Add User-Agent header to OTLP exporter requests

exporters/otlp/all/src/main/java/io/opentelemetry/exporter/otlp/http/metrics/OtlpHttpMetricExporterBuilder.java

@@ -9,6 +9,7 @@
 import static java.util.Objects.requireNonNull;
 
 import io.opentelemetry.exporter.internal.okhttp.OkHttpExporterBuilder;
+import io.opentelemetry.exporter.internal.otlp.OtlpUserAgent;
 import io.opentelemetry.exporter.internal.otlp.metrics.MetricsRequestMarshaler;
 import io.opentelemetry.sdk.metrics.InstrumentType;
 import io.opentelemetry.sdk.metrics.export.AggregationTemporalitySelector;
@@ -38,6 +39,7 @@ public final class OtlpHttpMetricExporterBuilder {
 
   OtlpHttpMetricExporterBuilder() {
     delegate = new OkHttpExporterBuilder<>("otlp", "metric", DEFAULT_ENDPOINT);
+    OtlpUserAgent.addUserAgentHeader(delegate::addHeader);
   }
 
   /**

exporters/otlp/all/src/main/java/io/opentelemetry/exporter/otlp/http/trace/OtlpHttpSpanExporterBuilder.java

@@ -10,6 +10,7 @@
 
 import io.opentelemetry.api.metrics.MeterProvider;
 import io.opentelemetry.exporter.internal.okhttp.OkHttpExporterBuilder;
+import io.opentelemetry.exporter.internal.otlp.OtlpUserAgent;
 import io.opentelemetry.exporter.internal.otlp.traces.TraceRequestMarshaler;
 import java.time.Duration;
 import java.util.concurrent.TimeUnit;
@@ -27,6 +28,7 @@ public final class OtlpHttpSpanExporterBuilder {
 
   OtlpHttpSpanExporterBuilder() {
     delegate = new OkHttpExporterBuilder<>("otlp", "span", DEFAULT_ENDPOINT);
+    OtlpUserAgent.addUserAgentHeader(delegate::addHeader);
   }
 
   /**

exporters/otlp/all/src/main/java/io/opentelemetry/exporter/otlp/metrics/OtlpGrpcMetricExporterBuilder.java

@@ -11,6 +11,7 @@
 import io.grpc.ManagedChannel;
 import io.opentelemetry.exporter.internal.grpc.GrpcExporter;
 import io.opentelemetry.exporter.internal.grpc.GrpcExporterBuilder;
+import io.opentelemetry.exporter.internal.otlp.OtlpUserAgent;
 import io.opentelemetry.exporter.internal.otlp.metrics.MetricsRequestMarshaler;
 import io.opentelemetry.sdk.metrics.InstrumentType;
 import io.opentelemetry.sdk.metrics.export.AggregationTemporalitySelector;
@@ -56,6 +57,7 @@ public final class OtlpGrpcMetricExporterBuilder {
             DEFAULT_ENDPOINT,
             () -> MarshalerMetricsServiceGrpc::newFutureStub,
             GRPC_ENDPOINT_PATH);
+    OtlpUserAgent.addUserAgentHeader(delegate::addHeader);
   }
 
   /**

exporters/otlp/all/src/main/java/io/opentelemetry/exporter/otlp/trace/OtlpGrpcSpanExporterBuilder.java

@@ -12,6 +12,7 @@
 import io.opentelemetry.api.metrics.MeterProvider;
 import io.opentelemetry.exporter.internal.grpc.GrpcExporter;
 import io.opentelemetry.exporter.internal.grpc.GrpcExporterBuilder;
+import io.opentelemetry.exporter.internal.otlp.OtlpUserAgent;
 import io.opentelemetry.exporter.internal.otlp.traces.TraceRequestMarshaler;
 import java.net.URI;
 import java.time.Duration;
@@ -41,6 +42,7 @@ public final class OtlpGrpcSpanExporterBuilder {
             DEFAULT_ENDPOINT,
             () -> MarshalerTraceServiceGrpc::newFutureStub,
             GRPC_ENDPOINT_PATH);
+    OtlpUserAgent.addUserAgentHeader(delegate::addHeader);
   }
 
   /**

exporters/otlp/common/build.gradle.kts

@@ -9,7 +9,7 @@ plugins {
 }
 
 description = "OpenTelemetry Protocol Exporter"
-otelJava.moduleName.set("io.opentelemetry.exporter.otlp.internal")
+otelJava.moduleName.set("io.opentelemetry.exporter.internal.otlp")
 
 val versions: Map<String, String> by project
 dependencies {

exporters/otlp/common/src/main/java/io/opentelemetry/exporter/internal/otlp/OtlpUserAgent.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.exporter.internal.otlp;
+
+import java.util.Properties;
+import java.util.function.BiConsumer;
+
+/**
+ * This class is internal and is hence not for public use. Its APIs are unstable and can change at
+ * any time.
+ */
+public final class OtlpUserAgent {
+
+  private static final String userAgent = "OTel OTLP Exporter Java/" + readVersion();
+
+  private static String readVersion() {
+    Properties properties = new Properties();
+    try {
+      properties.load(OtlpUserAgent.class.getResourceAsStream("version.properties"));
+    } catch (Exception e) {
+      // we left the attribute empty
+      return "unknown";
+    }
+    return properties.getProperty("sdk.version", "unknown");
+  }
+
+  /**
+   * Return an OTLP {@code User-Agent} header value of the form {@code "OTel OTLP Exporter
+   * Java/{version}"}.
+   *
+   * @see <a
+   *     href="https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md#user-agent">OTLP
+   *     Exporter User Agent</a>
+   */
+  public static String getUserAgent() {
+    return userAgent;
+  }
+
+  /**
+   * Call the {@code consumer with} an OTLP {@code User-Agent} header value of the form {@code "OTel
+   * OTLP Exporter Java/{version}"}.
+   *
+   * @see <a
+   *     href="https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md#user-agent">OTLP
+   *     Exporter User Agent</a>
+   */
+  public static void addUserAgentHeader(BiConsumer<String, String> consumer) {
+    consumer.accept("User-Agent", userAgent);
+  }
+
+  private OtlpUserAgent() {}
+}

