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K8s_Cheat_Sheet.md

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Cheat sheet to run useful commands on K8s deployed cluster

Tested on Centos 7.6 + K8s 1.15

  1. Below are some of the useful commands
kubectl explain deployment
kubectl explain deployment --recursive
kubectl explain deployment.spec.strategy

kubectl cluster-info dump
kubectl get componentstatus
kubectl get namespace
kubectl get pods --all-namespaces
kubectl get pods --namespace=ns-demo -o wide
kubectl get pods -n ns-demo -o wide
kubectl config view
kubectl get node k8snode01 -o yaml
kubectl get pods $PODNAME -o yaml
kubectl get pods $PODNAME -o json
kubectl get pods -l environment=lab
kubectl get pods -l 'environment in (lab, qa)'
kubectl get nodes --show-labels
kubectl describe node "nodename"
kubectl describe pod label-nginx-demo
kubectl label nodes <node-name> <label-key>=<label-value>
kubectl create -f node2-pod1.yaml
kubectl delete -f node2-pod1.yaml
kubectl replace -f node2-pod1.yaml
kubectl get pods --field-selector status.phase=Running
kubectl cordon $NODENAME
kubectl logs $PODNAME
kubectl create -f replicaset-pod.yaml --dry-run
kubectl apply -f deployment-pod.yaml
kubectl get rs
kubectl get deployments
kubectl rollout status deployment.v1.apps/nginx-deployment
kubectl edit deployment.v1.apps/nginx-deployment
kubectl exec -it nginx-deployment-7448597cd5-6k8kb bash
kubectl describe deployment $DEPLOYMENT
kubectl rollout history deployment.v1.apps/nginx-deployment
kubectl rollout undo deployment.v1.apps/nginx-deployment
kubectl get deployment nginx-deployment
kubectl scale deployment.v1.apps/nginx-deployment --replicas=10
kubectl autoscale deployment.v1.apps/nginx-deployment --min=10 --max=15 --cpu-percent=80
kubectl get deploy
kubectl rollout pause deployment.v1.apps/nginx-deployment
kubectl set resources deployment.v1.apps/nginx-deployment -c=nginx --limits=cpu=200m,memory=512Mi
kubectl rollout resume deployment.v1.apps/nginx-deployment
kubectl get rs -w
kubectl rollout status deployment.v1.apps/nginx-deployment
kubectl patch deployment.v1.apps/nginx-deployment -p '{"spec":{"progressDeadlineSeconds":600}}'
kubectl describe jobs/job-pi
pods=$(kubectl get pods --selector=job-name=job-pi --output=jsonpath='{.items[*].metadata.name}');echo $pods
kubectl get pods $PODNAME -o yaml --export
kubectl exec -it $PODNAME -- cat /etc/resolv.conf
kubectl get pods -l run=svc-nginx -o wide
kubectl get pods -l run=svc-nginx -o yaml | grep podIP
kubectl get svc
kubectl get svc $SVCNAME
kubectl describe svc $SVCNAME
kubectl get endpoints
kubectl get endpoints $SVCNAME
kubectl scale deployment $SVCNAME --replicas=0
kubectl scale deployment $SVCNAME --replicas=3
kubectl get services kube-dns --namespace=kube-system
kubectl get svc $SVCNAME -o yaml | grep nodePort -C 5
kubectl delete pod -n=kube-system coredns-fb8b8dccf-8ggcf
kubectl get pods -n kube-system -oname |grep coredns |xargs kubectl delete -n kube-system
kubectl get deployment coredns -n kube-system -o yaml > dns.yaml
kubectl get crds
kubectl exec -it $PODNAME -- /bin/bash
kubectl get virtualservices   
kubectl get destinationrules 
kubectl get gateway         
kubectl get namespace -L istio-injection
kubectl -n istio-system port-forward \
  $(kubectl -n istio-system get pod -l app=grafana -o jsonpath='{.items[0].metadata.name}') \
  3000:3000 &
kubectl get virtualservice
kubectl get secrets
kubectl create namespace <ns-name>
kubectl get pod,svc -o wide -n kube-system
kubectl get MeshPolicy default
kubectl get rule -n istio-system
kubectl run np-web --image=nginx --labels app=web --expose --port 80

kubectl get nodes --show-labels 
kubectl label node 192.168.0.185 node-role.kubernetes.io/master=true
kubectl label node 192.168.0.185 node-role.kubernetes.io/master-
kubectl  get pods --no-headers=true -n kube-system
kubectl get nodes --show-labels | tail -n +2 | awk '{print $1" "$5}'
journalctl -u kubelet
  1. Allow pods on master node
kubectl taint nodes --all node-role.kubernetes.io/master-
  1. Monitor events
docker run -v /var/run/docker.sock:/var/run/docker.sock -ti alpine sh
apk update && apk add curl

curl --unix-socket /var/run/docker.sock http://localhost/events
  1. Create Docker Registry Secret
cat <<EOF | kubectl apply -f -
---
apiVersion: v1
kind: Secret
metadata:
  name: regcred
data:
  .dockerconfigjson: $(echo "{\"auths\": {\"https://index.docker.io/v1/\": {\"auth\": 
            \"$(echo "JNPR-CustXXXXX:xxxxxxxxxxx" | base64)\"}}}" | base64)
type: kubernetes.io/dockerconfigjson
EOF
  1. Delete namespace in terminating state
kubectl get namespace "contrail" -o json | tr -d "\n" | sed "s/\"finalizers\": \[[^]]\+\]/\"finalizers\": []/" | \
        kubectl replace --raw /api/v1/namespaces/contrail/finalize -f -

kubectl get namespace "contrail-analytics" -o json | tr -d "\n" | sed "s/\"finalizers\": \[[^]]\+\]/\"finalizers\": []/" | \
        kubectl replace --raw /api/v1/namespaces/contrail-analytics/finalize -f -

kubectl get namespace "contrail-deploy" -o json | tr -d "\n" | sed "s/\"finalizers\": \[[^]]\+\]/\"finalizers\": []/" | \
        kubectl replace --raw /api/v1/namespaces/contrail-deploy/finalize -f -

kubectl get namespace "contrail-system" -o json | tr -d "\n" | sed "s/\"finalizers\": \[[^]]\+\]/\"finalizers\": []/" | \
        kubectl replace --raw /api/v1/namespaces/contrail-system/finalize -f -
  1. Delete all resources running in a namespace
kubectl delete all --all -n <namespace>
kubectl delete namespace <namespace>
  1. Patch
kubectl patch svc portal -n contrail-analytics --type='json' -p '[{"op":"replace","path":"/spec/type","value":"NodePort"}]'
  1. Pods not running
kubectl get pods --field-selector status.phase!=Running --all-namespaces

Reference

Kubernetes