Add metric for measuring PumaWorkerKiller activity

PumaWorkerKiller is used for periodically checking and killing
workers (the biggest one) if overall memory reaches specified
limit. This metric allows us to watch number of killed workers.

1 files changed, 27 insertions, 0 deletions

diff --git a/spec/lib/gitlab/cluster/puma_worker_killer_observer_spec.rb b/spec/lib/gitlab/cluster/puma_worker_killer_observer_spec.rb
new file mode 100644
index 00000000000..180520b27e7
--- /dev/null
+++ b/spec/lib/gitlab/cluster/puma_worker_killer_observer_spec.rb
@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::Cluster::PumaWorkerKillerObserver do
+  let(:counter) { Gitlab::Metrics::NullMetric.instance }
+
+  before do
+    allow(Gitlab::Metrics).to receive(:counter)
+      .with(any_args)
+      .and_return(counter)
+  end
+
+  describe '#callback' do
+    subject { described_class.new }
+
+    it 'increments timeout counter' do
+      worker = double(index: 0)
+
+      expect(counter)
+        .to receive(:increment)
+        .with({ worker: 'worker_0' })
+
+      subject.callback.call(worker)
+    end
+  end
+end