Custom histogram metric buckets

temporalio/ext/src/runtime.rs

@@ -14,6 +14,7 @@ use temporal_sdk_core::telemetry::{
     build_otlp_metric_exporter, start_prometheus_metric_exporter, MetricsCallBuffer,
 };
 use temporal_sdk_core::{CoreRuntime, TokioRuntimeBuilder};
+use temporal_sdk_core_api::telemetry::HistogramBucketOverrides;
 use temporal_sdk_core_api::telemetry::{
     metrics::MetricCallBufferer, Logger, MetricTemporality, OtelCollectorOptionsBuilder,
     OtlpProtocol, PrometheusExporterOptionsBuilder, TelemetryOptionsBuilder,
@@ -129,6 +130,9 @@ impl Runtime {
                     if opentelemetry.member::<bool>(id!("http"))? {
                         opts_build.protocol(OtlpProtocol::Http);
                     }
+                    if let Some(overrides) = opentelemetry.member::<Option<HashMap<String, Vec<f64>>>>(id!("histogram_bucket_overrides"))? {
+                        opts_build.histogram_bucket_overrides(HistogramBucketOverrides { overrides });
+                    }
                     let opts = opts_build
                         .build()
                         .map_err(|err| error!("Invalid OpenTelemetry options: {}", err))?;
@@ -150,6 +154,9 @@ impl Runtime {
                     if let Some(global_tags) = metrics.member::<Option<HashMap<String, String>>>(id!("global_tags"))? {
                         opts_build.global_tags(global_tags);
                     }
+                    if let Some(overrides) = prom.member::<Option<HashMap<String, Vec<f64>>>>(id!("histogram_bucket_overrides"))? {
+                        opts_build.histogram_bucket_overrides(HistogramBucketOverrides { overrides });
+                    }
                     let opts = opts_build
                         .build()
                         .map_err(|err| error!("Invalid Prometheus options: {}", err))?;

temporalio/lib/temporalio/internal/bridge/runtime.rb

@@ -38,6 +38,7 @@ class Runtime
           :metric_temporality_delta,
           :durations_as_seconds,
           :http,
+          :histogram_bucket_overrides, # Optional
           keyword_init: true
         )
 
@@ -46,6 +47,7 @@ class Runtime
           :counters_total_suffix,
           :unit_suffix,
           :durations_as_seconds,
+          :histogram_bucket_overrides, # Optional
           keyword_init: true
         )
       end

temporalio/lib/temporalio/runtime.rb

@@ -178,7 +178,8 @@ def _to_bridge
       :metric_periodicity,
       :metric_temporality,
       :durations_as_seconds,
-      :http
+      :http,
+      :histogram_bucket_overrides
     )
 
     # Options for exporting metrics to OpenTelemetry.
@@ -197,6 +198,9 @@ def _to_bridge
     #     +false+.
     # @!attribute http
     #   @return [Boolean] True if the protocol is HTTP, false if gRPC (the default).
+    # @!attribute histogram_bucket_overrides
+    #   @return [Hash<String, Array<Numeric>>, nil] Override default histogram buckets. Key of the hash it the metric
+    #     name, value is an array of floats for the set of buckets.
     class OpenTelemetryMetricsOptions
       # OpenTelemetry metric temporality.
       module MetricTemporality
@@ -213,13 +217,16 @@ module MetricTemporality
       # @param durations_as_seconds [Boolean] Whether to use float seconds instead of integer milliseconds for
       #   durations.
       # @param http [Boolean] True if the protocol is HTTP, false if gRPC (the default).
+      # @param histogram_bucket_overrides [Hash<String, Array<Numeric>>, nil] Override default histogram buckets. Key of
+      #   the hash it the metric name, value is an array of floats for the set of buckets.
       def initialize(
         url:,
         headers: nil,
         metric_periodicity: nil,
         metric_temporality: MetricTemporality::CUMULATIVE,
         durations_as_seconds: false,
-        http: false
+        http: false,
+        histogram_bucket_overrides: nil
       )
         super
       end
@@ -237,7 +244,8 @@ def _to_bridge
                                     else raise 'Unrecognized metric temporality'
                                     end,
           durations_as_seconds:,
-          http:
+          http:,
+          histogram_bucket_overrides:
         )
       end
     end
@@ -246,7 +254,8 @@ def _to_bridge
       :bind_address,
       :counters_total_suffix,
       :unit_suffix,
-      :durations_as_seconds
+      :durations_as_seconds,
+      :histogram_bucket_overrides
     )
 
     # Options for exporting metrics to Prometheus.
@@ -259,6 +268,9 @@ def _to_bridge
     #   @return [Boolean] If `true`, all histograms will include the unit in their name as a suffix.
     # @!attribute durations_as_seconds
     #   @return [Boolean] Whether to use float seconds instead of integer milliseconds for durations.
+    # @!attribute histogram_bucket_overrides
+    #   @return [Hash<String, Array<Numeric>>, nil] Override default histogram buckets. Key of the hash it the metric
+    #     name, value is an array of floats for the set of buckets.
     class PrometheusMetricsOptions
       # Create Prometheus options.
       #
@@ -267,11 +279,14 @@ class PrometheusMetricsOptions
       # @param unit_suffix [Boolean] If `true`, all histograms will include the unit in their name as a suffix.
       # @param durations_as_seconds [Boolean] Whether to use float seconds instead of integer milliseconds for
       #   durations.
+      # @param histogram_bucket_overrides [Hash<String, Array<Numeric>>, nil] Override default histogram buckets. Key of
+      #   the hash it the metric name, value is an array of floats for the set of buckets.
       def initialize(
         bind_address:,
         counters_total_suffix: false,
         unit_suffix: false,
-        durations_as_seconds: false
+        durations_as_seconds: false,
+        histogram_bucket_overrides: nil
       )
         super
       end
@@ -283,7 +298,8 @@ def _to_bridge
           bind_address:,
           counters_total_suffix:,
           unit_suffix:,
-          durations_as_seconds:
+          durations_as_seconds:,
+          histogram_bucket_overrides:
         )
       end
     end

