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Kubectl

Kubectl Definition

Kubectl is a command line tool for controlling Kubernetes clusters.

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.

Resource types and it's aliases⚑

Resource Name Short Name
clusters
componentstatuses cs
configmaps cm
daemonsets ds
deployments deploy
endpoints ep
event ev
horizontalpodautoscalers hpa
ingresses ing
jobs
limitranges limits
namespaces ns
networkpolicies netpol
nodes no
statefulsets sts
persistentvolumeclaims pvc
persistentvolumes pv
pods po
podsecuritypolicies psp
podtemplates
replicasets rs
replicationcontrollers rc
resourcequotas quota
cronjob
secrets
serviceaccount sa
services svc
storageclasses
thirdpartyresources

Usage⚑

Port forward / Tunnel to an internal service⚑

If you have a service running in kubernetes and you want to directly access it instead of going through the usual path, you can use kubectl port-forward.

kubectl port-forward allows using resource name, such as a pod name, service replica set or deployment, to select the matching resource to port forward to. For example, the next commands are equivalent:

kubectl port-forward mongo-75f59d57f4-4nd6q 28015:27017
kubectl port-forward deployment/mongo 28015:27017
kubectl port-forward replicaset/mongo-75f59d57f4 28015:27017
kubectl port-forward service/mongo 28015:27017

The output is similar to this:

Forwarding from 127.0.0.1:28015 -> 27017
Forwarding from [::1]:28015 -> 27017

If you don't need a specific local port, you can let kubectl choose and allocate the local port and thus relieve you from having to manage local port conflicts, with the slightly simpler syntax:

$: kubectl port-forward deployment/mongo :27017

Forwarding from 127.0.0.1:63753 -> 27017
Forwarding from [::1]:63753 -> 27017

Run a command against a specific context⚑

If you have multiple contexts and you want to be able to run commands against a context that you have access to but is not your active context you can use the --context global option for all kubectl commands:

kubectl get pods --context <context_B>

To get a list of available contexts use kubectl config get-contexts

Namespaces⚑

Temporary set the namespace for a request⚑

kubectl -n {{ namespace_name }} {{ command_to_execute }}
kubectl --namespace={{ namespace_name }} {{ command_to_execute }}

Permanently set the namespace for a request⚑

kubectl config set-context --current --namespace={{ namespace_name }}

To make things easier you can set an alias:

alias kn='kubectl config set-context --current --namespace '

To unset the namespace use kubectl config set-context --current --namespace=""