Kubernetes - Refresher Notes

This post is for anyone to quickly refresh on the phrases in Kubernetes. If you are starting to explore Kubernetes then this can be used as a checklist on the areas you should be aware of. I have also included some basic commands to work with kubernetes.

Concepts :

• KUBECONFIG
• Cluster - Master & Worker
• Node
• Node Port
• ClusterIP
• Statefulset vs Statetless
• Deployment
• Service
• Pod
• Namespace
• Context
• PersistentVolume
• PersistentVolumeClaim
• HostPath (Local)
• Ingress
• LoadBalancer
• ConfigMap
• Secrets
• DNS (..svc.cluster.local)
• KubeAdmin
• RBAC
• ServiceAccount
• Rollout
• Replica Scale

Scripts

• Annotations,Labels & Selectors
• Kustomize (-k vs -f)
• Apply/Create/Patch

Local Kubernetes Setup :

• Docker for Desktop Mac
• MiniKube

Tools

• Kubernetes Dashboard - web UI for Kubernetes clusters
• Kubectl and Proxy
• Kubernetic Desktop - View Cluster Resources, Similar to Kitematic for Docker.
• Sekret - Encryption Tool for Kubernetes Secrets YAML
• Kamus - Encryption and Decryption solution for Kubernetes applications
• Kubectx - Switch faster between clusters and namespaces in kubectl
• kube-ps1 - Kubernetes prompt info for bash and zsh to see the current cluster context with namespace
• Kubefwd - Bulk port forwarding Kubernetes services for local development.

Basic Commands

Contexts

# Get all contexts
kubectl config get-contexts 

# Get Current Context
kubectl config current-context


# Set the default context
kubectl config use-context nk-dev-cluster  

kubectl config set-context nk-dev --namespace=rafa-dev --cluster=docker-for-desktop-cluster --user=docker-for-desktop

Describe K8 Resources

# kubectl describe <resource> <resourceName>
kubectl describe pods pod1

# Get the resource definition in yaml
kubectl get pod my-pod -o yaml 

Expose a Service

#expose a app named web-app as a service 

kubectl expose deployment web-app --name=web-app --type=NodePort --target-port=8080


# For Testing Locally
kubectl port-forward servicename 8080:8080

Connect to the running Pod Container

kubectl exec web-app-fcc6b5ddf-k2txq -it -- /bin/sh

Troubleshooting

#Simple Container to quickly run some curl commands to the pods
kubectl run curl-test --image=radial/busyboxplus:curl -i --tty --rm

Thanks for reading this refresher.