kubernetes-notes.md

Kubernetes notes

This file contains notes on the Kubernetes cluster and its management.

Minikube and offline deployment

You can run an offline version of the app in minikube. The only extra step is to configure the database URI secret. You can set up an RDS instance and provide its URI as the secret, or you can have an in-memory database in the container running the database proxy. If you choose the latter, note that you must keep the replica count of the database proxy pods (populare-db-proxy) set to 1.

# From kubernetes-standalone/
kubectl create secret generic db-certs --from-literal=db-uri=sqlite:////tmp/populare_rds.db
kubectl apply -f populare-kubernetes.yaml

Create the application

kubectl apply -f populare-kubernetes.yaml

Check connection to DB proxy service

kubectl exec populare-<suffix> -- curl -s populare-db-proxy/health

Check connection to service within cluster

Note: you can't connect to a service from a container backing that service. This may be a minikube issue, but appears to be well-known. Instead, connect through the mock client.

kubectl exec mock-client-<suffix> -- curl -s populare

Open populare web app in browser using minikube

minikube service reverse-proxy

This is a shortcut that opens a browser window to the minikube node's IP address and the reverse-proxy service's nodeport. You could also get minikube's IP address with minikube ip and the nodeport with kubectl get svc reverse-proxy, then navigate to that IP/port in your browser.

Check node/pod CPU and memory usage

Checking CPU and memory usage requires a metrics server to be deployed.

kubectl top node
kubectl top pod