Merge branch 'pawel/reduce_cardinality_of_prometheus_metrics' into 'master'

Reduce cardinality of some of GitLab's Prometheus metrics and fix observed duration reporting.

Closes #41045

See merge request gitlab-org/gitlab-ce!15881

2 files changed, 11 insertions, 8 deletions

diff --git a/spec/lib/gitlab/metrics/method_call_spec.rb b/spec/lib/gitlab/metrics/method_call_spec.rb
index 78767d06462..41a9d1d9c90 100644
--- a/spec/lib/gitlab/metrics/method_call_spec.rb
+++ b/spec/lib/gitlab/metrics/method_call_spec.rb
@@ -96,14 +96,17 @@ describe Gitlab::Metrics::MethodCall do
 
   describe '#to_metric' do
     it 'returns a Metric instance' do
+      expect(method_call).to receive(:real_time).and_return(4.0001)
+      expect(method_call).to receive(:cpu_time).and_return(3.0001)
+
       method_call.measure { 'foo' }
       metric = method_call.to_metric
 
       expect(metric).to be_an_instance_of(Gitlab::Metrics::Metric)
       expect(metric.series).to eq('rails_method_calls')
 
-      expect(metric.values[:duration]).to be_a_kind_of(Numeric)
-      expect(metric.values[:cpu_duration]).to be_a_kind_of(Numeric)
+      expect(metric.values[:duration]).to eq(4000)
+      expect(metric.values[:cpu_duration]).to eq(3000)
       expect(metric.values[:call_count]).to be_an(Integer)
 
       expect(metric.tags).to eq({ method: 'Foo#bar' })
@@ -116,13 +119,13 @@ describe Gitlab::Metrics::MethodCall do
     end
 
     it 'returns false when the total call time is not above the threshold' do
-      expect(method_call).to receive(:real_time).and_return(9)
+      expect(method_call).to receive(:real_time).and_return(0.009)
 
       expect(method_call.above_threshold?).to eq(false)
     end
 
     it 'returns true when the total call time is above the threshold' do
-      expect(method_call).to receive(:real_time).and_return(9000)
+      expect(method_call).to receive(:real_time).and_return(9)
 
       expect(method_call.above_threshold?).to eq(true)
     end
diff --git a/spec/lib/gitlab/metrics/system_spec.rb b/spec/lib/gitlab/metrics/system_spec.rb
index 4d94d8705fb..14afcdf5daa 100644
--- a/spec/lib/gitlab/metrics/system_spec.rb
+++ b/spec/lib/gitlab/metrics/system_spec.rb
@@ -29,19 +29,19 @@ describe Gitlab::Metrics::System do
 
   describe '.cpu_time' do
     it 'returns a Fixnum' do
-      expect(described_class.cpu_time).to be_an(Integer)
+      expect(described_class.cpu_time).to be_an(Float)
     end
   end
 
   describe '.real_time' do
     it 'returns a Fixnum' do
-      expect(described_class.real_time).to be_an(Integer)
+      expect(described_class.real_time).to be_an(Float)
     end
   end
 
   describe '.monotonic_time' do
-    it 'returns a Fixnum' do
-      expect(described_class.monotonic_time).to be_an(Integer)
+    it 'returns a Float' do
+      expect(described_class.monotonic_time).to be_an(Float)
     end
   end
 end