Convert reference application to use OpenTelemetry Java agent instead of manual SDK configuration

Co-authored-by: trask <[email protected]>

Author: Copilot

reference-application/Dockerfile

@@ -2,11 +2,12 @@ FROM openjdk:17-jdk-slim
 
 WORKDIR /app
 
-# Copy the JAR file
-COPY build/libs/*.jar app.jar
+# Copy the JAR file and agent
+COPY build/libs/app.jar /app.jar
+COPY build/agent/opentelemetry-javaagent.jar /opentelemetry-javaagent.jar
 
 # Expose the port
 EXPOSE 8080
 
-# Run the application
-ENTRYPOINT ["java", "-jar", "app.jar"]
+# Run the application with the Java agent
+ENTRYPOINT ["java", "-javaagent:/opentelemetry-javaagent.jar", "-jar", "/app.jar"]

reference-application/README.md

@@ -15,7 +15,7 @@ This application showcases:
 
 ## Application Overview
 
-The reference application is a dice rolling service that simulates various scenarios to demonstrate OpenTelemetry capabilities:
+The reference application is a dice rolling service that demonstrates OpenTelemetry capabilities using the **OpenTelemetry Java Agent** for automatic instrumentation and manual instrumentation examples:
 
 ### Endpoints
 
@@ -45,8 +45,11 @@ The reference application is a dice rolling service that simulates various scena
 ### Running with Console Output
 
 ```shell
-# Build and run with console logging
-../gradlew bootRun
+# Build the application with the Java agent
+../gradlew bootJar
+
+# Run with the Java agent for automatic instrumentation
+java -javaagent:build/agent/opentelemetry-javaagent.jar -jar build/libs/app.jar
 ```
 
 Then test the endpoints:
@@ -59,6 +62,9 @@ curl http://localhost:8080/fibonacci?n=10
 ### Running with OpenTelemetry Collector
 
 ```shell
+# Build the application
+../gradlew bootJar
+
 # Start the collector and application
 docker-compose up --build
 ```
@@ -84,13 +90,9 @@ export OTEL_METRICS_EXPORTER=otlp
 export OTEL_LOGS_EXPORTER=otlp
 ```
 
-### Programmatic Configuration
+### Java Agent Configuration
 
-See `src/main/java/io/opentelemetry/example/config/` for examples of:
-- Manual SDK initialization
-- Custom span processors and exporters
-- Resource configuration
-- Sampling configuration
+The application uses the OpenTelemetry Java Agent which automatically configures instrumentation based on environment variables and system properties. All standard OpenTelemetry configuration options are supported.
 
 ### Declarative Configuration
 

reference-application/build.gradle.kts

@@ -1,9 +1,9 @@
 import org.springframework.boot.gradle.plugin.SpringBootPlugin
+import org.springframework.boot.gradle.tasks.bundling.BootJar
 
 plugins {
     id("java")
     id("org.springframework.boot") version "3.5.6"
-    id("io.spring.dependency-management") version "1.1.6"
 }
 
 val moduleName by extra { "io.opentelemetry.examples.reference-application" }
@@ -12,35 +12,41 @@ repositories {
     mavenCentral()
 }
 
+val agent = configurations.create("agent")
+
 dependencies {
     implementation(platform(SpringBootPlugin.BOM_COORDINATES))
-    implementation(platform("io.opentelemetry.instrumentation:opentelemetry-instrumentation-bom:2.20.1"))
+    implementation("io.opentelemetry:opentelemetry-api")
 
     // Spring Boot
     implementation("org.springframework.boot:spring-boot-starter-web")
     implementation("org.springframework.boot:spring-boot-starter-actuator")
 
-    // OpenTelemetry SDK and API
-    implementation("io.opentelemetry:opentelemetry-api")
-    implementation("io.opentelemetry:opentelemetry-sdk")
-    implementation("io.opentelemetry:opentelemetry-sdk-extension-autoconfigure")
-    
-    // OpenTelemetry Exporters
-    implementation("io.opentelemetry:opentelemetry-exporter-otlp")
-    implementation("io.opentelemetry:opentelemetry-exporter-logging")
-    implementation("io.opentelemetry:opentelemetry-exporter-prometheus")
-    
-    // OpenTelemetry Instrumentation - use manual configuration instead of starter
+    // OpenTelemetry Instrumentation - use logback appender for logs
     implementation("io.opentelemetry.instrumentation:opentelemetry-logback-appender-1.0")
 
     // Micrometer for additional metrics
     implementation("io.micrometer:micrometer-registry-prometheus")
 
+    // Java agent
+    agent("io.opentelemetry.javaagent:opentelemetry-javaagent:2.20.1")
+    
     // Testing
     testImplementation("org.springframework.boot:spring-boot-starter-test")
     testImplementation("io.opentelemetry:opentelemetry-sdk-testing")
 }
 
+val copyAgent = tasks.register<Copy>("copyAgent") {
+    from(agent.singleFile)
+    into(layout.buildDirectory.dir("agent"))
+    rename("opentelemetry-javaagent-.*\\.jar", "opentelemetry-javaagent.jar")
+}
+
+tasks.named<BootJar>("bootJar") {
+    dependsOn(copyAgent)
+    archiveFileName = "app.jar"
+}
+
 tasks.withType<Test> {
     useJUnitPlatform()
 }

reference-application/src/main/java/io/opentelemetry/example/ReferenceApplication.java

@@ -3,6 +3,8 @@
 import io.micrometer.core.instrument.Counter;
 import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.Timer;
+import io.opentelemetry.api.GlobalOpenTelemetry;
+import io.opentelemetry.api.OpenTelemetry;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.context.annotation.Bean;
@@ -14,6 +16,11 @@ public static void main(String[] args) {
     SpringApplication.run(ReferenceApplication.class, args);
   }
 
+  @Bean
+  public OpenTelemetry openTelemetry() {
+    return GlobalOpenTelemetry.get();
+  }
+
   @Bean
   public Counter diceRollCounter(MeterRegistry meterRegistry) {
     return Counter.builder("dice_rolls_total")