Skip to content

Latest commit

 

History

History
251 lines (220 loc) · 8.12 KB

kubectl-command-sample.md

File metadata and controls

251 lines (220 loc) · 8.12 KB
Raw

Kubectl Sample Commands

The Kubernetes command-line tool, kubectl, allows you to run commands against Kubernetes clusters. You can use kubectl to deploy applications, inspect and manage cluster resources, and view logs. For more information including a complete list of kubectl operations, see the kubectl reference documentation.

Overview of kubectl

The kubectl command line tool lets you control Kubernetes clusters. For configuration, kubectl looks for a file named config in the $HOME/.kube directory. You can specify other kubeconfig files by setting the KUBECONFIG environment variable or by setting the --kubeconfig flag.

This overview covers kubectl syntax, describes the command operations, and provides common examples. For details about each command, including all the supported flags and subcommands, see the kubectl reference documentation. For installation instructions see installing kubectl.

Syntax

Use the following syntax to run kubectl commands from your terminal window:

kubectl [command] [TYPE] [NAME] [flags]

  • command: Specifies the operation that you want to perform on one or more resources, for example create, get, describe, delete.

  • TYPE: Specifies the resource type. Resource types are case-insensitive and you can specify the singular, plural, or abbreviated forms. For example, the following commands produce the same output:

  • NAME: Specifies the name of the resource. Names are case-sensitive. If the name is omitted, details for all resources are displayed, for example kubectl get pods.

  • flags: Specifies optional flags. For example, you can use the -s or --server flags to specify the address and port of the Kubernetes API server.

kubectl bash completion

kubectl completion bash  > /etc/bash_completion.d/kubectl

kubectl config

kubectl config current-context
kubectl config view
kubectl config set-context dev --namespace=development \
  --cluster=lithe-cocoa-92103_kubernetes \
  --user=lithe-cocoa-92103_kubernetes
kubectl config use-context dev
kubectl config view --kubeconfig my-kube-config
kubectl config --kubeconfig=/root/my-kube-config use-context research

expose api on 8001 port

kubectl proxy

get all object

kubectl get all --all-namespaces

node commands

kubectl get node
kubectl edit node msater
kubectl get nodes --show-labels
kubectl drain <node name>
kubectl uncordon <node name>
kubectl drain node01 --ignore-daemonsets
kubectl describe node master
kubectl cordon node03

taints

kubectl taint nodes <node-name> key=value:taint-effect
kubectl taint nodes node1 app=blue:NoSchedule

logs

kubectl logs -f event-simulator-pod
kubectl logs -f <pod-name> <container-name>
kubectl logs -f even-simulator-pod event-simulator

pod

kubectl get pods -n kube-system
kubectl get pods -o wide
kubectl get pods -l app=snowflake -n=development
kubectl run nginx --image=nginx --namespace=<insert-namespace-name-here>
kubectl get pods --namespace=<insert-namespace-name-here>
kubectl get pods --selector env=dev
kubectl get all --selector env=prod,bu=finance,tier=frontend
kubectl logs my-custom-scheduler -n kube-system

service

kubectl get services
kubectl describe service

namespace

kubectl create ns test
kubectl create namespace dev
kubectl get pods --namespace=test
kubectl run redis --image=redis --namespace=test
kubectl get pods --all-namespaces
kubectl create -f pod-definition.yaml --namespace=dev
kubectl get namespaces

run pod without manifest

kubectl run httpd --image=httpd:alpine --port=80 --expose
kubectl run nginx-pod --image=nginx:alpine
kubectl run redis --image=redis:alpine -l tier=db
kubectl run custom-nginx --image=nginx --port=8080
kubectl run httpd --image=httpd:alpine --port=80 --expose
kubectl get pods --selector app=App1

expose

kubectl expose pod redis --port=6379 --name redis-service

secret

kubectl get secrets
kubectl describe secret
kubectl create secret generic db-secret --from-literal=DB_Host=sql01 --from-literal=DB_User=root --from-literal=DB_Password=password123

