feat: include async instrument for otlp exporter (#1855)

* feat: init update async instrument

* feat: asynchronous inst - using meter for multi instrument callback registeration

* feat: asyc instrument - lint and allow setting default attributes for instrument

* feat: asyc instrument - separate callback from instrument init and after init

* feat: asyc - revision

* lint

* update metrics_api

* fix: include async in otlp exporter

* lint

* Apply suggestions from code review

Co-authored-by: Kayla Reopelle <[email protected]>

* merge

---------

Co-authored-by: Kayla Reopelle <[email protected]>

Author: xuan-cao-swi

examples/metrics_sdk/async_metrics_collect.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+require 'bundler/inline'
+
+gemfile(true) do
+  source 'https://rubygems.org'
+  gem "opentelemetry-api"
+  gem "opentelemetry-common"
+  gem "opentelemetry-sdk"
+
+  gem 'opentelemetry-metrics-api', path: '../../metrics_api'
+  gem 'opentelemetry-metrics-sdk', path: '../../metrics_sdk'
+end
+
+require 'opentelemetry/sdk'
+require 'opentelemetry-metrics-sdk'
+
+# this example manually configures the exporter, turn off automatic configuration
+ENV['OTEL_METRICS_EXPORTER'] = 'none'
+
+OpenTelemetry::SDK.configure
+
+console_metric_exporter = OpenTelemetry::SDK::Metrics::Export::ConsoleMetricPullExporter.new
+
+OpenTelemetry.meter_provider.add_metric_reader(console_metric_exporter)
+
+meter = OpenTelemetry.meter_provider.meter("SAMPLE_METER_NAME")
+
+recoverable_callback = proc {
+  cpu_usage = `ps -p #{Process.pid} -o %cpu=`.strip.to_f
+  cpu_usage
+}
+
+ob_counter = meter.create_observable_counter('observable_counter', callback: recoverable_callback, unit: 'ms')
+
+ob_counter.observe
+
+OpenTelemetry.meter_provider.metric_readers.each(&:pull)
+OpenTelemetry.meter_provider.shutdown

exporter/otlp-metrics/lib/opentelemetry/exporter/otlp/metrics/metrics_exporter.rb

@@ -231,7 +231,7 @@ def as_otlp_metrics(metrics)
                 )
               )
 
-            when :counter, :up_down_counter
+            when :counter, :up_down_counter, :observable_counter, :observable_up_down_counter
               Opentelemetry::Proto::Metrics::V1::Metric.new(
                 name: metrics.name,
                 description: metrics.description,

exporter/otlp-metrics/test/opentelemetry/exporter/otlp/metrics/metrics_exporter_test.rb

@@ -560,6 +560,20 @@
       assert_requested(stub_post)
     end
 
+    # when the exporter.pull, it will automatically invoke callback once;
+    # if wants to record data (invoke callback) with attributes, do async_counter.observe(timeout, attributes)
+    it 'exports an async metric' do
+      stub_post = stub_request(:post, 'http://localhost:4318/v1/metrics').to_return(status: 200)
+      meter_provider.add_metric_reader(exporter)
+      meter       = meter_provider.meter('test')
+      pf_callback = proc { 10 }
+      meter.create_observable_counter('test_async_counter', callback: pf_callback, unit: 'smidgen', description: 'a small amount of something')
+      exporter.pull
+      meter_provider.shutdown
+
+      assert_requested(stub_post)
+    end
+
     it 'compresses with gzip if enabled' do
       exporter = OpenTelemetry::Exporter::OTLP::Metrics::MetricsExporter.new(compression: 'gzip')
       stub_post = stub_request(:post, 'http://localhost:4318/v1/metrics').to_return do |request|
@@ -614,6 +628,10 @@
       exponential_histogram = meter.create_histogram('test_exponential_histogram', unit: 'smidgen', description: 'a small amount of something')
       exponential_histogram.record(20, attributes: { 'lox' => 'xol' })
 
+      pf_callback = proc { 30 }
+      async_gauge = meter.create_observable_gauge('test_async_gauge', callback: pf_callback, unit: 'smidgen', description: 'a small amount of something')
+      async_gauge.observe(attributes: { 'foo' => 'bar' })
+
       exporter.pull
       meter_provider.shutdown
 
