kubectl reference guide

4 min read | by Jordi Prats

Generic kubectl usage:

kubectl config view: Create an empty kubeconfig for Pods
kubectl logs previous: Using kubectl logs previous we can get the logs of the already restarted container
kubectl patch: Using kubectl patch we can modify Kubernetes objects in batch mode
kubectl explain: man for Kubernetes: With kubectl we have a sort of man to get the details of default Kubernetes objects
kubectl rollout history: By adding the record flag we can automatically set the change-cause annotation
kubectl set image: With kubectl set image we can update a container's image imperativelly
kubectl port-forward: Using kubectl port-forward we can reach services that are not exposed using other methods
kubectl run to create a pod: Let's see how to run a pod on kubernetes and it's equivalent docker commands
kubectl: create a yaml base template: By combining dry-run and yaml output we can use kubectl to create yaml templates for creating new resources on the cluster
retrieve yaml manifest for a given kubernetes object: Using kubectl we can retrieve the yaml manifest of any kubernetes object
kubectl diff usage: kubectl diff can be used to see the actual changes that will be performed by applying a given yaml file
kubectl top: kubectl top can be use to get a gist of what's going on on our cluster, resource-wise

krew

kubectl plugins: krew blame: Using kubectl blame we can identify when (and how) a field has been updated
Check cluster for deprecated objects: Using the krew deprecations we can identify which objects need to be updated before updating the cluster
kubectl get-all plugin: Using the krew plugin get-all we can list all the objects on a Kubernetes cluster
kubectl tree: Using kubectl tree we can visualize relationships between kubernetes objects
kubectl plugins: krew - unused-volumes plugin: kubectl plugin: unused-volumes to list PVC that are not assigned to any pod in the cluster

status of the API server: Using kubectl get --raw we can get the status of Kubernete's API server
Manually evict a Pod from a node: Using kubectl drain we can evict a Pod from a node
Kubernetes remove taint: Using kubectl taint we can also remove taints
kubernetes: uncordon node: Using kubectl uncordon remove the SchedulingDisabled from a node
kubernetes: drain node: Safely put a kubernetes node into maintenance mode

Autoscale a deployment base on it's Pod CPU metrics: A Kubernetes application can be autoscaled base on it's CPU usage using an HPA
kubectl rollout undo for rolling back releases: Kubernetes: Using kubectl rollout undo we can rollback to a previous state
Update on a deployment triggers a rolling update: When we update a deployment object Kubernetes will trigger by default a rolling update
Scaling deployments using kubectl scale: To be able to scale kubernetes deployments we don't need to edit it's yaml, we can use kubectl scale

How to get events from multiple kubernetes objects: kubectl get events can help us to better understand how the events happen across multiple objects

Using labels for filtering pods with kubectl: The selector option for kubectl commands helps filtering pods based on it's labels
sort kubernetes objects using kubectl: kubectl can sort objects by specifying any numeric or string field using it's JSON path

Set the default namespace for kubectl: If you need to work on a specific namespace you can set the it as your default namespace instead of repeating yourself on each kubectl command
Change kubectl context to use another k8s cluster: By switching kubectl context we can start working on a different cluster