+ opentelemetry: Add metrics support

build.sbt

@@ -963,8 +963,10 @@ lazy val `kamon-opentelemetry` = (project in file("reporters/kamon-opentelemetry
   .disablePlugins(AssemblyPlugin)
   .settings(
     libraryDependencies ++= Seq(
-      "io.opentelemetry" % "opentelemetry-exporter-otlp-http-trace" % "1.13.0",
-      "io.opentelemetry" % "opentelemetry-exporter-otlp-trace" % "1.13.0",
+      "io.opentelemetry" % "opentelemetry-exporter-otlp-http-trace" % "1.14.0",
+      "io.opentelemetry" % "opentelemetry-exporter-otlp-trace" % "1.14.0",
+      "io.opentelemetry" % "opentelemetry-exporter-otlp-http-metrics" % "1.14.0",
+      "io.opentelemetry" % "opentelemetry-exporter-otlp-metrics" % "1.14.0",
       // Compile-time dependency required in scala 3
       "com.google.auto.value" % "auto-value-annotations" % "1.9" % "compile",
 

reporters/kamon-opentelemetry/src/main/resources/reference.conf

@@ -27,6 +27,27 @@ kamon.otel {
   attributes = ""
   attributes = ${?OTEL_RESOURCE_ATTRIBUTES}
 
+  metrics {
+      endpoint = ${kamon.otel.endpoint}
+      full-endpoint = ${?OTEL_EXPORTER_OTLP_METRICS_ENDPOINT}
+
+      compression = ${kamon.otel.compression}
+      compression = ${?OTEL_EXPORTER_OTLP_METRICS_COMPRESSION}
+
+      headers = ${kamon.otel.headers}
+      headers = ${?OTEL_EXPORTER_OTLP_METRICS_HEADERS}
+
+      timeout = ${kamon.otel.timeout}
+      timeout = ${?OTEL_EXPORTER_OTLP_METRICS_TIMEOUT}
+
+      protocol = ${kamon.otel.protocol}
+      protocol = ${?OTEL_EXPORTER_OTLP_METRICS_PROTOCOL}
+
+      # explicit_bucket_histogram or base2_exponential_bucket_histogram
+      histogram-format = explicit_bucket_histogram
+      histogram-format = ${?OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION}
+  }
+
   trace {
       endpoint = ${kamon.otel.endpoint}
       full-endpoint = ${?OTEL_EXPORTER_OTLP_TRACES_ENDPOINT}
@@ -47,6 +68,48 @@ kamon.otel {
       # standard attribute names; enable for 'more full' compliance with otel standard
       include-error-event = false
   }
+
+  explicit-histo-boundaries {
+    # Same as defaults from https://opentelemetry.io/docs/specs/otel/metrics/sdk/#explicit-bucket-histogram-aggregation
+    default-buckets = [
+      0, 5, 10, 25, 50, 75, 100, 250, 500, 750, 1000, 2500, 5000, 7500, 10000
+    ]
+
+    # The following are the same as for the prometheus reporter default values
+    time-buckets = [
+      0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10
+    ]
+
+    information-buckets = [
+      512, 1024, 2048, 4096, 16384, 65536, 524288, 1048576
+    ]
+
+    percentage-buckets = [
+      20, 40, 60, 70, 80, 90, 95
+    ]
+
+    # Per metric overrides are possible by specifying the metric name and the histogram buckets here
+    custom {
+      // example:
+      // "akka.actor.processing-time" = [0.1, 1.0, 10.0]
+    }
+  }
+
+  exponential-histo-boundaries {
+    default-bucket-count = 160
+
+    time-bucket-count = 160
+
+    information-bucket-count = 160
+
+    percentage-bucket-count = 100
+
+    # Per metric overrides are possible by specifying the metric name and the histogram buckets here
+    custom {
+      // example:
+      // "akka.actor.processing-time" = 3
+    }
+  }
 }
 
 # Arbitrary key-value pairs that further identify the environment where this service instance is running.
@@ -64,7 +127,13 @@ kamon.modules {
   otel-trace-reporter {
     enabled = true
     name = "OpenTelemetry Trace Reporter"
-    description = "Sends trace data to a OpenTelemetry server via gRPC"
+    description = "Sends trace data to a OpenTelemetry server via gRPC/HTTP+protobuf"
     factory = "kamon.otel.OpenTelemetryTraceReporter$Factory"
   }
+  otel-metrics-reporter {
+    enabled = true
+    name = "OpenTelemetry Metrics Reporter"
+    description = "Sends metrics data to a OpenTelemetry server via gRPC/HTTP+protobuf"
+    factory = "kamon.otel.OpenTelemetryMetricsReporter$Factory"
+  }
 }