exporters/otlp/common/src/test/java/io/opentelemetry/exporter/internal/otlp/OtlpUserAgentTest.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.exporter.internal.otlp;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.concurrent.atomic.AtomicReference;
+import org.junit.jupiter.api.Test;
+
+class OtlpUserAgentTest {
+
+  @Test
+  void getUserAgent() {
+    assertThat(OtlpUserAgent.getUserAgent()).matches("OTel OTLP Exporter Java/1\\..*");
+  }
+
+  @Test
+  void addUserAgentHeader() {
+    AtomicReference<String> keyRef = new AtomicReference<>();
+    AtomicReference<String> valueRef = new AtomicReference<>();
+    OtlpUserAgent.addUserAgentHeader(
+        (key, value) -> {
+          keyRef.set(key);
+          valueRef.set(value);
+        });
+    assertThat(keyRef.get()).isEqualTo("User-Agent");
+    assertThat(valueRef.get()).matches("OTel OTLP Exporter Java/1\\..*");
+  }
+}

exporters/otlp/logs/src/main/java/io/opentelemetry/exporter/otlp/http/logs/OtlpHttpLogRecordExporterBuilder.java

@@ -10,6 +10,7 @@
 
 import io.opentelemetry.api.metrics.MeterProvider;
 import io.opentelemetry.exporter.internal.okhttp.OkHttpExporterBuilder;
+import io.opentelemetry.exporter.internal.otlp.OtlpUserAgent;
 import io.opentelemetry.exporter.internal.otlp.logs.LogsRequestMarshaler;
 import java.time.Duration;
 import java.util.concurrent.TimeUnit;
@@ -23,6 +24,7 @@ public final class OtlpHttpLogRecordExporterBuilder {
 
   OtlpHttpLogRecordExporterBuilder() {
     delegate = new OkHttpExporterBuilder<>("otlp", "log", DEFAULT_ENDPOINT);
+    OtlpUserAgent.addUserAgentHeader(delegate::addHeader);
   }
 
   /**

exporters/otlp/logs/src/main/java/io/opentelemetry/exporter/otlp/logs/OtlpGrpcLogRecordExporterBuilder.java

@@ -12,6 +12,7 @@
 import io.opentelemetry.api.metrics.MeterProvider;
 import io.opentelemetry.exporter.internal.grpc.GrpcExporter;
 import io.opentelemetry.exporter.internal.grpc.GrpcExporterBuilder;
+import io.opentelemetry.exporter.internal.otlp.OtlpUserAgent;
 import io.opentelemetry.exporter.internal.otlp.logs.LogsRequestMarshaler;
 import java.net.URI;
 import java.time.Duration;
@@ -41,6 +42,7 @@ public final class OtlpGrpcLogRecordExporterBuilder {
             DEFAULT_ENDPOINT,
             () -> MarshalerLogsServiceGrpc::newFutureStub,
             GRPC_ENDPOINT_PATH);
+    OtlpUserAgent.addUserAgentHeader(delegate::addHeader);
   }
 
   /**

exporters/otlp/testing-internal/src/main/java/io/opentelemetry/exporter/otlp/testing/internal/AbstractGrpcTelemetryExporterTest.java

@@ -216,6 +216,14 @@ void export() {
     assertThat(exporter.export(telemetry).join(10, TimeUnit.SECONDS).isSuccess()).isTrue();
     List<U> expectedResourceTelemetry = toProto(telemetry);
     assertThat(exportedResourceTelemetry).containsExactlyElementsOf(expectedResourceTelemetry);
+
+    // Assert request contains OTLP spec compliant User-Agent header
+    assertThat(httpRequests)
+        .singleElement()
+        .satisfies(
+            req -> {
+              assertThat(req.headers().get("User-Agent")).matches("OTel OTLP Exporter Java/1\\..*");
+            });
   }
 
   @Test

exporters/otlp/testing-internal/src/main/java/io/opentelemetry/exporter/otlp/testing/internal/ManagedChannelTelemetryExporterBuilder.java

@@ -10,6 +10,7 @@
 import io.grpc.ManagedChannel;
 import io.grpc.ManagedChannelBuilder;
 import io.opentelemetry.exporter.internal.grpc.ManagedChannelUtil;
+import io.opentelemetry.exporter.internal.otlp.OtlpUserAgent;
 import io.opentelemetry.exporter.internal.retry.RetryPolicy;
 import io.opentelemetry.sdk.common.CompletableResultCode;
 import java.net.URI;
@@ -51,6 +52,10 @@ public TelemetryExporterBuilder<T> setEndpoint(String endpoint) {
     if (!uri.getScheme().equals("https")) {
       channelBuilder.usePlaintext();
     }
+    // User-Agent can only be set at the channel level with upstream gRPC client. If a user wants
+    // the User-Agent to be spec compliant they must manually set the user agent when building
+    // their channel.
+    channelBuilder.userAgent(OtlpUserAgent.getUserAgent());
     return this;
   }