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README_K8S.md

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Kubernetes 🧊

This guide assumes the following:

  • docker or podman installed and running.
  • minikube installed.

Throughout this guide, for any command x, replace it with either docker or podman.

A note on Podman desktop setup

If using Podman and after installing all tooling from _macos/Brewfile:

  • Create VM in Podman desktop by completing the setup wizard.
  • Install Minikube extension in Podman desktop (see here) by installing ghcr.io/containers/podman-desktop-extension-minikube from OCI image.

Minikube + Docker/Podman setup

For full details, see

Using minikube and targeting either Docker or Podman:

  • Docker: minikube start --driver=docker
  • Podman: minikube start --driver=podman --container-runtime=cri-o

Adding additional registries (required for e.g. linkerd if using Podman):

  • Run minikube ssh to enter the Minikube VM.
  • Run sudo vi /etc/containers/registries.conf and add the following, which will help resolve short-name resolution issues (e.g. ImageInspectError problems).
unqualified-search-registries = ["docker.io", "quay.io"]

Verify Minikube setup

  • minikube status
  • kubectl config current-context
  • cat ~/.minikube/machines/minikube/config.json
  • cat ~/.kube/config

Minikube usage

Run cd templates/minikube for the below commands to work.

Build and push image

  • Build image with x build -t gohello:latest .
  • Tag image for deployment: x tag gohello:latest docker.io/fredrikaverpil/gohello:0.0.1.

Pushing images

There are several ways to push images to the Minikube cluster, see the official docs.

Build into the cluster

The easiest approach is to make docker build or podman build build images directly into the cluster. Run the following to set a series of environment variables which will tell Docker/Podman to build into the cluster:

  • eval $(minikube docker-env)
  • eval $(minikube podman-env)

Push image to Minikube cluster from Podman

  • Go into Podman Desktop -> Images.
  • Click the : button next to the image you want to push and choose "Push image to Minikube cluster".

This can be done on the commandline too, but is more involved. See details here.

Push to Dockerhub registry

  • Log into docker.io: x login docker.io.
  • Push image to dockerhub: x push docker.io/fredrikaverpil/gohello:0.0.1.

Note: to push a multi-architecture container, it's easier to use docker's buildx:

docker buildx create --name mybuilder --use
docker buildx build --platform linux/amd64,linux/arm64 -t docker.io/fredrikaverpil/gohello:0.0.1 --push .

Deploy to Minikube

Using helm:

  • Install chart with helm install gohello ./chart.

Using kubectl:

  • Create pod with kubectl apply -f ./\*.yaml.
  • Verify pod with kubectl get pods -n gohello

Using terraform:

  • Review deployment plan with terraform plan.
  • Create pod with terraform apply.
  • Verify pod with kubectl get pods -n gohello

Port-forward

Using helm:

  • Not needed, as the chart already has a service configured. Access in browser by executing minikube service gohello-svc -n gohello.

Using k9s:

  • Run by providing namespace k9s -n gohello or by switching namespace in k9s by hiting : followed by namespaces.
  • Find the gohello-container, hit shift-f and make it forward to localhost on port 8080.
  • Access in browser: http://localhost:8080/
  • Remove the port-forward by hitting f. This will show all active port-forwards. Hit ctrl+d to remove the entry from the list.

Using kubectl:

  • Port-forward to pod with kubectl port-forward pod/gohello-pod -n gohello 8080:9090.
  • Access in browser: http://localhost:8080/

Logs

Using k9s:

  • Run by providing namespace k9s -n gohello or by switching namespace in k9s by hiting : followed by namespaces.
  • Find the gohello-container, hit shift-l to view logs.

Using kubectl:

  • View logs with kubectl logs -n gohello gohello-pod.

Using stern:

  • View logs with stern -n gohello gohello-pod.

Debugging

Using helm:

  • Debug the helm chart with helm template ./chart --debug.
  • Lint the helm chart with helm lint ./chart

Using k9s:

  • Run by providing namespace k9s -n gohello or by switching namespace in k9s by hiting : followed by namespaces.
  • Find the gohello-container, hit shift-d to debug.

Using kubectl:

  • Debug with kubectl debug -n gohello gohello-pod.

Teardown

Using helm:

  • Delete chart with helm uninstall gohello.

Using kubectl:

  • Delete pod with kubectl delete -f ./\*.yaml.

Using terraform:

  • Tear down everything: terraform destroy.

Problem solving

  • Reset minikube cluster: minikube stop && minikube delete && minikube start --driver=podman --container-runtime=cri-o
  • Get minikube IP: minikube ip
  • Get minikube dashboard: minikube dashboard (enable metrics for more features: minikube addons enable metrics-server)
  • Something is already running on port XXXX; lsof -i :XXXX and kill -9 <PID>.
  • Remove cache of downloaded images from minikube:
    • minikube cache delete <image-name>
    • minikube cache delete --all
  • Validate helm chart with helm template ./chart --debug.