A recursing microservice to demonstrate OpenTracing with one-only service and jaegertracing/all-in-one or Istio

This demonstration is based on a simple docker-compose.yaml file. The associated resources are all available in the project directory and on docker hub gregoryguillou/recursed.

For a quick start, you can download the docker-compose.yml file and run docker-compose up. You should be able:

• To run a test with curl and the command below:

curl -v 0.0.0.0:8000/ -d '{"value": 6}' \
  -XPOST -H 'Content-Type: application/json'

• To access UI, open this url

If you want to know more, visit the associated article on my blog

The -istio flag allows to use recursed with the Istio Envoy-based tracing that relies on B3/Zipkin headers as well as the x-request-id header. Once you've installed Istio with Jaeger or Zipkin, deploy the recursed-istio.yml manifest. It includes a sample gateway, a virtual service, a service and a deployment for a whole test.

• To run a command with curl, get the gataway URL which depends on your Kubernetes setup and the service named istio-ingressgateway located in the istio-system namespace. For instance on AWS, assuming the service relies on a loadbalancer, you should get it with the command below. Adapt the --ouputor -o to your requirements:

kubectl get svc -n istio-system istio-ingressgateway \
  -o jsonpath='{.status.loadBalancer.ingress[0].hostname}'
  
export GW=$(kubectl get svc -n istio-system istio-ingressgateway \
  -o jsonpath='{.status.loadBalancer.ingress[0].hostname}')

• You should be able to run a curl command like the one below:

curl -v $GW/ -d '{"value": 6}' \
  -X POST  -H 'Content-Type: application/json'

• Connect to your jaeger instance with a port-forward command and opening with your browser on this url:

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

Note: In order for Jaeger to work, you should first have a service and a pod running with Istio so that Pilot can be started and configure the OpenTracing service based on the feedback it gets. You will not be able to access Jaeger and will get errors like the ones below before you start an application in Istio:

[2023-06-06 07:14:07.567][13][warning][config] [bazel-out/k8-opt/bin/external/envoy/source/common/config/_virtual_includes/grpc_stream_lib/common/config/grpc_stream.h:86] gRPC config stream closed: 14, upstream connect error or disconnect/reset before headers. reset reason: connection failure
2023-06-06T07:14:09.419199Z	info	Envoy proxy is NOT ready: config not received from Pilot (is Pilot running?): cds updates: 0 successful, 0 rejected; lds updates: 0 successful, 0 rejected
[...]