Explicitly require format.json in prometheus_controller

+ add missing prometheus_controller tests!

2 files changed, 16 insertions, 7 deletions

diff --git a/app/controllers/projects/deployments_controller.rb b/app/controllers/projects/deployments_controller.rb
index 29d94e2760a..acf5573935a 100644
--- a/app/controllers/projects/deployments_controller.rb
+++ b/app/controllers/projects/deployments_controller.rb
@@ -24,10 +24,11 @@ class Projects::DeploymentsController < Projects::ApplicationController
 
   def additional_metrics
     return render_404 unless deployment.has_additional_metrics?
+
     metrics = deployment.additional_metrics
 
-    if metrics&.any?
-      render json: metrics, status: :ok
+    if metrics.any?
+      render json: metrics
     else
       head :no_content
     end
diff --git a/app/controllers/projects/prometheus_controller.rb b/app/controllers/projects/prometheus_controller.rb
index 0402be6f85c..4a39d13881e 100644
--- a/app/controllers/projects/prometheus_controller.rb
+++ b/app/controllers/projects/prometheus_controller.rb
@@ -3,17 +3,25 @@ class Projects::PrometheusController < Projects::ApplicationController
   before_action :require_prometheus_metrics!
 
   def active_metrics
-    matched_metrics = prometheus_service.reactive_query(Gitlab::Prometheus::Queries::MatchedMetricsQuery.name, &:itself)
+    matched_metrics = prometheus_service.reactive_query(Gitlab::Prometheus::Queries::MatchedMetricsQuery.name, &:itself) || {}
 
-    if matched_metrics
-      render json: matched_metrics, status: :ok
-    else
-      head :no_content
+    respond_to do |format|
+      format.json do
+        if matched_metrics.any?
+          render json: matched_metrics
+        else
+          head :no_content
+        end
+      end
     end
   end
 
   private
 
+  rescue_from(ActionController::UnknownFormat) do |e|
+    render_404
+  end
+
   def prometheus_service
     project.monitoring_service
   end