temporalio/sig/temporalio/internal/bridge/runtime.rbs

@@ -51,14 +51,16 @@ module Temporalio
           attr_accessor metric_temporality_delta: bool
           attr_accessor durations_as_seconds: bool
           attr_accessor http: bool
+          attr_accessor histogram_bucket_overrides: Hash[String, Array[Numeric]]?
 
           def initialize: (
             url: String,
             headers: Hash[String, String]?,
             metric_periodicity: Float?,
             metric_temporality_delta: bool,
             durations_as_seconds: bool,
-            http: bool
+            http: bool,
+            histogram_bucket_overrides: Hash[String, Array[Numeric]]?
           ) -> void
         end
 
@@ -67,12 +69,14 @@ module Temporalio
           attr_accessor counters_total_suffix: bool
           attr_accessor unit_suffix: bool
           attr_accessor durations_as_seconds: bool
+          attr_accessor histogram_bucket_overrides: Hash[String, Array[Numeric]]?
 
           def initialize: (
             bind_address: String,
             counters_total_suffix: bool,
             unit_suffix: bool,
-            durations_as_seconds: bool
+            durations_as_seconds: bool,
+            histogram_bucket_overrides: Hash[String, Array[Numeric]]?
           ) -> void
         end
 

temporalio/sig/temporalio/runtime.rbs

@@ -70,14 +70,16 @@ module Temporalio
       attr_reader metric_temporality: MetricTemporality
       attr_reader durations_as_seconds: bool
       attr_reader http: bool
+      attr_reader histogram_bucket_overrides: Hash[String, Array[Numeric]]?
 
       def initialize: (
         url: String,
         ?headers: Hash[String, String]?,
         ?metric_periodicity: Float?,
         ?metric_temporality: MetricTemporality,
         ?durations_as_seconds: bool,
-        ?http: bool
+        ?http: bool,
+        ?histogram_bucket_overrides: Hash[String, Array[Numeric]]?
       ) -> void
 
       def _to_bridge: -> Internal::Bridge::Runtime::OpenTelemetryMetricsOptions
@@ -88,12 +90,14 @@ module Temporalio
       attr_reader counters_total_suffix: bool
       attr_reader unit_suffix: bool
       attr_reader durations_as_seconds: bool
+      attr_reader histogram_bucket_overrides: Hash[String, Array[Numeric]]?
 
       def initialize: (
         bind_address: String,
         ?counters_total_suffix: bool,
         ?unit_suffix: bool,
-        ?durations_as_seconds: bool
+        ?durations_as_seconds: bool,
+        ?histogram_bucket_overrides: Hash[String, Array[Numeric]]?
       ) -> void
 
       def _to_bridge: -> Internal::Bridge::Runtime::PrometheusMetricsOptions

temporalio/test/runtime_test.rb

@@ -127,4 +127,43 @@ def test_metric_basics
     assert_bad_call { counter_int.record(1, additional_attributes: { 123 => 'foo' }) }
     # steep:ignore:end
   end
+
+  def test_histogram_bucket_overrides
+    # Prom metrics with custom histogram buckets
+    prom_addr = "127.0.0.1:#{find_free_port}"
+    runtime = Temporalio::Runtime.new(
+      telemetry: Temporalio::Runtime::TelemetryOptions.new(
+        metrics: Temporalio::Runtime::MetricsOptions.new(
+          prometheus: Temporalio::Runtime::PrometheusMetricsOptions.new(
+            bind_address: prom_addr,
+            histogram_bucket_overrides: {
+              'temporal_request_latency' => [123.4, 567.89],
+              'custom_histogram' => [5, 6, 7]
+            }
+          )
+        )
+      )
+    )
+    conn_opts = env.client.connection.options.with(runtime:)
+    client_opts = env.client.options.with(
+      connection: Temporalio::Client::Connection.new(**conn_opts.to_h) # steep:ignore
+    )
+    client = Temporalio::Client.new(**client_opts.to_h) # steep:ignore
+
+    # Generate metrics
+    client.workflow_service.get_system_info(Temporalio::Api::WorkflowService::V1::GetSystemInfoRequest.new)
+    hist = runtime.metric_meter.create_metric(:histogram, 'custom_histogram', value_type: :float)
+    hist.record(4.5)
+    hist.record(5.5)
+    hist.record(6.5)
+    hist.record(7.5)
+
+    # Check metrics
+    dump = Net::HTTP.get(URI("http://#{prom_addr}/metrics"))
+    assert_metric_line(dump, 'temporal_request_latency_bucket', le: '123.4')
+    assert_metric_line(dump, 'temporal_request_latency_bucket', le: '567.89')
+    assert_equal '1', assert_metric_line(dump, 'custom_histogram_bucket', le: '5')
+    assert_equal '2', assert_metric_line(dump, 'custom_histogram_bucket', le: '6')
+    assert_equal '3', assert_metric_line(dump, 'custom_histogram_bucket', le: '7')
+  end
 end