Helpful Kubectl Commands

Over the years, I have learned a lot of kubectl commands and used a lot of tools to help me naviagate through the Kubernetes ecosystem. While tools like kubens and kubectx are great for switching between namespaces and contexts, I have found that most of the time, I just use bare kubectl commands. Here are some of the most common commands that I use on a daily basis and some extras that have helped me out in the past. For faster typing and less mistakes, I have aliased kubectl to k.

  

# add this to your shell profile to alias kubectl to k
alias k="kubectl"

  

General Navigation

Over the years, I have bounced around a lot between different namespaces and contexts and never really found a lot of use for setting kube config to point to a specific namespace. If you wanted to go that route, you just need to do something similar to kubectl config set-context <clusterName> --namespace=<nameSpace>. Here is a general list of commands I use to navigate around each cluster. While there are a lot of tools and GUI's for this, most of my time is spent in the terminal so all of these commands are for the terminal.

  

# showing the available clusters:
$ k config get-contexts
CURRENT   NAME             CLUSTER          AUTHINFO         NAMESPACE
          docker-desktop   docker-desktop   docker-desktop
          k3s              k3s-cluster      k3s-admin
          minikube         minikube         minikube         default
*         raspberry        raspberry        raspberry
          ubuntupi         ubuntupi         ubuntupi


# Selecting a cluster:
$ k config use-context k3s


# Display the context you are currently using:
$ k config current-context
k3s


# Show all available namespaces (ns is short for namespace):
$ k get ns
NAME              STATUS   AGE
...
argo-events       Active   148d
argo              Active   141d
default           Active   236d
sean-home         Active   136d
go-site-gin       Active   236d


# list resources in a namespace (note all doesn't mean everything)
$ k get all -n go-site-gin
NAME                               READY   STATUS    RESTARTS   AGE
pod/go-site-gin-76869976cd-klvhj   1/1     Running   0          4h40m

NAME                      TYPE       CLUSTER-IP   EXTERNAL-IP   PORT(S)          AGE
service/go-site-gin-svc   NodePort   10.43.3.39   <none>        8080:30090/TCP   236d

NAME                          READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/go-site-gin   1/1     1            1           128d

NAME                                     DESIRED   CURRENT   READY   AGE
replicaset.apps/go-site-gin-86df6c949f   0         0         0       128d
replicaset.apps/go-site-gin-799fdb896c   0         0         0       128d
replicaset.apps/go-site-gin-77b846d5bb   0         0         0       48d
...

  

Listing Kubernetes Api Resources

  

# show api version in k8s (really helpfull for building manifests):
$ k api-versions
admissionregistration.k8s.io/v1
apiextensions.k8s.io/v1
apiregistration.k8s.io/v1
apps/v1
argoproj.io/v1alpha1
authentication.k8s.io/v1
...


# Show the resources for the apis (great for finding shortcodes):
$ k api-resources -o wide
NAME                              SHORTNAMES           APIGROUP                       NAMESPACED   KIND                             VERBS
bindings                                                                              true         Binding                          [create]
componentstatuses                 cs                                                  false        ComponentStatus                  [get list]
configmaps                        cm                                                  true         ConfigMap                        [create delete deletecollection get list patch update watch]
endpoints                         ep                                                  true         Endpoints                        [create delete deletecollection get list patch update watch]
events                            ev                                                  true         Event                            [create delete deletecollection get list patch update watch]
...


# Explain a resource and its fields (drill in with dot notation):
$ k explain pod
KIND:     Pod
VERSION:  v1

DESCRIPTION:
     Pod is a collection of containers that can run on a host. This resource is
     created by clients and scheduled onto hosts.
...


# Dig further:
$ k explain pod.spec.serviceAccountName
KIND:     Pod
VERSION:  v1

FIELD:    serviceAccountName <string>

DESCRIPTION:
     ServiceAccountName is the name of the ServiceAccount to use to run this
     pod. More info:
     https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/

  

Modify Deployed Resources

These commands are great for testing and debugging, but when using tools like ArgoCD to manager your deployments, you will rarely use these commands. If you run these commands against a managed resource, you will likely find yourself fighting the reconciler and your changes will be reverted. In that cause you'll need to temporarily disable the reconciler or use the ArgoCD CLI to make changes.

  

# Scale a deployment:
$ k scale --replicas=2 deployment/<deployment-name> -n <namespace>


# edit a running resource (usually a deployment, configmap, or secret):
# it's also worth noting that you can use kubectl edit to edit a resource in your default editor
$ k edit deployment <deployment-name> -n <namespace>


# apply a localy stored manifest to the cluster:
$ k apply -f <path-to-manifest> -n <namespace>


# delete a resource:
$ k delete <resource> <resource-name> -n <namespace>


# if it was generated from a local file:
$ k delete -f <path-to-manifest> -n <namespace>


# removing pods with a grace period:
$ k delete pod <podName> --grace-period=10


# restarting a deployment
$ k rollout restart deployment <deployment-name> -n <namespace>


# get the status of a rollout
$ k rollout status deployment/<deployment-name> -n <namespace>

  

Moving Files Between Containers

  

# copy files from a container to your local machine:
$ k cp <pod-name>:<path-to-file> <path-to-destination> -n <namespace>


# copy files from your local machine to a container:
$ k cp <path-to-file> <pod-name>:<path-to-destination> -n <namespace>


# exec into a pod (if tty is enabled, you can use bash or sh to get a shell):
$ k exec -it <pod-name> -n <namespace> -- /bin/bash


# connect to a specific container in a pod:
$ k exec -it <pod-name> -c <container-name> -n <namespace> -- /bin/bash


# get values of a kubernetes secret using jsonpath:
$ k get secret <secret-name> -n <namespace> -o jsonpath='{.data.<key>}' | base64 --decode

  

Node Management

  

# get a list of nodes:
$ k get nodes
NAME      STATUS   ROLES                  AGE    VERSION
nd1-4gb   Ready    <none>                 235d   v1.27.3+k3s1
nd2-8gb   Ready    control-plane,master   236d   v1.27.3+k3s1


# describe a specific node:
$ k describe node <node-name>


# taint a node (for maintinance or to prevent workloads from being scheduled):
$ k taint <node-name> <taint-key>:<taint-value>:<taint-effect>
ex:
$ k taint nd1-4gb app:app:NoSchedule


# cordon off a node (prevent new workloads from being scheduled):
$ k cordon <node-name>


# drain a node (move workloads off of a node):
$ k drain <node-name>


# uncordon a node (allow workloads to be scheduled on a node):
$ k uncordon </node-name>


# remove a taint from a node (yes you will need that trailing dash):
$ k taint <node-name> <taint-key>:<taint-value>-

  

Misic Commands

  

# get a list of pods and their node assignments using custom-columns:
$ k get pod -o=custom-columns=NAME:.metadata.name,STATUS:.status.phase,NODE:.spec.nodeName,WORKLOAD:.spec.nodeSelector.workload -n chime01|grep compute


# get a list of nodes and the zone they are in (useful for draining a zone):
$ kk get nodes --no-headers -l failure-domain.beta.kubernetes.io/zone=us-east-1c | awk '{print $1}' | while read k8sNode


  

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