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commands.md

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Get help on commands

kubectl <command> -h

Get explanation for resource fields

kubectl explain RESOURCE [options]
e.g.: kubectl explain deployment.spec.template

Define helpers

export now="--force --grace-period 0"

export do="--dry-run=client -o yaml"

Delete pods without waiting

kubectl delete pod NAME $now

Create resource definitions and pipe to file

ConfigMap

kubectl create configmap NAME [--from-file=[key=]source]
[--from-literal=key1=value1] [--dry-run=server|client|none] [options]

e.g.: kubectl create configmap sample-cm $do > sample-cm.yaml

Deployment

kubectl create deployment NAME --image=IMAGE -- [COMMAND] [args...] [options]

e.g.: kubectl create deployment NAME --image=image $do > my-deployment.yaml

Ingress

kubectl create ingress NAME --rule=host/path=service:port[,tls[=secret]]  [options]

e.g. kubectl create ingress example-ingress --rule=hello-world.info/=web:8080 $do > hello-world-ingress.yaml

Pod

kubectl run NAME --image=image [--env="key=value"] [--port=port] [--dry-run=server|client] [--overrides=inline-json] [--command] -- [COMMAND] [args...] [options]

e.g.: kubectl run nginx --image=nginx $do > my-pod.yaml

Role

kubectl create role NAME --verb=verb --resource=resource.group/subresource [--resource-name=resourcename] [--dry-run=server|client|none] [options]

e.g. kubectl create role testadmin --verb='*' --resource='*' $do > my-role.yaml

RoleBinding

kubectl create rolebinding NAME --clusterrole=NAME|--role=NAME [--user=username] [--group=groupname] [--serviceaccount=namespace:serviceaccountname] [--dry-run=server|client|none] [options]

e.g. ubectl create rolebinding testadminbinding --role=testadmin --serviceaccount=test1:myaccount $do > tastadmin-role-binding.yaml

Secret

kubectl create secret [flags] [options]

e.g. kubectl create secret generic NAME --from-literal=password=very_complex $do > literal.yaml

Service

kubectl create service [flags] [options]

e.g. kubectl create service TYPE NAME --tcp=80 $do > my-svc.yaml

or e.g. kubectl expose deployment NAME --type=NodePort --port=9000

Get a Shell to a Running Container

Documentation

kubectl exec --it POD_NAME --container CONTAINER_NAME -- sh

or

kubectl exec -i -t POD_NAME --container CONTAINER_NAME -- sh -c "clear; (bash || ash || sh)"

Interactive Throw-Away Pod for e.g. Debugging

kubectl run -it --image nicolaka/netshoot dns-test --restart=Never --rm

kubectl Cheat Sheet

https://kubernetes.io/docs/reference/kubectl/cheatsheet/

Taints/Tolerations, nodeSelector, nodeName

Taint

kubectl taint nodes NODE_NAME KEY_1=VAL_1:TAINT_EFFECT_1 ... KEY_N=VAL_N:TAINT_EFFECT_N [options]

Tolerations

Pod specification:

tolerations:
- key: "key1"
  # operator: "Equal" # set only if `value` not specified
  value: "value1"
  effect: "NoSchedule"

effect: NoSchedule | PreferNoSchedule | NoExecute

nodeSelector

Select node by label in pod specification:

spec:
	containers:
	- ...
	nodeSelector:
		<LabelKey>: <LabelValue>

nodeName

Select node by name in pod specification:

spec:
	containers:
	- ...
	nodeName: <NodeName>

Scale Deployment

kubectl scale --replicas=<REPLICAS> deployment/<DEPLOYMENT_NAME>

Rollback Deployment

Check rollout status: kubectl rollout status deployment/<DEPLOYMENT_NAME>

Check rollout history: kubectl rollout history deployment/<DEPLOYMENT_NAME>

Check revision details: kubectl rollout history deployment/<DEPLOYMENT_NAME> --revison=

Rollback to previous revision: kubectl rollout undo deployment/<DEPLOYMENT_NAME>

Rollback to specific revision: kubectl rollout undo deployment/<DEPLOYMENT_NAME> --to-revision=<NUMBER>

crictl

https://kubernetes.io/docs/tasks/debug/debug-cluster/crictl/

Used to debug container runtimes on a node.