Kubernetes

A cheat sheet for Kubernetes commands.

Kubernetes Cheat Sheet

A cheat sheet for Kubernetes commands.

Kubectl Alias

Linux

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alias k=kubectl

Windows

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Set-Alias -Name k -Value kubectl

Cluster Info

• Get clusters

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kubectl config get-clusters
NAME
docker-for-desktop-cluster
foo

• Get cluster info.

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kubectl cluster-info
Kubernetes master is running at https://172.20.0.58:8443

Contexts

A context is a cluster, namespace and user.

• Get a list of contexts.

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kubectl config get-contexts

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CURRENT   NAME                 CLUSTER                      AUTHINFO             NAMESPACE
          docker-desktop       docker-desktop               docker-desktop
*         foo                  foo                          foo                  bar

• Get the current context.

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kubectl config current-context
foo

• Switch current context.

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kubectl config use-context docker-desktop

• Set default namesapce

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kubectl config set-context $(kubectl config current-context) --namespace=my-namespace

Get Commands

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kubectl get all
kubectl get namespaces
kubectl get configmaps
kubectl get nodes
kubectl get pods
kubectl get rs
kubectl get svc 
kubectl get endpoints <svcname>

Additional switches that can be added to the above commands:

• -o wide - Show more information.
• --watch or -w - watch for changes.

Namespaces

• --namespace - Get a resource for a specific namespace.

You can set the default namespace for the current context like so:

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kubectl config set-context $(kubectl config current-context) --namespace=my-namespace

Labels

• Get pods showing labels.

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kubectl get pods --show-labels

• Get pods by label.

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kubectl get pods -l environment=production,tier!=frontend
kubectl get pods -l 'environment in (production,test),tier notin (frontend,backend)'

Describe Command

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kubectl describe nodes [id]
kubectl describe pods [id]
kubectl describe rs [id]
kubectl describe svc  [id]
kubectl describe endpoints <svcname> [id]

Delete Command

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kubectl delete nodes [id]
kubectl delete pods [id]
kubectl delete rs [id]
kubectl delete svc  [id]
kubectl delete endpoints <svcname> [id]

Force a deletion of a pod without waiting for it to gracefully shut down

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kubectl delete pod-name --grace-period=0 --force

Create vs Apply

kubectl create can be used to create new resources while kubectl apply inserts or updates resources while maintaining any manual changes made like scaling pods.

• --record - Add the current command as an annotation to the resource.
• --recursive - Recursively look for yaml in the specified directory.

Create Pod

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kubectl run <name> --generator=run-pod/v1 --image=<imagename:tag> --output yaml --export --dry-run > <name>.yml
kubectl apply -f <name>.yml

Create Deployment

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kubectl run <name> --image=<imagename:tag> --output yaml --export --dry-run > deployment.yml
kubectl apply -f deployment.yml

Create Service

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kubectl expose deployment <servicename> --port 8080 --target-port=8080 --output yaml --export --dry-run > <servicename>.yml
kubectl apply -f <servicename>.yml

Export YAML for New Pod

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kubectl run my-cool-app -image=me/my-cool-app:v1 --output yaml --export --dry-run > my-cool-app.yaml

Export YAML for Existing Object

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kubectl get deployment my-cool-app --output yaml --export > my-cool-app.yaml

Logs

• Get logs.

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kubectl logs -l app=<appname>

• Get logs for previously terminated container.

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kubectl logs POD_NAME --previous

• Watch logs in real time.

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kubectl attach POD_NAME

• Copy files out of pod (Requires tar binary in container).

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kubectl cp POD_NAME:/var/log .

Port Forward

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kubectl port-forward deployment/<deploymentname> 8080:8080

Scaling

• Update replicas.

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kubectl scale deployment nginx-deployment --replicas=10

Autoscaling

• Set autoscaling config.

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kubectl autoscale deployment nginx-deployment --min=10 --max=15 --cpu-percent=80

Rollout

• Get rollout status.

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kubectl rollout status deployment/nginx-deployment
Waiting for rollout to finish: 2 out of 3 new replicas have been updated...
deployment "nginx-deployment" successfully rolled out

• Get rollout history.

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kubectl rollout history deployment/nginx-deployment
kubectl rollout history deployment/nginx-deployment --revision=2

• Undo a rollout.

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kubectl rollout undo deployment/nginx-deployment
kubectl rollout undo deployment/nginx-deployment --to-revision=2

• Pause/resume a rollout

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kubectl rollout pause deployment/nginx-deployment
kubectl rollout resume deploy/nginx-deployment

Pod Example

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apiVersion: v1
kind: Pod
metadata:
  name: cuda-test
spec:
  containers:
    - name: cuda-test
      image: "k8s.gcr.io/cuda-vector-add:v0.1"
      resources:
        limits:
          nvidia.com/gpu: 1
  nodeSelector:
    accelerator: nvidia-tesla-p100

Deployment Example

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apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: my-namespace
  labels:
    - environment: production,
    - teir: frontend
  annotations:
    - key1: value1,
    - key2: value2
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        ports:
        - containerPort: 80

Dashboard

• Enable proxy

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kubectl proxy

Azure Kubernetes Service

Get Credentials

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az aks get-credentials --resource-group <Resource Group Name> --name <AKS Name>

Show Dashboard

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az aks browse --resource-group <Resource Group Name> --name <AKS Name>

Upgrade

Get updates

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az aks get-upgrades --resource-group <Resource Group Name> --name <AKS Name>

For More please Visit Kubernetes Documentation

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