declarative config: set distro + user-agent (#1050)

* add distro resource attributes for dc

* add some tests for distro resource

* start implementation of custom user-agent

* finish work on user-agent

* cleanup

* remove duplication

* fix things

Author: SylvainJuge

custom/build.gradle.kts

@@ -23,8 +23,10 @@ dependencies {
   }
 
   compileOnly("io.opentelemetry:opentelemetry-sdk")
+  compileOnly("io.opentelemetry:opentelemetry-api-incubator")
   compileOnly("io.opentelemetry:opentelemetry-exporter-otlp")
   compileOnly("io.opentelemetry:opentelemetry-sdk-extension-autoconfigure-spi")
+  compileOnly("io.opentelemetry:opentelemetry-sdk-extension-incubator")
   compileOnly("io.opentelemetry.javaagent:opentelemetry-javaagent-extension-api")
   compileOnly("io.opentelemetry.javaagent:opentelemetry-javaagent-tooling")
   compileOnly(libs.bundles.semconv)
@@ -54,8 +56,10 @@ dependencies {
   // test dependencies
   testImplementation(project(":testing-common"))
   testImplementation("io.opentelemetry:opentelemetry-sdk")
+  testImplementation("io.opentelemetry:opentelemetry-api-incubator")
   testImplementation("io.opentelemetry:opentelemetry-sdk-extension-autoconfigure")
   testImplementation("io.opentelemetry:opentelemetry-sdk-extension-autoconfigure-spi")
+  testImplementation("io.opentelemetry:opentelemetry-sdk-extension-incubator")
   testImplementation("io.opentelemetry:opentelemetry-exporter-otlp")
   testImplementation("io.opentelemetry.javaagent:opentelemetry-javaagent-tooling") {
     //The following dependency isn't actually needed, but breaks the classpath when testing with Java 8
@@ -67,6 +71,7 @@ dependencies {
   testImplementation("io.opentelemetry:opentelemetry-sdk-testing")
   testImplementation(libs.freemarker)
   testImplementation(libs.wiremockjre8)
+  testImplementation(libs.jsonunitassertj)
 }
 
 tasks {

custom/src/main/java/co/elastic/otel/ElasticDistroResource.java

@@ -0,0 +1,48 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package co.elastic.otel;
+
+import io.opentelemetry.api.common.Attributes;
+import io.opentelemetry.javaagent.tooling.AgentVersion;
+import io.opentelemetry.sdk.resources.Resource;
+import io.opentelemetry.semconv.incubating.TelemetryIncubatingAttributes;
+
+public class ElasticDistroResource {
+
+  private ElasticDistroResource() {}
+
+  public static Resource get() {
+    if (AgentVersion.VERSION == null) {
+      return Resource.empty();
+    }
+    try {
+      Class.forName("co.elastic.otel.agent.ElasticAgent");
+    } catch (ClassNotFoundException e) {
+      // this means that we are running as an extension of the vanilla agent
+      // and not as distro.
+      return Resource.empty();
+    }
+    return Resource.create(
+        Attributes.of(
+            TelemetryIncubatingAttributes.TELEMETRY_DISTRO_NAME,
+            "elastic",
+            TelemetryIncubatingAttributes.TELEMETRY_DISTRO_VERSION,
+            AgentVersion.VERSION));
+  }
+}

custom/src/main/java/co/elastic/otel/ElasticDistroResourceProvider.java

@@ -19,33 +19,19 @@
 package co.elastic.otel;
 
 import com.google.auto.service.AutoService;
-import io.opentelemetry.api.common.Attributes;
-import io.opentelemetry.javaagent.tooling.AgentVersion;
 import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
 import io.opentelemetry.sdk.autoconfigure.spi.ResourceProvider;
 import io.opentelemetry.sdk.resources.Resource;
-import io.opentelemetry.semconv.incubating.TelemetryIncubatingAttributes;
 
+/**
+ * Provides {@code telemetry.distro.name} and {@code telemetry.distro.version} resource attributes
+ * for automatic configuration
+ */
 @AutoService(ResourceProvider.class)
 public class ElasticDistroResourceProvider implements ResourceProvider {
 
