = @project.present(current_user: current_user)
   end
+
+  def resolve
+    @project = Project.find(params[:id])
+
+    if can?(current_user, :read_project, @project)
+      redirect_to @project
+    else
+      render_404
+    end
+  end
 end

changelogs/unreleased/53671-redirect-projects-id-to-project-page.yml

+---
+title: Redirect GET projects/:id to project page
+merge_request: 24467
+author:
+type: added

config/routes/project.rb

@@ -2,6 +2,8 @@ resources :projects, only: [:index, :new, :create]
 
 draw :git_http
 
+get '/projects/:id' => 'projects#resolve'
+
 constraints(::Constraints::ProjectUrlConstrainer.new) do
   # If the route has a wildcard segment, the segment has a regex constraint,
   # the segment is potentially followed by _another_ wildcard segment, and

doc/user/project/index.md

@@ -163,3 +163,10 @@ machine example.gitlab.com
 login <gitlab_user_name>
 password <personal_access_token>
 ```
+
+## Access project page with project ID
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/53671) in GitLab 11.8.
+
+To quickly access a project from the GitLab UI using the project ID,
+visit the `/projects/:id` URL in your browser or other tool accessing the project.

spec/controllers/projects_controller_spec.rb

@@ -955,6 +955,59 @@ describe ProjectsController do
     end
   end
 
+  describe 'GET resolve' do
+    shared_examples 'resolvable endpoint' do
+      it 'redirects to the project page' do
+        get :resolve, params: { id: project.id }
+
+        expect(response).to have_gitlab_http_status(302)
+        expect(response).to redirect_to(project_path(project))
+      end
+    end
+
+    context 'with an authenticated user' do
+      before do
+        sign_in(user)
+      end
+
+      context 'when user has access to the project' do
+        before do
+          project.add_developer(user)
+        end
+
+        it_behaves_like 'resolvable endpoint'
+      end
+
+      context 'when user has no access to the project' do
+        it 'gives 404 for existing project' do
+          get :resolve, params: { id: project.id }
+
+          expect(response).to have_gitlab_http_status(404)
+        end
+      end
+
+      it 'gives 404 for non-existing project' do
+        get :resolve, params: { id: '0' }
+
+        expect(response).to have_gitlab_http_status(404)
+      end
+    end
+
+    context 'non authenticated user' do
+      context 'with a public project' do
+        let(:project) { public_project }
+
+        it_behaves_like 'resolvable endpoint'
+      end
+
+      it 'gives 404 for private project' do
+        get :resolve, params: { id: project.id }
+
+        expect(response).to have_gitlab_http_status(404)
+      end
+    end
+  end
+
   def project_moved_message(redirect_route, project)
     "Project '#{redirect_route.path}' was moved to '#{project.full_path}'. Please update any links and bookmarks that may still have the old path."
   end

spec/routing/project_routing_spec.rb

@@ -122,6 +122,10 @@ describe 'project routing' do
         route_to('projects#preview_markdown', namespace_id: 'gitlab', id: 'gitlabhq')
       )
     end
+
+    it 'to #resolve' do
+      expect(get('/projects/1')).to route_to('projects#resolve', id: '1')
+    end
   end
 
   # members_namespace_project_autocomplete_sources_path        GET /:project_id/autocomplete_sources/members(.:format)        projects/autocomplete_sources#members