Add filepath redirect url

Part of https://gitlab.com/gitlab-org/gitlab/issues/27300

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/25541

app/controllers/projects/releases_controller.rb

@@ -3,7 +3,7 @@
 class Projects::ReleasesController < Projects::ApplicationController
   # Authorize
   before_action :require_non_empty_project, except: [:index]
-  before_action :release, only: %i[edit show update]
+  before_action :release, only: %i[edit show update downloads]
   before_action :authorize_read_release!
   before_action do
     push_frontend_feature_flag(:release_issue_summary, project)
@@ -40,6 +40,10 @@ class Projects::ReleasesController < Projects::ApplicationController
     end
   end
 
+  def downloads
+    redirect_to link.url
+  end
+
   protected
 
   def releases
@@ -69,6 +73,14 @@ class Projects::ReleasesController < Projects::ApplicationController
     @release ||= project.releases.find_by_tag!(sanitized_tag_name)
   end
 
+  def link
+    release.links.find_by_filepath!(sanitized_filepath)
+  end
+
+  def sanitized_filepath
+    CGI.unescape(params[:filepath])
+  end
+
   def sanitized_tag_name
     CGI.unescape(params[:tag])
   end

changelogs/unreleased/27300-add-filepath-redirect-url.yml

+---
+title: Add filepath redirect url
+merge_request: 25541
+author:
+type: added

config/routes/project.rb

@@ -171,6 +171,7 @@ constraints(::Constraints::ProjectUrlConstrainer.new) do
         resources :releases, only: [:index, :show, :edit], param: :tag, constraints: { tag: %r{[^/]+} } do
           member do
             get :evidence
+            get :downloads, path: 'downloads/*filepath', format: false
           end
         end
 

spec/controllers/projects/releases_controller_spec.rb

@@ -198,6 +198,63 @@ describe Projects::ReleasesController do
     end
   end
 
+  context 'GET #downloads' do
+    subject do
+      get :downloads, params: {
+        namespace_id: project.namespace,
+        project_id: project,
+        tag: tag,
+        filepath: filepath
+       }
+    end
+
+    before do
+      sign_in(user)
+    end
+
+    let(:release) { create(:release, project: project, tag: tag ) }
+    let(:tag) { 'v11.9.0-rc2' }
+    let(:db_filepath) { '/binaries/linux-amd64' }
+    let!(:link) do
+      create :release_link,
+        release: release,
+        name: 'linux-amd64 binaries',
+        filepath: db_filepath,
+        url: 'https://downloads.example.com/bin/gitlab-linux-amd64'
+    end
+
+    context 'valid filepath' do
+      let(:filepath) { CGI.escape('/binaries/linux-amd64') }
+
+      it 'redirects to the asset direct link' do
+        subject
+
+        expect(response).to redirect_to(link.url)
+      end
+    end
+
+    context 'invalid filepath' do
+      let(:filepath) { CGI.escape('/binaries/win32') }
+
+      it 'is not found' do
+        subject
+
+        expect(response).to have_gitlab_http_status(:not_found)
+      end
+    end
+
+    context 'ignores filepath extension' do
+      let(:db_filepath) { '/binaries/linux-amd64.json' }
+      let(:filepath) { CGI.escape(db_filepath) }
+
+      it 'redirects to the asset direct link' do
+        subject
+
+        expect(response).to redirect_to(link.url)
+      end
+    end
+  end
+
   describe 'GET #evidence' do
     let_it_be(:tag_name) { "v1.1.0-evidence" }
     let!(:release) { create(:release, :with_evidence, project: project, tag: tag_name) }