// Create Tracer
Tracer tracer = openTelemetry.getTracer("order-service");

// Create Span
Span span = tracer.spanBuilder("processOrder").startSpan();
try (Scope scope = span.makeCurrent()) {
    span.setAttribute("order.id", orderId);
    // Business logic
} finally {
    span.end();
}

# otel-collector.yaml
receivers:
  otlp:
    protocols:
      grpc:
        endpoint: 0.0.0.0:4317
      http:
        endpoint: 0.0.0.0:4318

processors:
  batch:
    timeout: 1s
    send_batch_size: 1024
  memory_limiter:
    limit_mib: 512

exporters:
  otlp:
    endpoint: "tempo:4317"
    tls:
      insecure: true
  prometheus:
    endpoint: "0.0.0.0:8889"
  loki:
    endpoint: "http://loki:3100/loki/api/v1/push"

service:
  pipelines:
    traces:
      receivers: [otlp]
      processors: [batch, memory_limiter]
      exporters: [otlp]
    metrics:
      receivers: [otlp]
      processors: [batch]
      exporters: [prometheus]
    logs:
      receivers: [otlp]
      processors: [batch]
      exporters: [loki]

// build.gradle.kts
dependencies {
    // Tracing
    implementation("io.micrometer:micrometer-tracing-bridge-otel")
    implementation("io.opentelemetry:opentelemetry-exporter-otlp")

    // Metrics
    implementation("io.micrometer:micrometer-registry-otlp")

    // Auto instrumentation (optional)
    runtimeOnly("io.opentelemetry.instrumentation:opentelemetry-spring-boot-starter")
}

spring:
  application:
    name: order-service

management:
  otlp:
    tracing:
      endpoint: http://otel-collector:4318/v1/traces
    metrics:
      export:
        endpoint: http://otel-collector:4318/v1/metrics
        step: 30s
  tracing:
    sampling:
      probability: 0.1  # 10% sampling

logging:
  pattern:
    level: "%5p [${spring.application.name},%X{traceId:-},%X{spanId:-}]"

@Service
@RequiredArgsConstructor
public class OrderService {
    private final Tracer tracer;
    private final MeterRegistry meterRegistry;

    public Order createOrder(OrderRequest request) {
        // Create Span
        Span span = tracer.nextSpan()
            .name("createOrder")
            .tag("order.type", request.getType())
            .start();

        try (Tracer.SpanInScope ws = tracer.withSpan(span)) {
            // Record metric
            Timer.Sample sample = Timer.start(meterRegistry);

            Order order = processOrder(request);

            sample.stop(Timer.builder("order.creation.time")
                .tag("type", request.getType())
                .register(meterRegistry));

            span.event("Order created successfully");
            return order;

        } catch (Exception e) {
            span.error(e);
            throw e;
        } finally {
            span.end();
        }
    }
}

java -javaagent:opentelemetry-javaagent.jar \
     -Dotel.service.name=order-service \
     -Dotel.exporter.otlp.endpoint=http://otel-collector:4317 \
     -Dotel.traces.sampler=parentbased_traceidratio \
     -Dotel.traces.sampler.arg=0.1 \
     -jar app.jar

FROM eclipse-temurin:17-jre

ADD https://github.com/open-telemetry/opentelemetry-java-instrumentation/releases/latest/download/opentelemetry-javaagent.jar /app/opentelemetry-javaagent.jar

ENV JAVA_TOOL_OPTIONS="-javaagent:/app/opentelemetry-javaagent.jar"
ENV OTEL_SERVICE_NAME="order-service"
ENV OTEL_EXPORTER_OTLP_ENDPOINT="http://otel-collector:4317"

COPY app.jar /app/app.jar
CMD ["java", "-jar", "/app/app.jar"]