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System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) · 강의

분산 추적 작동 방식

서비스 경계를 넘어 컨텍스트가 전파되는 방식을 포함하여 분산 추적의 작동 원리를 살펴봅니다. 여러 마이크로서비스를 거치는 요청을 추적하는 방법을 알아봅니다.

분산 추적 작동 방식은(는) CoddyKit의 무료 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 강의입니다. 이것은 4개 중 2번째 강의입니다. 아래에서 전체 강의를 무료로 읽을 수 있으며, 내장 코드 에디터와 24/7 AI 튜터와 함께 브라우저에서 직접 실습할 수 있습니다. 이 강의는 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 학습 경로의 일부이며, 진행 상황이 웹과 CoddyKit 앱에 동기화됩니다. System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 강의에는 총 4개의 강의가 포함되어 있습니다.

이 강의의 일부는 아직 번역되지 않았으며 영어로 표시됩니다.

What is Context Propagation?

Imagine a request traveling through many services. How do we know it's all part of the same original operation? This is where context propagation comes in.

It's the mechanism that ensures unique identifiers (like a Trace ID) and other relevant information follow a request as it moves between different services or components.

Without it, each service would start a "new" trace, making it impossible to see the full end-to-end journey.

What is Trace Context?

The "context" being propagated isn't just a single ID. It's a small bundle of information called the trace context.

  • Trace ID: The unique identifier for the entire request journey.
  • Span ID: The ID of the current operation within the trace.
  • Parent Span ID: The ID of the operation that called the current one.
  • Trace Flags: Information like whether the trace is sampled (should be recorded).

This context is crucial for linking operations together.

Context in HTTP Headers

When services communicate over HTTP, the trace context is typically propagated using special HTTP headers.

The calling service injects the context into the outgoing request's headers. The receiving service then extracts this context from the incoming request's headers.

Common header formats include W3C Trace Context (traceparent, tracestate) and B3 Propagation headers.

Tracing a Service Call

Let's trace a simple request:

  1. User makes a request to Service A.
  2. Service A starts a new trace and span.
  3. Service A calls Service B, injecting its current trace context into the HTTP headers.
  4. Service B receives the request, extracts the context, and creates a new span linked to Service A's span.
  5. Service B may then call Service C, propagating the context further.

This chain allows us to see the full path.

Injecting Context into Requests

Imagine we have a TraceContext object. Before making an HTTP call, we'd inject its details into the request headers. This example simulates adding a traceparent header.

Try running this example:

public class ClientService {
  public static void main(String[] args) {
    String traceId = "a1b2c3d4e5f6g7h8";
    String spanId = "i9j0k1l2m3n4o5p6";
    String traceparentHeader = String.format("00-%s-%s-01", traceId, spanId);

    System.out.println("--- Client Service ---");
    System.out.println("Preparing outgoing request.");
    System.out.println("Injecting trace context into header:");
    System.out.println("  traceparent: " + traceparentHeader);
    System.out.println("Making call to Service B...");
  }
}

Extracting Context from Requests

When Service B receives the request, it looks for these special headers. It then extracts the trace context to understand its place in the overall operation.

This example simulates extracting the traceparent header.

Try running this example:

public class ServerService {
  public static void main(String[] args) {
    // Simulate an incoming request header
    String incomingTraceparent = "00-a1b2c3d4e5f6g7h8-i9j0k1l2m3n4o5p6-01";

    System.out.println("--- Server Service ---");
    System.out.println("Received incoming request.");
    System.out.println("Extracting trace context from header:");
    System.out.println("  traceparent: " + incomingTraceparent);

    // Parse the header (simplified)
    String[] parts = incomingTraceparent.split("-");
    if (parts.length == 4) {
      System.out.println("  Extracted Trace ID: " + parts[1]);
      System.out.println("  Extracted Parent Span ID: " + parts[2]);
    } else {
      System.out.println("  Could not parse traceparent header.");
    }
  }
}

Automated Instrumentation

Manually injecting and extracting context for every call would be tedious and error-prone. This is where instrumentation libraries come in.

