Merge branch '46259-prometheus-integration-fails-on-kube-1-10' into 'master'

Resolve "Prometheus integration fails on k8s 1.10"

Closes #46259

See merge request gitlab-org/gitlab-ce!19082

config/initializers/kubeclient.rb

+class Kubeclient::Client
+  # We need to monkey patch this method until
+  # https://github.com/abonas/kubeclient/pull/323 is merged
+  def proxy_url(kind, name, port, namespace = '')
+    discover unless @discovered
+    entity_name_plural =
+      if %w[services pods nodes].include?(kind.to_s)
+        kind.to_s
+      else
+        @entities[kind.to_s].resource_name
+      end
+
+    ns_prefix = build_namespace_prefix(namespace)
+    rest_client["#{ns_prefix}#{entity_name_plural}/#{name}:#{port}/proxy"].url
+  end
+end

spec/models/clusters/applications/prometheus_spec.rb

@@ -79,7 +79,7 @@ describe Clusters::Applications::Prometheus do
       end
 
       it 'creates proper url' do
-        expect(subject.prometheus_client.url).to eq('http://example.com/api/v1/proxy/namespaces/gitlab-managed-apps/service/prometheus-prometheus-server:80')
+        expect(subject.prometheus_client.url).to eq('http://example.com/api/v1/namespaces/gitlab-managed-apps/service/prometheus-prometheus-server:80/proxy')
       end
 
       it 'copies options and headers from kube client to proxy client' do