Developing on Cloud Nine

We all know the advantages of developing locally. It's fast, it's easy, it's free. You can easily find the running apps and their logs, and debugging is a breeze. But the local development environment is not realistic because dependencies cannot be emulated like they can in the real world. There can be small or large differences from production environments. Additionally, all services have to be set up locally and kept in sync during production. This can potentially be a big burden for developers to handle as applications scale. Some services are impossible to run locally, like various types of data stores and queues provided as managed services by cloud vendors. Mocking or replicating cloud services or managed services in your local environment simply no longer translates to the real environment upon which your application will run during production. This means you are missing the chance to find potential sources of failures and not testing your applications in a realistic manner.

Using Helm & Kubectl Directly

Deploy

• Deploy (in this case to local k8s cluster - docker-desktop): [greeting] helm upgrade --install greeting ./helm
• Check rollout status: kubectl rollout status deployment greeting
• Browse service: http://localhost:8088/greet/hello

Develop

• Change greeting in GreetingController to "Shalom"
• Build the app: [greeting] ./gradlew build -x check
• Build docker images (1.0.0): [greeting] docker build -t k8s-demo/greeting:1.0.0 .
• Deploy and check rollout status
• Tail logs using kubetail: kt greeting
• Browse service: http://localhost:8088/greet/hello

Debug

• Use debug flag & reduce # of replicas to 1: [greeting] helm upgrade --install greeting ./helm --set replicas=1 --set debug=true
• Run kubectl rollout status deployment greeting
• port-forward local port 5005 to pod's 5005: kubectl port-forward greeting-<pod-hash> 5005
• Launch debugger and put a breakpoint in the GreetingController, and hit http://localhost:8088/greet/hello
• Clean up: revert replicas and debug: helm upgrade --install --reset-values greeting ./helm

Skaffold

Develop

• Run skaffold dev
• Browse http://localhost:8088/greet/hello
• Change greeting in GreetingController to "Shalom", build app (gbx)
• Wait for rollout and browse http://localhost:8088/greet/hello
• Clean-up: ctrl-C

Debug

• Run skaffold debug
• This adds the agentlib JVM flag and reduces replicaset to 1
• Put a breakpoint in GreetingController
• Browse http://localhost:8088/greet/hello?name=Yaniv

Telepresence

Connect

• Deploy greeting & reverse with helm
• Check rollout status
• Present the reverse-service by browsing http://localhost:8088/greet/hello?name=World&reversed=true
• Run kubectl get svc reverse-service and show that this is a ClusterIP service, inaccessible from outside
• curl http://reverse-service.default/reverse/hello fails
• Run telepresence connect
• Run telepresence status
• Telepresence allows us to access the services as if we're in the cluster: curl http://reverse-service.default/reverse/hello now succeeds. We need to add the .<namespace> to the service name when we're not inside a pod that belongs to a specific namespace.
• Note: we can add any pod into our namespace and get the kube dns:
  • kubectl run curl -it --image=radial/busyboxplus:curl
  • In the shell, run: curl http://reverse-service/reverse/hello
  • How do we get the DNS suffix? Run cat /etc/resolv.conf
  • Clean-up: ctrl-c and then run kubectl delete pod curl

Intercept

• Run telepresence intercept reverse --port 8090 --env-file=./reverse.env
• Run reverse app locally on port 8090 (configure the app with the Intellij EnvFile plugin to pick up ./reverse.env)
• Now we don't need to qualify the service name with the namespace: curl http://reverse-service/reverse/hello
• Browse http://localhost:8088/greet/hello?name=Yaniv&reversed=true
• Edit ReverseController: add .append("***") and re-run. Refresh browser and see changes.
• Debug reverse: put a breakpoint in ReverseController and refresh the browser. You'll hit the breakpoint.

Cleanup

• telepresence leave reverse
• Refresh the browser (no "***")
• To remove all Telepresence component (kubectl get all -n ambassador): Run telepresence uninstall --everything
• telepresence quit