Application Real-Time Monitoring Service：通過OpenTelemetry Java SDK為調用鏈增加自訂埋點

@RestController
@RequestMapping("/ot")
public class OpenTelemetryController {
    private Tracer tracer;
    private ScheduledExecutorService ses = Executors.newSingleThreadScheduledExecutor();
    @PostConstruct
    public void init() {
	    OpenTelemetrySdk.builder()
			.setPropagators(ContextPropagators.create(W3CTraceContextPropagator.getInstance()))
			.buildAndRegisterGlobal();
		tracer = GlobalOpenTelemetry.get().getTracer("manual-sdk", "1.0.0");
        ses.scheduleAtFixedRate(new Runnable() {
            @Override
            public void run() {
                Span span = tracer.spanBuilder("schedule")
                        .setAttribute("schedule.time", System.currentTimeMillis())
                        .startSpan();
                try (Scope scope = span.makeCurrent()) {
                    System.out.println("scheduled!");
                    Thread.sleep(500L);
                    span.setAttribute("schedule.success", true);
                    System.out.println(Span.current().getSpanContext().getTraceId()); // 擷取 TraceId
                } catch (Throwable t) {
                    span.setStatus(StatusCode.ERROR, t.getMessage());
                } finally {
                    span.end();
                }
            }
        }, 10, 30, TimeUnit.SECONDS);
    }
    @ResponseBody
    @RequestMapping("/parent")
    public String parent() {
        Span span = tracer.spanBuilder("parent").setSpanKind(SpanKind.SERVER).startSpan();
        try (Scope scope = span.makeCurrent()) {
            // 使用Baggage透傳業務自訂標籤
            Baggage baggage =  Baggage.current().toBuilder()
                    .put("user.id", "1")
                    .put("user.name", "name")
                    .build();
            try (Scope baggageScope = baggage.storeInContext(Context.current()).makeCurrent()) {
                child();
            }
            span.setAttribute("http.method", "GET");
            span.setAttribute("http.uri", "/parent");
        } finally {
            span.end();
        }
        return "parent";
    }
    private void child() {
        Span span = tracer.spanBuilder("child").startSpan();
        try (Scope scope = span.makeCurrent()) {
            System.out.println("current traceId = " + Span.current().getSpanContext().getTraceId());
            System.out.println("userId in baggage = " + Baggage.current().getEntryValue("user.id"));
            Thread.sleep(1000);
        } catch (Throwable e) {
            span.setStatus(StatusCode.ERROR, e.getMessage());
        } finally {
            span.end();
        }
    }
}