Do not prune kind: Elasticsearch and emit metric

Author: mvallati

lib/krane/cluster_resource_discovery.rb

@@ -19,12 +19,20 @@ def crds
     end
 
     def prunable_resources(namespaced:)
-      black_list = %w(Namespace Node ControllerRevision Event)
-      fetch_resources(namespaced: namespaced).map do |resource|
+      black_list = %w(Namespace Node ControllerRevision Event Elasticsearch)
+      elasticsearch_found = false
+      result = fetch_resources(namespaced: namespaced).map do |resource|
         next unless resource["verbs"].one? { |v| v == "delete" }
+        if resource["kind"] == "Elasticsearch"
+          elasticsearch_found = true
+          next
+        end
         next if black_list.include?(resource["kind"])
         [resource["apigroup"], resource["version"], resource["kind"]].compact.join("/")
       end.compact
+
+      StatsD.client.gauge('elasticsearch_resources.count', 1, tags: @namespace_tags) if elasticsearch_found
+      result
     end
 
     def fetch_resources(namespaced: false)

test/unit/cluster_resource_discovery_test.rb

@@ -3,6 +3,7 @@
 
 class ClusterResourceDiscoveryTest < Krane::TestCase
   include ClusterResourceDiscoveryHelper
+  include StatsD::Instrument::Assertions
 
   def test_fetch_resources_failure
     crd = mocked_cluster_resource_discovery(success: false)
@@ -49,7 +50,7 @@ def test_prunable_namespaced_resources
     %w(ConfigMap CronJob Deployment).each do |expected_kind|
       assert(kinds.one? { |k| k.include?(expected_kind) })
     end
-    %w(controllerrevision event).each do |black_listed_kind|
+    %w(controllerrevision event elasticsearch).each do |black_listed_kind|
       assert_empty(kinds.select { |k| k.downcase.include?(black_listed_kind) })
     end
   end
@@ -61,4 +62,14 @@ def test_prunable_namespaced_resources_apply_group_version_kind_overrides
       assert(kinds.one? { |k| k.include?(expected_kind) })
     end
   end
+
+  def test_elasticsearch_statsd_gauge_not_emitted_when_no_elasticsearch
+    crd = mocked_cluster_resource_discovery
+    metrics = capture_statsd_calls(client: Krane::StatsD.client) do
+      crd.prunable_resources(namespaced: true)
+    end
+
+    gauge_metric = metrics.find { |m| m.name == 'Krane.elasticsearch_resources.count' && m.type == :g }
+    assert_nil(gauge_metric, "Expected elasticsearch_resources.count gauge NOT to be emitted when no Elasticsearch exists")
+  end
 end