K8s em Exemplos: Rastreamento Distribuído

Rastreamento distribuído segue requisições enquanto fluem através de microsserviços. Cada serviço adiciona spans a um trace, mostrando timing e relacionamentos. Baseado no paper Dapper do Google, ferramentas como Jaeger e Zipkin coletam traces. Use para: debugging de latência, entender dependências, encontrar gargalos.

terminal

Quick start: faça deploy do Jaeger para coleta e visualização de traces. Para produção, use o Jaeger Operator ou chart Helm com storage persistente. A imagem all-in-one é adequada para desenvolvimento.

$ kubectl apply -n tracing --create-namespace -f https://github.com/jaegertracing/jaeger-kubernetes/raw/main/all-in-one/jaeger-all-in-one-template.yml
namespace/tracing created
deployment.apps/jaeger created
service/jaeger-query created
service/jaeger-collector created

otel-sidecar.yaml

O sidecar OpenTelemetry Collector recebe traces da aplicação e exporta para backends (Jaeger, Zipkin, Tempo). Apps enviam traces para localhost; o sidecar lida com batching, retry e exportação.

apiVersion: v1
kind: Pod
metadata:
  name: traced-app
spec:
  containers:
    - name: app
      image: my-app:v1
      env:
        - name: OTEL_EXPORTER_OTLP_ENDPOINT
          value: "http://localhost:4317"
        - name: OTEL_SERVICE_NAME
          value: "my-app"
    - name: otel-collector
      image: otel/opentelemetry-collector:0.91.0
      args: ["--config=/etc/otel/config.yaml"]
      ports:
        - containerPort: 4317
        - containerPort: 4318
      volumeMounts:
        - name: otel-config
          mountPath: /etc/otel
  volumes:
    - name: otel-config
      configMap:
        name: otel-collector-config

otel-collector-config.yaml

Config do Collector define receivers (como traces chegam), processors (batching, filtragem), e exporters (para onde traces vão). Esta config recebe traces OTLP e exporta para Jaeger.

apiVersion: v1
kind: ConfigMap
metadata:
  name: otel-collector-config
data:
  config.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
    exporters:
      otlp:
        endpoint: "jaeger-collector.tracing.svc:4317"
        tls:
          insecure: true
    service:
      pipelines:
        traces:
          receivers: [otlp]
          processors: [batch]
          exporters: [otlp]

trace-propagation.yaml

Propagação de contexto de trace passa IDs de trace entre serviços via headers HTTP. O padrão W3C Trace Context usa headers traceparent e tracestate. Configure apps para extrair contexto de entrada e injetar em requisições de saída.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: order-service
spec:
  template:
    spec:
      containers:
        - name: order
          image: order-service:v1
          env:
            - name: OTEL_SERVICE_NAME
              value: "order-service"
            - name: OTEL_PROPAGATORS
              value: "tracecontext,baggage"
            - name: OTEL_EXPORTER_OTLP_ENDPOINT
              value: "http://otel-collector.tracing.svc:4317"
            - name: OTEL_RESOURCE_ATTRIBUTES
              value: "k8s.namespace.name=$(POD_NAMESPACE),k8s.pod.name=$(POD_NAME)"
            - name: POD_NAMESPACE
              valueFrom:
                fieldRef:
                  fieldPath: metadata.namespace
            - name: POD_NAME
              valueFrom:
                fieldRef:
                  fieldPath: metadata.name

jaeger-deployment.yaml

Deploy Jaeger all-in-one para desenvolvimento. Inclui collector, query UI e storage em memória. Para produção, use componentes separados com storage persistente (Elasticsearch, Cassandra).

apiVersion: apps/v1
kind: Deployment
metadata:
  name: jaeger
  namespace: tracing
spec:
  selector:
    matchLabels:
      app: jaeger
  template:
    metadata:
      labels:
        app: jaeger
    spec:
      containers:
        - name: jaeger
          image: jaegertracing/all-in-one:1.53
          ports:
            - containerPort: 16686
              name: ui
            - containerPort: 4317
              name: otlp-grpc
            - containerPort: 4318
              name: otlp-http
          env:
            - name: COLLECTOR_OTLP_ENABLED
              value: "true"
---
apiVersion: v1
kind: Service
metadata:
  name: jaeger-collector
  namespace: tracing
spec:
  selector:
    app: jaeger
  ports:
    - port: 4317
      name: otlp-grpc
    - port: 16686
      name: ui

sampling-config.yaml

Sampling reduz volume de traces em sistemas de alto tráfego. Head-based sampling decide no início do trace; tail-based faz amostragem após ver o trace completo. Configure ratio (0.1 = 10%) ou use sampling adaptativo baseado no tráfego.

apiVersion: v1
kind: ConfigMap
metadata:
  name: otel-sampling-config
data:
  config.yaml: |
    receivers:
      otlp:
        protocols:
          grpc:
            endpoint: 0.0.0.0:4317
    processors:
      batch: {}
      probabilistic_sampler:
        sampling_percentage: 10
      tail_sampling:
        decision_wait: 10s
        policies:
          - name: errors
            type: status_code
            status_code: {status_codes: [ERROR]}
          - name: slow-traces
            type: latency
            latency: {threshold_ms: 1000}
    exporters:
      otlp:
        endpoint: "jaeger-collector:4317"
    service:
      pipelines:
        traces:
          receivers: [otlp]
          processors: [tail_sampling, batch]
          exporters: [otlp]

terminal

Acesse a UI do Jaeger para buscar traces por serviço, operação, tags ou duração. Visualize timelines de trace mostrando relacionamentos de spans, identifique serviços lentos e analise caminhos de erro.

$ kubectl port-forward svc/jaeger-collector 16686:16686 -n tracing &

$ curl localhost:16686/api/services | jq '.data'
["order-service", "payment-service", "inventory-service"]

$ curl "localhost:16686/api/traces?service=order-service&limit=10" | jq '.data[0]'
{
  "traceID": "abc123...",
  "spans": [
    {"operationName": "POST /orders", "duration": 245000},
    {"operationName": "check-inventory", "duration": 89000},
    {"operationName": "process-payment", "duration": 156000}
  ]
}

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