- Introduction
- Namespace
- Pods
- Replicasets
- Deployment
- Service
- ConfigMaps
- Secrets
- Imperative commands
- SSH into container
- Service Account
- Nodes
- Label
- Selectors
- Taints and Tolerations
- Logs
- Monitoring
- Rolling update and rollback
- Dry run
- Alias
- Jobs
- CronJobs
- Ingress
- Network Policies
https://kubernetes.io/docs/reference/kubectl/quick-reference/
| Command | Purpose |
|---|---|
| kubectl get | Get summarized view of resources. Use -o for custom formats like json, yaml |
| kubectl describe | Get detailed information about a specific resource. Event & status section helpful for debugging |
| kubectl create | Creates a new resource. Fails if the resource already exists. |
| kubectl apply | Creates or updates a resource. |
| kubectl run | Creates & run single container pod on Kubernetes |
| kubectl expose | Creates service to expose pod or deployment or replicaset on Kubernetes |
| kubectl replace | Update an existing resource in a Kubernetes cluster |
kubectl get namespace
kubectl get ns
kubectl create namespace dev-ns
kubectl get pods
kubectl get pods -o wide
kubectl get po
kubectl delete pod <pod-name>
kubectl describe pod <pod-name>
kubectl get pods --all-namespaces
kubectl run redis --image=redis
kubectl get replicasets
kubectl get rs
kubectl get replicaset <replicaset-name> -o yaml
kubectl describe replicaset <replicaset-name>
kubectl create -f replicaset-definition.yaml
kubectl apply -f replicaset-definition.yaml
kubectl edit replicaset <replicaset-name>
kubectl scale replicaset <replicaset-name> --replicas=5
kubectl scale rs <replicaset-name> --replicas=5
kubectl get deployment
kubectl get deploy
kubectl create deployment <deployment-name> --image=<image-name> --replicas=3
kubectl scale deploy <deployment-name> --replicas=2
kubectl get service
kubectl get svc
kubectl get configmaps
kubectl get cm
kubectl create configmap webapp-config-map --from-literal=APP_COLOR=darkblue --from-literal=APP_OTHER=disregard
kubectl get secrets
kubectl create secret generic webapp-config-map --from-literal=password=nidhish --from-literal=host=example.com
# NOTE: Secrets are NOT encrypted, but encoded.
# NOTE: Run below command in Linux to encode/decode
echo -n 'nidhish' | base64
echo -n 'bmlkaGlzaA==' | base64 --decode
# create a pod with redis image
kubectl run redis --image=redis
# Create a pod with name as redis, image as redis:alpine and label labelname=labelvalue
kubectl run redis -l labelkey=labelvalue --image=redis:alpine
# Create a service redis-service to expose the redis application within the cluster on port 6379
kubectl expose pod redis --port=6379 --name redis-service
# Create a deployment named webapp using the image kodekloud/webapp-color with 3 replicas
kubectl create deployment webapp --image=kodekloud/webapp-color --replicas=3
# Create a new namespace called dev-ns
kubectl create namespace dev-ns
# Create a pod called httpd using the image httpd:alpine in the default namespace. Next, create a service of type ClusterIP by the same name (httpd). The target port for the service should be 80
kubectl run httpd --image=httpd:alpine --port=80 --expose
SSH into app container
# Get list of pods
kubectl get po
# SSH into a pod
kubectl exec -it <pod-name> -- /bin/sh
# check environment variable of the pod (Optional)
env
# Get user of running pod
kubectl exec ubuntu-sleeper -- whoami
kubectl get serviceaccounts
kubectl get sa
kubectl create serviceaccount dashboard-sa
kubectl create token dashboard-sa
kubectl get nodes
kubectl get no
kubectl get no -o wide
kubectl label nodes node01 color=blue
kubectl get all --selector env=prod
kubectl get po --selector env=prod --selector=bu=finance --selector tier=frontend
# Add taint to a node (Example: node01)
kubectl taint nodes node01 spray=mortein:NoSchedule
# Remove taint from node (Example: control-plane)
kubectl taint nodes control-plane node-role.kubernetes.io/control-plane:NoSchedule-
kubectl get logs <pod-name>
# Get live streaming of logs
kubectl get logs <pod-name> -f
kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml
kubectl top pods
kubectl top nodes
Deployment Strategy
- Recreate - Delete and recreate deployments, causing downtime..
- Rolling Update - This is the default deployment strategy. It upgrades one instance at a time—bringing it down, completing the upgrade, and then proceeding to the next. This ensures zero downtime.
# Check the rollout status of a deployment
kubectl rollout status deployment/<deployment-name>
# Check the rollout history of a deployment
kubectl rollout history deployment/<deployment-name>
# Rollback the deployment
kubectl rollout undo deployment/<deployment-name>
kubectl run nginx --image=nginx --dry-run=client -o yaml
# Set temporary alias on Windows Command Prompt
doskey k=kubectl
kubectl get jobs
# Create job using imerative commands
kubectl create job <job-name> --image=<image-url>
kubectl delete job <job-name>
A Job that can be scheduled
kubectl get cronjob
# Create cron job using imerative commands
kubectl create cronjob <job-name> --image=<image-url> --schedule="*/5 * * * *" -- /bin/sh -c 'echo "Hello, Kubernetes!"'
kubectl delete cronjob <job-name>
kubectl get ingress --all-namespaces
kubectl create ingress simple --rule="foo.com/bar=svc1:8080"
kubectl get networkpolicies
kubectl get netpol