CodeWizards Kubernetes demo

This is a very top level introduction to the most basic Kubernetes resources. You should be able to deploy a workload to a cluster with the information given here. There is so much more to kubernetes than what is contained here, but have fun getting your feet wet :)

Requirements

• A POSIX compliant shell, OSX and Linux have this out the box (iTerm, etc), and Windows users can use Git Bash
• minikube (local kubernetes cluster)
• kubectl (command line interface)
• helm (kubernetes template/package manager)

Setup

Initialise minikube:

minikube config set profile minikube
minikube config set memory 8192
minikube config set cpus 4
minikube start --extra-config=kubelet.housekeeping-interval=10s
minikube addons enable ingress
minikube addons enable metrics-server
minikube addons enable dashboard

Basic commands

kubectl api-resources shows you all the resource types the cluster knows about - there are many in here, and more can be added but for the purpose of this example you only need worry about:

• pods
• services (svc)
• deployments (deploy)
• ingresses (ing)
• configmaps (cm)
• secrets
• horizontalpodautoscalers (hpa)

kubectl get RESOURCE_TYPE is the "listing" operator on various resources.

kubectl describe RESOURCE_TYPE RESOURCE_NAME gets detailed information on the desired resource

kubectl apply -f MANIFEST_FILE will create the resources in the given file

kubectl delete -f MANIFEST_FILE will delete the resources in the given file

Examples

kubectl get pods will list the pods in the current namespace

kubectl describe pod blue-app will give you info on the blue-app pod

Getting to grips with Kubernetes

There is an official web dashboard to get a view on what is going on, however it is not recommended for production. If you aren't very comfortable with the cli then it's a good jumping off point.

To view the dashboard

minikube dashboard --url

This will give you an in-terminal link you can click to go to the Web UI

Now we want an IP to talk to the cluster with

minikube ip

Alter your hosts file with a few new hosts

OSX/Linux: /etc/hosts In windows: Alter the hosts file at c:\windows\system32\drivers\etc\hosts

YOUR.MINIKUBE.IP.ADDRESS 	green.local
YOUR.MINIKUBE.IP.ADDRESS 	blue.local
YOUR.MINIKUBE.IP.ADDRESS 	example1.local

You can now apply each manifest file with the following syntax (except the files in the helm directory!)

kubectl apply -f PATH_TO_FILE

You can delete resources in the same way

kubectl delete -f PATH_TO_FILE

Try applying these files, and alter them if you want to see what happens

• configmap/configmap.yaml
• deployments/deployments.yaml
• secrets/secrets.yaml
• ingress/ingress.yaml
• pods/pod-volumes.yaml

Try deploying them in a random order and see what happens, what if you create a pod that references a volume that doesn't exist?

You can use the kubectl describe RESOURCE command to try debug what went wrong.

Have a look at the results at http://green.local and http://blue.local!

You can install a copy of the included helm template with:

helm install NAME_OF_APP ./helm-example

Make sure you add a host entry

YOUR.MINIKUBE.IP.ADDRESS 	NAME_OF_APP.local

Run a load test!

kubectl run -i --tty \
	load-generator \
	--rm --image=busybox:1.28 \
	--restart=Never -- /bin/sh -c \
	"while sleep 0.01; do wget -q -O- http://NAME_OF_APP-service; done"

Note that the wget command is using address of the service, as the service is our service-discovery based routing endpoint.

Watch it scale with the CLI or by watching the pod tab in the dashboard

kubectl get hpa NAME_OF_APP-scaler --watch

Example wordpress install

Setup another minikube cluster:

minikube delete -p wordpress
minikube start -p wordpress
minikube config set profile wordpress
minikube update-context wordpress
minikube addons enable ingress

Note: as this is a new cluster, the previous dashboard will not show you the resources you are about to deploy. To access the new web dashboard, run the minikube dashboard --url command again.

Install wordpress:

First tell helm that you want to include charts from the bitnami repository

helm repo add bitnami https://charts.bitnami.com/bitnami

Now tell helm to install it! Note some of the parameters here, have a go changing the hostname if you want to put it on a different host!

helm install my-site bitnami/wordpress \
	--set service.type=ClusterIP \
	--set ingress.enabled=true \
	--set ingress.ingressClassName=nginx \
	--set ingress.hostname=wordpress.local \
	--set ingress.pathType=Prefix \
	--set ingress.path=/ \
	--set persistence.storageClass=standard \
	--set wordpressPassword=password \
	--set mariadb.auth.rootPassword=password \
	--set mariadb.auth.password=password \
	--version 13.1.16

The above will take some time to get ready, you can check the status of the installation with:

kubectl get pods

Once thats up, add it to your hosts

In Linux/OSX:

echo "$(minikube ip)	wordpress.local" | sudo tee -a /etc/hosts > /dev/null

In windows: Alter the hosts file at c:\windows\system32\drivers\etc\hosts

Further reading

• Service meshes eg linkerd/Istio - very handy for canary releases
• Nginx Ingress - youll probably have to deal with nginx at some point!
• Prometheus - metric aggregation
• DataDog - log collection
• Grafana - incredible dashboarding tool
• OAuth2 Proxy - versatile auth barrier that plugs into most federated identity providers allowing you to secure dashboards to authenticated authorised users (eg the grafana ui!)
• Tailscale - wireguard based vpn to secure cluster access
• Operators - how to extend Kubernetes
• Pager Duty - alerting tool to tell you when things have gone wrong
• ArgoCD - have your cluster look at a git repository to make its updates