Kubernetes Zero Downtime demo

This project is for demonstrating the different elements for setting up zero downtime deployments.

Summary

This demostrates three different levels of zero downtime deployments

1. Barebones nginx deployment
2. Added readiness and liveness probes
3. Added preStop lifecycle hook with sleep statement

Requirements

• A local kubernetes cluster, I'll provide instructions for minikube but kind would also work
• kubectl
• kustomize (should be included with kubectl)
• An http load tester, I recommend siege

Steps

• Start the minikube cluster with minikube start
• Install the traefic ingress controller by running the traefik-install-helm script
• Connect to the traefik load balancer from localhost by running minikube tunnel in a new terminal window
• Apply the base nginx deployment in the k8s folder with kubectl apply -k k8s
• Start running siege siege -v 127.0.0.1 -c 2
• Modify the nginx deployment manifest
• Redeploy with kubectl apply -k k8s and monitor the HTTP responses, you should see multiple 502 responses as the pods are terminated and started
• Add the readiness / liveness probes to the deployment by running kubectl apply -k kustom-probes
• Modify the nginx deployment manifest again and redeploy, you should see less 502 responses
• Add the prestop lifecycle hook to the deploy by running kubectl apply -k kustom-prestop-hook
• Modify the nginx deployment manifest one more time and redeploy, you should see all 200 responses!