deployment

kubectl create deployment webapp --image=kodekloud/webapp-color
kubectl get deployment
kubectl get replicaset
kubectl get rs
kubectl describe deployment
kubectl create deployment httpd-frontend --image=httpd:2.4-alpine 
kubectl scale deplyoment httpd-frontend --replicas=3
kubectl edit deployment.v1.apps/nginx-deployment
kubectl rollout status deployment/nginx-deployment
kubectl rollout undo deployment.v1.apps/nginx-deployment
kubectl scale deployment.v1.apps/nginx-deployment --replicas=10
kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:sometag
kubectl scale deployment blue --replicas=6
kubectl scale deployment.v1.apps/nginx-deployment --replicas=10
kubectl autoscale deployment.v1.apps/nginx-deployment --min=10 --max=15 --cpu-percent=80

rollout

kubectl rollout status deployment/myapp-deployment
kubectl rollout history deployment/myapp-deployment
kubectl rollout undo deployment/myapp-deployment

Network Policies

kubectl get networkpolicy
kubectl describe networkpolicy

daemonsets

kubectl get daemonsets --all-namespaces
kubectl describe daemonset kube-proxy --namespace=kube-system
kubectl describe daemonset kube-flannel-ds-amd64 --namespace=kube-system

label

kubectl label node ubuntu owner=alpin         # add label
kubectl label node ubuntu owner-              # remove label

scale

kubectl scale deployment/webapp --replicas=3
# You can also use kubectl scale deployment or kubectl edit deployment to change the number of replicas once the object has been created.
kubectl edit deployment redis-deploy
kubectl scale deployment/redis-deploy --replicas=2 --namespace=dev-ns

ConfigMaps

kubectl create configmap app-config --from-literal=APP_COLOR=blue --from-literal=APP_MODE=prod
kubectl create configmap app-config --from-file=app_config.properties (Another way)

set

kubectl set image deployment/myapp-deployment nginx=nginx:1.9.1

Cluster Roles

kubectl get clusterroles --no-headers | wc -l (or)
kubectl get clusterroles --no-headers -o json | jq '.items | length'
kubectl get clusterrolebindings --no-headers | wc -l (or)
kubectl get clusterrolebindings --no-headers -o json | jq '.items | length'
kubectl describe clusterrolebinding cluster-admin

check access

kubectl auth can-i create deployments
kubectl auth can-i delete nodes
kubectl auth can-i create deployments --as dev-user
kubectl auth can-i create pods --as dev-user
kubectl auth can-i create pods --as dev-user --namespace test

RBAC

kubectl get roles
kubectl get rolebindings
kubectl describe role developer
kubectl describe rolebinding devuser-developer-binding

create sample yaml file

kubectl run --restart=Never --image=busybox static-busybox --dry-run=client -o yaml --command -- sleep 1000 > /etc/kubernetes/manifests/static-busybox.yaml

create yaml file with scenario

# Step 1: Create the deployment YAML file
kubectl create deployment redis-deploy --image redis --namespace=dev-ns --dry-run=client -o yaml > deploy.yaml
kubectl create -f deploy.yaml

# Step 2: Edit the YAML file and add update the replicas to 2.

#Step 3: Run kubectl apply -f deploy.yaml to create the deployment in the dev-ns namespace.
kubectl apply -f deploy.yaml


# check certificate commands
```bash
openssl x509 -in /etc/kubernetes/pki/ca.crt -text
openssl x509 -in /etc/kubernetes/pki/apiserver.crt -text
openssl x509 -in /etc/kubernetes/pki/etcd/server.crt -text

Create new labels

You can create own labels

kubectl label nodes <node-name> <label-key>=<label-value>

Example

kubectl label nodes minikube foo=bar

json pacth

kubectl get nodes -o jsonpath='{.items[*].status.addresses[?(@.type=="InternalIP")].address}' > /root/CKA/node_ips
kubectl get nodes -o=jsonpath='{.items[*].metadata.name}'
kubectl get nodes -o jsonpath='{.items[*].status.nodeInfo.osImage}'

Good Cammands:

kubectl drain <NODE_NAME> --ignore-daemonsets --delete-local-data