@@ -750,6 +768,31 @@
                         ],
                         aggregation_temporality: Opentelemetry::Proto::Metrics::V1::AggregationTemporality::AGGREGATION_TEMPORALITY_DELTA
                       )
+                    ),
+                    Opentelemetry::Proto::Metrics::V1::Metric.new(
+                      name: 'test_async_gauge',
+                      description: 'a small amount of something',
+                      unit: 'smidgen',
+                      gauge: Opentelemetry::Proto::Metrics::V1::Gauge.new(
+                        data_points: [
+                          Opentelemetry::Proto::Metrics::V1::NumberDataPoint.new(
+                            attributes: [
+                              Opentelemetry::Proto::Common::V1::KeyValue.new(key: 'foo', value: Opentelemetry::Proto::Common::V1::AnyValue.new(string_value: 'bar'))
+                            ],
+                            as_int: 30,
+                            start_time_unix_nano: 1_699_593_427_329_946_585,
+                            time_unix_nano: 1_699_593_427_329_946_586,
+                            exemplars: nil
+                          ),
+                          Opentelemetry::Proto::Metrics::V1::NumberDataPoint.new(
+                            attributes: [],
+                            as_int: 30,
+                            start_time_unix_nano: 1_699_593_427_329_946_585,
+                            time_unix_nano: 1_699_593_427_329_946_586,
+                            exemplars: nil
+                          )
+                        ]
+                      )
                     )
                   ]
                 )

metrics_sdk/lib/opentelemetry/sdk/metrics/instrument/observable_counter.rb

@@ -18,7 +18,7 @@ def instrument_kind
             :observable_counter
           end
 
-          # Observe the Counter with fixed timeout duration.
+          # Observe the ObservableCounter with fixed timeout duration.
           #
           # @param [int] timeout The timeout duration for callback to run, which MUST be a non-negative numeric value.
           # @param [Hash{String => String, Numeric, Boolean, Array<String, Numeric, Boolean>}] attributes
@@ -32,7 +32,7 @@ def observe(timeout: nil, attributes: {})
           private
 
           def default_aggregation
-            OpenTelemetry::SDK::Metrics::Aggregation::Sum.new
+            OpenTelemetry::SDK::Metrics::Aggregation::Sum.new(monotonic: true)
           end
         end
       end

metrics_sdk/lib/opentelemetry/sdk/metrics/instrument/observable_gauge.rb

@@ -32,7 +32,7 @@ def observe(timeout: nil, attributes: {})
           private
 
           def default_aggregation
-            OpenTelemetry::SDK::Metrics::Aggregation::Sum.new
+            OpenTelemetry::SDK::Metrics::Aggregation::LastValue.new
           end
         end
       end

metrics_sdk/lib/opentelemetry/sdk/metrics/instrument/observable_up_down_counter.rb

@@ -32,7 +32,7 @@ def observe(timeout: nil, attributes: {})
           private
 
           def default_aggregation
-            OpenTelemetry::SDK::Metrics::Aggregation::Sum.new(aggregation_temporality: :delta)
+            OpenTelemetry::SDK::Metrics::Aggregation::Sum.new(aggregation_temporality: :delta, monotonic: false)
           end
         end
       end

metrics_sdk/test/opentelemetry/sdk/metrics/instrument/observable_gauge_test.rb

@@ -29,7 +29,7 @@
     _(last_snapshot[0].instrumentation_scope.name).must_equal('test')
     _(last_snapshot[0].data_points[0].value).must_equal(10)
     _(last_snapshot[0].data_points[0].attributes).must_equal({})
-    _(last_snapshot[0].aggregation_temporality).must_equal(:cumulative)
+    _(last_snapshot[0].aggregation_temporality).must_equal(:delta)
   end
 
   it 'counts with observe' do
@@ -49,6 +49,6 @@
 
     _(last_snapshot[0].data_points[1].value).must_equal(10)
     _(last_snapshot[0].data_points[1].attributes).must_equal({})
-    _(last_snapshot[0].aggregation_temporality).must_equal(:cumulative)
+    _(last_snapshot[0].aggregation_temporality).must_equal(:delta)
   end
 end