Introduce Projects::ArtifactsController#search:

So we redirect from ref and build_name to the particular build, namely:

* /u/r/artifacts/ref/build_name/* -> /u/r/builds/:build_id/artifacts/*

For:

* download
* browse
* file

app/controllers/projects/artifacts_controller.rb

@@ -35,14 +35,34 @@ class Projects::ArtifactsController < Projects::ApplicationController
     redirect_to namespace_project_build_path(project.namespace, project, build)
   end
 
+  def search
+    url = namespace_project_build_url(project.namespace, project, build)
+
+    if params[:path]
+      redirect_to "#{url}/artifacts/#{params[:path]}"
+    else
+      render_404
+    end
+  end
+
   private
 
   def validate_artifacts!
-    render_404 unless build.artifacts?
+    render_404 unless build && build.artifacts?
   end
 
   def build
-    @build ||= project.builds.find_by!(id: params[:build_id])
+    @build ||= build_from_id || build_from_ref
+  end
+
+  def build_from_id
+    project.builds.find_by(id: params[:build_id]) if params[:build_id]
+  end
+
+  def build_from_ref
+    if params[:ref]
+      project.builds_for(params[:build_name], params[:ref]).latest.first
+    end
   end
 
   def artifacts_file

config/routes.rb

@@ -733,6 +733,12 @@ Rails.application.routes.draw do
 
         resources :environments, only: [:index, :show, :new, :create, :destroy]
 
+        resources :artifacts, only: [] do
+          collection do
+            get :search, path: ':ref/:build_name(/*path)', format: false
+          end
+        end
+
         resources :builds, only: [:index, :show], constraints: { id: /\d+/ } do
           collection do
             post :cancel_all