AhmetB started an excellent thread yesterday where he asked people to share a Kubernetes CLI (kubectl) tip that they think a lot of users don't know about.

There are so many excellent tips I decided to collect the most interesting ones in a single post. The first thing that I typically do when I am on a new machine is to set the alias for kubectl:

If you're working with Kubernetes, you'll be typing kubectl a lot, so why not make it shorter.

Enjoy the tips below and let us know if you have any other tips you want to share. Here are all the tips in no particular order.

1. Set up load-based horizontal pod autoscaling on your Kubernetes resources

kubectl autoscale deployment foo --min=2 --max=10

2. Create a new job from a cronjob

kubectl create job --from=cronjob/<name of cronjob> <name of this run>

3. Enumerate permissions for a given service account

kubectl -n <namespace> auth can-i --list --as system:serviceaccount:<namespace>:<service account name>

4. Annotate resources

# To add annotation
kubectl annotate <resource-type>/<resource-name> foo=bar
# To remove annotation
kubectl annotate <resource-type>/<resource-name> foo-

5. Get a list of endpoints across all namespaces

6. Get a list of events sorted by lastTimestamp

kubectl get events --sort-by=".lastTimestamp"

7. Watch all warnings across the namespaces

kubectl get events -w --field-selector=type=Warning -A

8. Add the EVENT column to the list of watched pods

kubectl get pods --watch --output-watch-events

9. Get raw JSON for the various APIs

kubectl get --raw /apis/apps/v1

# Get metrics
kubectl get --raw /metrics

10. Wait for specific pods to be ready

kubectl wait --for=condition=ready pod -l foo=bar

11. Explain the various resources

12. Get all resources that match a selector

kubectl get deployments,replicasets,pods,services --selector=hello=yourecute

13. Forward a port from a service to a local port

kubectl port-forward svc/<service-name> <local-port>:<remote-port>

14. List the environment variables for a resource

kubectl set env <resource>/<resource-name> --list

15. Get a list of pods and the node they run on

kubectl get po -o=custom-columns=NODE:.spec.nodeName,NAME:.metadata.name

16. Create a starter YAML manifest for deployment (also works for other resources)

kubectl create deploy nginx-deployment --image=nginx --dry-run=client -o yaml

17. Get a list of pods sorted by memory usage

kubectl top pods -A --sort-by='memory'

18. Get a list of pods that have a specific label value set

kubectl get pods -l 'app in (foo,bar)'

19. Get the pod logs before the last restart

kubectl logs <pod-name> --previous

20. Copy a file from a pod to a local file

kubectl cp <namespace>/<pod>:<file_path> <local_file_path>

kubectl delete pod <pod-name> --now

22. Show the logs from pods with specific labels

23. Get more information about the resources (aka wide-view)

kubectl get <resource> -o wide

24. Output and apply the patch

# Edit a resource and get the patch
kubectl edit <resource>/<name> --output-patch

# Use the output from the command above to apply the patch
kubectl patch --patch=<output_from_previous_command>