Ship ZIO Metrics to OpenTelemetry (OLTP gRPC) using zio-telemetry-opentelemetry by manually providing the instrumentation (this portion connects ZIO Metrics to the ZIO Opentelemetry machinery). I also have an example that uses auto-instrumentation

build.sbt

val scala3Version = "3.6.3"

lazy val root = project
  .in(file("."))
  .settings(
    name         := "zio-telemetry-playground",
    version      := "0.1.0-SNAPSHOT",
    scalaVersion := scala3Version,
    libraryDependencies ++=
      Seq(
        "dev.zio"         %% "zio"                           % "2.1.15",
        "dev.zio"         %% "zio-logging-slf4j-bridge"      % "2.4.0", // route all SLF4J logs to ZIO RTS
        "dev.zio"         %% "zio-opentelemetry"             % "3.1.1", // integration for OTLP metrics + ZIO
        "dev.zio"         %% "zio-opentelemetry-zio-logging" % "3.1.1", // integration for OTLP logs + ZIO
        "io.opentelemetry" % "opentelemetry-sdk"             % "1.47.0",
        "io.opentelemetry" % "opentelemetry-exporter-otlp"   % "1.47.0"
      )
  )

docker-compose.yaml

services:
  otel-lgtm:
    image: grafana/otel-lgtm:latest
    container_name: otel-lgtm
    ports:
      - "3000:3000"  # Grafana UI
      - "4317:4317"  # OpenTelemetry Collector gRPC
      - "4318:4318"  # OpenTelemetry Collector HTTP
    volumes:
      - ./otel-lgtm-data:/var/lib/grafana

Playground.scala

import zio.*
import zio.telemetry.opentelemetry.OpenTelemetry
import io.opentelemetry.sdk.OpenTelemetrySdk
import io.opentelemetry.api.metrics.MeterProvider
import io.opentelemetry.sdk.metrics.SdkMeterProvider
import io.opentelemetry.exporter.otlp.metrics.OtlpGrpcMetricExporter
import io.opentelemetry.exporter.otlp.logs.OtlpGrpcLogRecordExporter
import io.opentelemetry.sdk.metrics.`export`.PeriodicMetricReader
import io.opentelemetry.sdk.resources.Resource as OltpResource
import zio.metrics.Metric
import java.util.concurrent.TimeUnit
import zio.metrics.jvm.DefaultJvmMetrics
import io.opentelemetry.sdk.logs.`export`.SimpleLogRecordProcessor
import io.opentelemetry.sdk.logs.`export`.BatchLogRecordProcessor
import io.opentelemetry.sdk.logs.SdkLoggerProvider
import zio.logging.slf4j.bridge.Slf4jBridge

object Main extends ZIOAppDefault:

  override val bootstrap: ZLayer[ZIOAppArgs, Any, Any] =
    // metrics
    val meterProvider: RIO[Scope, SdkMeterProvider] =
      val metricExporter: RIO[Scope, OtlpGrpcMetricExporter] =
        ZIO.fromAutoCloseable:
          ZIO.attempt:
            OtlpGrpcMetricExporter.builder().setEndpoint("http://localhost:4317").build()

      metricExporter
        .flatMap: exporter =>
          ZIO
            .fromAutoCloseable:
              ZIO.attempt:
                PeriodicMetricReader
                  .builder(exporter)
                  .setInterval(5, TimeUnit.SECONDS)
                  .build()
        .map: meterReader =>
          SdkMeterProvider
            .builder()
            .setResource(
              OltpResource
                .builder()
                .put("service.name", "zio-telemetry-playground")
                .put("job", "zio-telemetry-playground")
                .build()
            )
            .registerMetricReader(meterReader)
            .build()

