fix labels handling

lib/prometheus_exporter/ext/instrumentation/base_stats.rb

@@ -29,12 +29,12 @@ def collect_data(data)
       @client.send_json(metric)
     end
 
-    # @param datum [Hash]
+    # @param data [Hash]
     # @return [Hash]
-    def build_metric(datum)
-      metric = datum.dup
+    def build_metric(data)
+      metric = data.dup
       metric[:type] = type
-      metric[:metric_labels] = @metric_labels
+      metric[:labels] = (metric[:labels] || {}).merge(@metric_labels)
       metric
     end
   end

lib/prometheus_exporter/ext/server/stats_collector.rb

@@ -59,7 +59,7 @@ def fill_observers(obj, labels)
       def build_labels(obj)
         labels = {}
         labels.merge!(obj['labels']) if obj['labels']
-        labels.merge!(obj['metric_labels']) if obj['metric_labels']
+        labels.merge!(obj['custom_labels']) if obj['custom_labels']
 
         labels
       end

spec/prometheus_exporter/ext/instrumentation/base_stats_spec.rb

@@ -27,14 +27,12 @@
         {
           type: 'test',
           foo: 123, bar: 456,
-          labels: { qwe: 'asd' },
-          metric_labels: {}
+          labels: { qwe: 'asd' }
         },
         {
           type: 'test',
           foo: 124, bar: 457,
-          labels: { qwe: 'zxc' },
-          metric_labels: {}
+          labels: { qwe: 'zxc' }
         }
       ]
     )

spec/prometheus_exporter/ext/server/stats_collector_spec.rb

@@ -0,0 +1,123 @@
+# frozen_string_literal: true
+
+RSpec.describe PrometheusExporter::Ext::Server::StatsCollector do
+  subject do
+    collector.collect(stringified_metric)
+  end
+
+  let(:collector) { TestCollector.new }
+  let(:stringified_metric) { JSON.parse JSON.generate(metric) }
+  let(:metric) do
+    {
+      type: 'test',
+      labels: { qwe: 'asd' },
+      g_metric: 1.23,
+      gwt_metric: 4.56,
+      c_metric: 7.89
+    }
+  end
+  let(:expected_labels) { metric[:labels] }
+
+  it 'observes prometheus metrics' do
+    subject
+    expect(collector.metrics).to contain_exactly(
+      a_gauge_metric('test_g_metric').with(1.23, expected_labels),
+      a_gauge_with_time_metric('test_gwt_metric').with([4.56, ms_since_epoch], expected_labels),
+      a_counter_metric('test_c_metric').with(7.89, expected_labels)
+    )
+  end
+
+  context 'with empty custom_labels' do
+    let(:metric) do
+      super().merge custom_labels: {}
+    end
+
+    it 'observes prometheus metrics' do
+      subject
+      expect(collector.metrics).to contain_exactly(
+        a_gauge_metric('test_g_metric').with(1.23, expected_labels),
+        a_gauge_with_time_metric('test_gwt_metric').with([4.56, ms_since_epoch],
+                                                         expected_labels
+                                                        ),
+        a_counter_metric('test_c_metric').with(7.89, expected_labels)
+      )
+    end
+  end
+
+  context 'with filled custom_labels' do
+    let(:metric) do
+      super().merge custom_labels: { host: 'example.com' }
+    end
+    let(:expected_labels) { metric[:labels].merge metric[:custom_labels] }
+
+    it 'observes prometheus metrics' do
+      subject
+      expect(collector.metrics).to contain_exactly(
+        a_gauge_metric('test_g_metric').with(1.23, expected_labels),
+        a_gauge_with_time_metric('test_gwt_metric').with([4.56, ms_since_epoch], expected_labels),
+        a_counter_metric('test_c_metric').with(7.89, expected_labels)
+      )
+    end
+  end
+
+  context 'when collector has previous metrics with same labels' do
+    let(:prev_stringified_metric) { JSON.parse JSON.generate(prev_metric) }
+    let(:prev_metric) do
+      {
+        type: 'test',
+        labels: { qwe: 'asd' },
+        g_metric: 10,
+        gwt_metric: 20,
+        c_metric: 30
+      }
+    end
+
+    before do
+      collector.collect(prev_stringified_metric)
+    end
+
+    it 'observes prometheus metrics' do
+      subject
+      expect(collector.metrics).to contain_exactly(
+        a_gauge_metric('test_g_metric').with(1.23, expected_labels),
+        a_gauge_with_time_metric('test_gwt_metric').with([4.56, ms_since_epoch],
+                                                         expected_labels
+                                                        ),
+        a_counter_metric('test_c_metric').with(37.89, expected_labels)
+      )
+    end
+  end
+
+  context 'when collector has previous metrics with different labels' do
+    let(:prev_stringified_metric) { JSON.parse JSON.generate(prev_metric) }
+    let(:prev_metric) do
+      {
+        type: 'test',
+        labels: { qwe: 'asd2' },
+        g_metric: 10,
+        gwt_metric: 20,
+        c_metric: 30
+      }
+    end
+    let(:prev_expected_labels) { prev_metric[:labels] }
+
+    before do
+      collector.collect(prev_stringified_metric)
+    end
+
+    it 'observes prometheus metrics' do
+      subject
+      expect(collector.metrics).to contain_exactly(
+        a_gauge_metric('test_g_metric')
+          .with(10, prev_expected_labels)
+          .with(1.23, expected_labels),
+        a_gauge_with_time_metric('test_gwt_metric')
+          .with([20, ms_since_epoch], prev_expected_labels)
+          .with([4.56, ms_since_epoch], expected_labels),
+        a_counter_metric('test_c_metric')
+          .with(30, prev_expected_labels)
+          .with(7.89, expected_labels)
+      )
+    end
+  end
+end

spec/spec_helper.rb

@@ -1,9 +1,13 @@
 # frozen_string_literal: true
 
 require 'prometheus_exporter'
+require 'prometheus_exporter/server'
 require 'prometheus_exporter/ext'
 require 'prometheus_exporter/ext/rspec'
 require 'prometheus_exporter/ext/instrumentation/base_stats'
+require 'prometheus_exporter/ext/server/stats_collector'
+
+RSpec::Support::ObjectFormatter.default_instance.max_formatted_output_length = nil
 
 class TestInstrumentation < PrometheusExporter::Ext::Instrumentation::BaseStats
   self.type = 'test'
@@ -15,6 +19,15 @@ def collect(data_list)
   end
 end
 
+class TestCollector < PrometheusExporter::Server::TypeCollector
+  include PrometheusExporter::Ext::Server::StatsCollector
+  self.type = 'test'
+
+  register_metric :g_metric, :gauge, 'test gauge metric'
+  register_metric :gwt_metric, :gauge_with_time, 'test gauge with time metric'
+  register_metric :c_metric, :counter, 'test counter metric'
+end
+
 RSpec.configure do |config|
   # Enable flags like --only-failures and --next-failure
   config.example_status_persistence_file_path = '.rspec_status'