These libraries, often part of an observability framework like OpenTelemetry, automatically:

  • Generate new trace and span IDs.
  • Inject context into outgoing requests (e.g., HTTP clients).
  • Extract context from incoming requests (e.g., HTTP servers).
  • Create new child spans linked to the parent.

They handle the heavy lifting for you!

Beyond HTTP: Other Protocols

While HTTP headers are common, context propagation isn't limited to them. Tracing needs to work across various communication methods:

  • Message Queues: Context can be added as metadata to messages (e.g., Kafka headers, RabbitMQ properties).
  • gRPC: Context is propagated via gRPC metadata.
  • Databases: Sometimes, context can be passed within a database transaction or even as comments in queries for advanced scenarios.

The principle remains the same: pass the trace context along.

Full Request Journey

With proper context propagation, a distributed tracing system can reconstruct the entire journey of a request.

This allows you to visualize:

  • Which services were involved.
  • The order of operations.
  • How long each service took.
  • Where errors occurred.

This end-to-end visibility is invaluable for debugging and performance optimization in complex microservice architectures.

Propagating the Context

You're building a microservice application. Service A calls Service B, and you want to ensure the trace context is correctly passed between them to link their operations.

Recap: How Tracing Works

In this lesson, we explored the core mechanism behind distributed tracing: context propagation.

  • Trace context (IDs, flags) is passed between services.
  • HTTP headers are a common way to propagate context.
  • Instrumentation libraries automate the injection and extraction of context.
  • This allows for end-to-end visibility of requests across distributed systems.

Understanding this process is key to leveraging distributed tracing effectively!

자주 묻는 질문

“분산 추적 작동 방식” 강의는 무료인가요?

네 — “분산 추적 작동 방식” 전체 내용을 이 웹사이트에서 무료로 읽을 수 있습니다. 인터랙티브하게 실습하려면(내장 코드 에디터와 24/7 AI 튜터), CoddyKit PRO로 업그레이드하면 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 강의 전체를 잠금 해제할 수 있습니다. System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 강의에는 총 4개의 강의가 포함되어 있습니다.

“분산 추적 작동 방식”에서 뭘 배우나요?

서비스 경계를 넘어 컨텍스트가 전파되는 방식을 포함하여 분산 추적의 작동 원리를 살펴봅니다. 여러 마이크로서비스를 거치는 요청을 추적하는 방법을 알아봅니다. 브라우저에서 직접 실행하는 실습 코드로 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry)을(를) 배우며, 24/7 AI 튜터가 강의를 진행하면서 질문에 답변해줍니다.

System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry)을(를) 시작하는 데 경험이 필요한가요?

사전 경험은 필요하지 않습니다. CoddyKit의 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry)은(는) 초급자부터 고급 학습자까지를 위해 구성되어 있으므로, 여기서 시작하거나 처음부터 시작할 수 있으며 자신의 속도대로 진행할 수 있습니다. 이것은 4개 중 2번째 강의입니다.

“분산 추적 작동 방식” 강의는 얼마나 걸리나요?

대부분의 CoddyKit 강의는 약 5~10분이 소요됩니다. 각 강의는 간결하고 인터랙티브하여 꾸준한 진행이 가능하며, 웹과 앱에서 중단한 부분부터 바로 시작할 수 있습니다.

이 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 강의에서 코드를 작성하고 실행할 수 있나요?

네. 모든 System Observability: Logging, Metrics & Tracing (ELK + OpenTelemetry) 강의에는 내장 코드 에디터가 포함되어 있으므로, 브라우저에서 바로 실제 코드를 작성하고 실행한 후 즉시 AI 피드백을 받을 수 있습니다 — 로컬 설정이 필요 없습니다.

이 강의의 모든 강의

  1. 추적 스팬과 ID 이해
  2. 분산 추적 작동 방식
  3. 추적과 로깅 및 지표 비교
  4. 트레이스를 위한 샘플링 전략
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