README.md

Exercise 9 - Distributed Tracing

The sample guestbook application shows how a Spring Java application can be configured to collect trace spans using Zipkin or Jaeger.

Although Istio proxies are able to automatically send spans, it needs help from the application to tie together the entire trace. To do this applications need to propagate the appropriate HTTP headers so that when the proxies send span information to Zipkin or Jaeger, the spans can be correlated correctly into a single trace.

To do this the guestbook application collects and propagate the following headers from the incoming request to any outgoing requests:

• x-request-id
• x-b3-traceid
• x-b3-spanid
• x-b3-parentspanid
• x-b3-sampled
• x-b3-flags
• x-ot-span-context

This is done with the Spring Istio Support written by Ray Tsang:

https://github.com/retroryan/istio-by-example-java/tree/master/spring-boot-example/spring-istio-support/src/main/java/com/example/istio

View Guestbook Traces

Generate a small load to the application.

while sleep 0.5; do curl http://$INGRESS_IP/echo/universe -A mobile; done

Jaeger

Establish port forwarding from local port 16686 to the Jaeger instance:

kubectl port-forward -n istio-system \
$(kubectl get pod -n istio-system -l app=jaeger -o \
jsonpath='{.items[0].metadata.name}') 16686:16686 &

Browse to http://localhost:16686

Continue to Exercise 10 - Request Routing and Canary Testing