    // logging
    val loggerProvider: RIO[Scope, SdkLoggerProvider] =
      val logExporter =
        ZIO.fromAutoCloseable:
          ZIO.attempt:
            OtlpGrpcLogRecordExporter
              .builder()
              .setEndpoint("http://localhost:4317")
              .setCompression("gzip")
              .build()

      logExporter
        .flatMap: exporter =>
          ZIO.fromAutoCloseable:
            ZIO.attempt:
              BatchLogRecordProcessor
                .builder(exporter)
                .setMaxExportBatchSize(100)
                .build()
        .flatMap: processor =>
          ZIO.fromAutoCloseable:
            ZIO.attempt:
              SdkLoggerProvider
                .builder()
                .setResource(
                  OltpResource
                    .builder()
                    .put("service.name", "zio-telemetry-playground")
                    .put("job", "zio-telemetry-playground")
                    .build()
                )
                .addLogRecordProcessor(processor)
                .build()

    val otelSdkLayer: TaskLayer[OpenTelemetrySdk] =
      ZLayer.scoped:
        for
          meterProvider  <- meterProvider
          loggerProvider <- loggerProvider
          otelSdk <- ZIO.fromAutoCloseable:
                       ZIO.attempt:
                         OpenTelemetrySdk
                           .builder()
                           .setMeterProvider(meterProvider)
                           .setLoggerProvider(loggerProvider)
                           .build()
        yield otelSdk

    Runtime.removeDefaultLoggers >>>
      Slf4jBridge.initialize >>> // route all SLF4J logs to ZIO RTS
      otelSdkLayer >+>
      OpenTelemetry.contextZIO >+>
      OpenTelemetry.metrics("zio-telemetry-playground", None, None) >+>
      OpenTelemetry.logging("zio-telemetry-playground", logLevel = LogLevel.Debug) >+> // log all ZIO logs to OTLP
      OpenTelemetry.zioMetrics >>>                                                     // ship all metrics to OTLP
      DefaultJvmMetrics.live.unit

  override def run =
    val metric: Metric.Counter[Any] =
      Metric
        .counter("test_cal")
        .contramap[Any](_ => 1L)

    (ZIO.logInfo("Hello from cal!")
      @@ ZIOAspect.annotated(
        "bim"  -> "boom",
        "bim2" -> "boom2",
        "bim3" -> "boom3"
      )
      @@ metric).repeat(Schedule.spaced(1.second))

Structured OTLP Logs

Auto instrumentation makes this even easier provided you use the java-agent:

build.sbt

val scala3Version = "3.6.3"

inThisBuild(
  List(
    semanticdbEnabled := true
  )
)

lazy val root = project
  .in(file("."))
  .enablePlugins(JavaAgent)
  .settings(
    name         := "zio-telemetry-playground",
    version      := "0.1.0-SNAPSHOT",
    scalaVersion := scala3Version,
    scalacOptions ++= Seq("-Wunused:imports"),
    javaAgents += "io.opentelemetry.javaagent" % "opentelemetry-javaagent" % "2.13.1" % "compile",
    fork                                      := true,
    libraryDependencies ++=
      Seq(
        "dev.zio"         %% "zio"                           % "2.1.15",
        "dev.zio"         %% "zio-logging-slf4j-bridge"      % "2.4.0", // route all SLF4J logs to ZIO RTS
        "dev.zio"         %% "zio-opentelemetry"             % "3.1.1",
        "dev.zio"         %% "zio-opentelemetry-zio-logging" % "3.1.1",
        "io.opentelemetry" % "opentelemetry-sdk"             % "1.47.0",
        "io.opentelemetry" % "opentelemetry-exporter-otlp"   % "1.47.0"
      )
  )

project/plugins.sbt

addSbtPlugin("org.scalameta"  % "sbt-scalafmt"        % "2.5.4")
addSbtPlugin("ch.epfl.scala"  % "sbt-scalafix"        % "0.14.2")
addSbtPlugin("com.github.sbt" % "sbt-native-packager" % "1.11.1")
addSbtPlugin("com.github.sbt" % "sbt-javaagent"       % "0.1.7")
addSbtPlugin("nl.gn0s1s"      % "sbt-dotenv"          % "3.1.1")

