Merge branch 'pl-env-metrics-json' into 'master'

Load environment metrics only for JSON endpoint

See merge request gitlab-org/gitlab-ce!27743

app/controllers/projects/environments_controller.rb

@@ -135,13 +135,13 @@ class Projects::EnvironmentsController < Projects::ApplicationController
   end
 
   def metrics
-    # Currently, this acts as a hint to load the metrics details into the cache
-    # if they aren't there already
-    @metrics = environment.metrics || {}
-
     respond_to do |format|
       format.html
       format.json do
+        # Currently, this acts as a hint to load the metrics details into the cache
+        # if they aren't there already
+        @metrics = environment.metrics || {}
+
         render json: @metrics, status: @metrics.any? ? :ok : :no_content
       end
     end

spec/controllers/projects/environments_controller_spec.rb

@@ -342,11 +342,9 @@ describe Projects::EnvironmentsController do
     end
 
     context 'when environment has no metrics' do
-      before do
-        expect(environment).to receive(:metrics).and_return(nil)
-      end
-
       it 'returns a metrics page' do
+        expect(environment).not_to receive(:metrics)
+
         get :metrics, params: environment_params
 
         expect(response).to be_ok
@@ -354,6 +352,8 @@ describe Projects::EnvironmentsController do
 
       context 'when requesting metrics as JSON' do
         it 'returns a metrics JSON document' do
+          expect(environment).to receive(:metrics).and_return(nil)
+
           get :metrics, params: environment_params(format: :json)
 
           expect(response).to have_gitlab_http_status(204)