Change route and add comments

Change route from /d to /metrics. Also add comments linking to issue.

app/controllers/projects/environments_controller.rb

 # frozen_string_literal: true
 
 class Projects::EnvironmentsController < Projects::ApplicationController
+  # Metrics dashboard code is getting decoupled from environments and is being moved
+  # into app/controllers/projects/metrics_dashboard_controller.rb
+  # See https://gitlab.com/gitlab-org/gitlab/-/issues/226002 for more details.
+
   include MetricsDashboard
 
   layout 'project'

app/controllers/projects/metrics_dashboard_controller.rb

 # frozen_string_literal: true
 module Projects
   class MetricsDashboardController < Projects::ApplicationController
+    # Metrics dashboard code is in the process of being decoupled from environments
+    # and is getting moved to this controller. Some code may be duplicated from
+    # app/controllers/projects/environments_controller.rb
+    # See https://gitlab.com/gitlab-org/gitlab/-/issues/226002 for more details.
+
     before_action :authorize_metrics_dashboard!
     before_action do
       push_frontend_feature_flag(:prometheus_computed_alerts)

config/routes/project.rb

@@ -25,7 +25,7 @@ constraints(::Constraints::ProjectUrlConstrainer.new) do
       # Use this scope for all new project routes.
       scope '-' do
         get 'archive/*id', constraints: { format: Gitlab::PathRegex.archive_formats_regex, id: /.+?/ }, to: 'repositories#archive', as: 'archive'
-        get 'd(/:dashboard_path)', constraints: { dashboard_path: /.+\.yml/ },
+        get 'metrics(/:dashboard_path)', constraints: { dashboard_path: /.+\.yml/ },
           to: 'metrics_dashboard#show', as: :metrics_dashboard, format: false
 
         resources :artifacts, only: [:index, :destroy]

spec/requests/projects/metrics_dashboard_spec.rb

@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe 'metrics dashboard page' do
+RSpec.describe 'metrics dashboard page' do
   let_it_be(:project) { create(:project) }
   let_it_be(:environment) { create(:environment, project: project) }
   let_it_be(:environment2) { create(:environment, project: project) }
@@ -13,7 +13,7 @@ describe 'metrics dashboard page' do
     login_as(user)
   end
 
-  describe 'GET /:namespace/:project/-/d' do
+  describe 'GET /:namespace/:project/-/metrics' do
     it 'returns 200' do
       send_request
       expect(response).to have_gitlab_http_status(:ok)
@@ -25,7 +25,7 @@ describe 'metrics dashboard page' do
     end
   end
 
-  describe 'GET /:namespace/:project/-/d?environment=:environment.id' do
+  describe 'GET /:namespace/:project/-/metrics?environment=:environment.id' do
     it 'returns 200' do
       send_request(environment: environment2.id)
       expect(response).to have_gitlab_http_status(:ok)
@@ -44,7 +44,7 @@ describe 'metrics dashboard page' do
     end
   end
 
-  describe 'GET /:namespace/:project/-/d/:dashboard_path' do
+  describe 'GET /:namespace/:project/-/metrics/:dashboard_path' do
     let(:dashboard_path) { '.gitlab/dashboards/dashboard_path.yml' }
 
     it 'returns 200' do
@@ -58,7 +58,7 @@ describe 'metrics dashboard page' do
     end
   end
 
-  describe 'GET :/namespace/:project/-/d/:dashboard_path?environment=:environment.id' do
+  describe 'GET :/namespace/:project/-/metrics/:dashboard_path?environment=:environment.id' do
     let(:dashboard_path) { '.gitlab/dashboards/dashboard_path.yml' }
 
     it 'returns 200' do