   @Override
   public Resource createResource(ConfigProperties configProperties) {
-    if (AgentVersion.VERSION == null) {
-      return Resource.empty();
-    }
-    try {
-      Class.forName("co.elastic.otel.agent.ElasticAgent");
-    } catch (ClassNotFoundException e) {
-      // this means that we are running as an extension of the vanilla agent
-      // and not as distro.
-      return Resource.empty();
-    }
-    return Resource.create(
-        Attributes.of(
-            TelemetryIncubatingAttributes.TELEMETRY_DISTRO_NAME,
-            "elastic",
-            TelemetryIncubatingAttributes.TELEMETRY_DISTRO_VERSION,
-            AgentVersion.VERSION));
+    return ElasticDistroResource.get();
   }
 }

custom/src/main/java/co/elastic/otel/ElasticUserAgentHeader.java

@@ -29,41 +29,42 @@
 import io.opentelemetry.sdk.metrics.export.MetricExporter;
 import io.opentelemetry.sdk.trace.export.SpanExporter;
 
+/** set User-Agent for automatic configuration */
 public class ElasticUserAgentHeader {
 
-  private static final String HEADER_NAME = "User-Agent";
-  private static final String GRPC_VALUE = "elastic-otlp-grpc-java/" + AgentVersion.VERSION;
-  private static final String HTTP_VALUE = "elastic-otlp-http-java/" + AgentVersion.VERSION;
+  public static final String HEADER_NAME = "User-Agent";
+  public static final String OTLP_GRPC = "elastic-otlp-grpc-java/" + AgentVersion.VERSION;
+  public static final String OTLP_HTTP = "elastic-otlp-http-java/" + AgentVersion.VERSION;
 
   public static SpanExporter configureIfPossible(SpanExporter spanExporter) {
     if (spanExporter instanceof OtlpGrpcSpanExporter) {
       return ((OtlpGrpcSpanExporter) spanExporter)
-          .toBuilder().addHeader(HEADER_NAME, GRPC_VALUE).build();
+          .toBuilder().addHeader(HEADER_NAME, OTLP_GRPC).build();
     } else if (spanExporter instanceof OtlpHttpSpanExporter) {
       return ((OtlpHttpSpanExporter) spanExporter)
-          .toBuilder().addHeader(HEADER_NAME, HTTP_VALUE).build();
+          .toBuilder().addHeader(HEADER_NAME, OTLP_HTTP).build();
     }
     return spanExporter;
   }
 
   public static MetricExporter configureIfPossible(MetricExporter metricExporter) {
     if (metricExporter instanceof OtlpGrpcMetricExporter) {
       return ((OtlpGrpcMetricExporter) metricExporter)
-          .toBuilder().addHeader(HEADER_NAME, GRPC_VALUE).build();
+          .toBuilder().addHeader(HEADER_NAME, OTLP_GRPC).build();
     } else if (metricExporter instanceof OtlpHttpMetricExporter) {
       return ((OtlpHttpMetricExporter) metricExporter)
-          .toBuilder().addHeader(HEADER_NAME, HTTP_VALUE).build();
+          .toBuilder().addHeader(HEADER_NAME, OTLP_HTTP).build();
     }
     return metricExporter;
   }
 
   public static LogRecordExporter configureIfPossible(LogRecordExporter logExporter) {
     if (logExporter instanceof OtlpGrpcLogRecordExporter) {
       return ((OtlpGrpcLogRecordExporter) logExporter)
-          .toBuilder().addHeader(HEADER_NAME, GRPC_VALUE).build();
+          .toBuilder().addHeader(HEADER_NAME, OTLP_GRPC).build();
     } else if (logExporter instanceof OtlpHttpLogRecordExporter) {
       return ((OtlpHttpLogRecordExporter) logExporter)
-          .toBuilder().addHeader(HEADER_NAME, HTTP_VALUE).build();
+          .toBuilder().addHeader(HEADER_NAME, OTLP_HTTP).build();
     }
     return logExporter;
   }