.env

OTEL_SERVICE_NAME="zio-telemetry-auto-example"
OTEL_EXPORTER_OTLP_PROTOCOL="grpc"
OTEL_EXPORTER_OTLP_ENDPOINT="http://localhost:4317"

# 100% sampling rate for traces (we aren't using traces in this example)
OTEL_TRACES_SAMPLER="always_on"

Main.scala

import zio.*
import zio.logging.slf4j.bridge.Slf4jBridge
import zio.metrics.Metric
import zio.metrics.jvm.DefaultJvmMetrics
import zio.telemetry.opentelemetry.OpenTelemetry

object Main extends ZIOAppDefault:

  override val bootstrap: ZLayer[ZIOAppArgs, Any, Any] =
    Runtime.removeDefaultLoggers >>>
      Slf4jBridge.initialize >>>   // route all SLF4J logs to ZIO RTS
      OpenTelemetry.global >+>     // auto-instrumentation handshake (requires javaagent)
      OpenTelemetry.contextJVM >+> // auto-instrumentation context propagation handshake
      OpenTelemetry.metrics("zio-telemetry-playground", None, None) >+>
      OpenTelemetry.logging("zio-telemetry-playground", logLevel = LogLevel.Debug) >+> // log all ZIO logs to OTLP
      OpenTelemetry.zioMetrics >>>                                                     // ship all metrics to OTLP
      DefaultJvmMetrics.live.unit

  override def run =
    val metric: Metric.Counter[Any] =
      Metric
        .counter("test_cal")
        .contramap[Any](_ => 1L)

    (ZIO.logInfo("Hello from cal auto!")
      @@ ZIOAspect.annotated(
        "iam" -> "auto",
        "bim" -> "boom"
      ) @@ metric).repeat(Schedule.spaced(1.second))

An example using zio-telemetry + ZIO showing how to do:

• tracing
• logging
• metrics

Main.scala

import zio.*
import zio.logging.slf4j.bridge.Slf4jBridge
import zio.metrics.Metric
import zio.metrics.jvm.DefaultJvmMetrics
import zio.telemetry.opentelemetry.OpenTelemetry
import zio.telemetry.opentelemetry.context.ContextStorage
import zio.telemetry.opentelemetry.tracing.Tracing

object Main extends ZIOApp:

  override type Environment = ContextStorage & Tracing

  override implicit def environmentTag: EnvironmentTag[Environment] = EnvironmentTag.tagFromTagMacro[Environment]

  override val bootstrap: ZLayer[ZIOAppArgs, Any, Environment] =
    ZLayer.make[Environment](
      Runtime.removeDefaultLoggers,
      Slf4jBridge.initialize,   // route all SLF4J logs to ZIO RTS
      OpenTelemetry.global,     // auto-instrumentation handshake (requires javaagent)
      OpenTelemetry.contextJVM, // auto-instrumentation context propagation handshake
      OpenTelemetry.tracing("zio-telemetry-playground", None, None, logAnnotated = true),
      OpenTelemetry.metrics("zio-telemetry-playground", None, None),
      OpenTelemetry.logging("zio-telemetry-playground", logLevel = LogLevel.Debug), // log all ZIO logs to OTLP
      OpenTelemetry.zioMetrics,                                                     // ship all metrics to OTLP
      DefaultJvmMetrics.live.unit
    )

  override def run =
    val metric: Metric.Counter[Any] =
      Metric
        .counter("test_cal")
        .contramap[Any](_ => 1L)

    ZIO.serviceWithZIO[Tracing]: tracing =>
      (ZIO.logInfo("Hello from cal auto!")
        @@ ZIOAspect.annotated("iam" -> "auto", "bim" -> "boom")
        @@ metric
        @@ tracing.aspects.span("test_span_cal")).repeat(Schedule.spaced(1.second))