Merge branch '63044-add-prom-proxies-ce' into 'master'

Add method to authorize reading from prometheus proxy

Closes #63044

See merge request gitlab-org/gitlab-ce!32305

Author: ayufan

app/controllers/clusters/base_controller.rb

@@ -31,6 +31,10 @@ def authorize_create_cluster!
     access_denied! unless can?(current_user, :create_cluster, clusterable)
   end
 
+  def authorize_read_prometheus!
+    access_denied! unless can?(current_user, :read_prometheus, clusterable)
+  end
+
   def clusterable
     raise NotImplementedError
   end

app/policies/clusters/instance_policy.rb

@@ -8,6 +8,7 @@ class InstancePolicy < BasePolicy
       enable :create_cluster
       enable :update_cluster
       enable :admin_cluster
+      enable :read_prometheus
     end
   end
 end