Kubernetes/Kubectl/Cheat Sheet
< Kubernetes | Kubectl
Introduction
More or less loose collection of kubectl commands that might be helpful (or were helpful at some point)
Commands
The all-namespaces commands need to be run from the admin service which is only accessible to root
kube_env admin codfw
List all images (without registry) running in the cluster
kubectl get pods --all-namespaces --field-selector=status.phase=Running -o jsonpath="{..image}" | tr ' ' '\n' | sed 's/.*\///' | sort -u
List images used per namespace
kubectl get pods --all-namespaces --field-selector=status.phase=Running -o=jsonpath='{range .items[*]}{"\n"}{.metadata.namespace}{":\t"}{range .spec.containers[*]}{.image}{", "}{end}{end}'
Check which image version a cronjob is using
kubectl get pod <pod in question> -o jsonpath='{range .spec.containers[*]}{.name}: {.image}{"\n"}{end}'
Run a cronjob manually
Notes: requires the job to have been applied previously. Please keep in mind that the job will probably run as well when its scheduled time comes, so consider changing its schedule to something like @yearly if you don't want it to run while the manual run is in progress.
kube_env admin <cluster>
kubectl create job -n <namespace> --from=cronjob/<cronjob name> <cronjob name>-manual
Peek into a helm deployment config
kubectl get cm staging.v1 -o jsonpath='{.data.release}' | base64 -d | gunzip | vim -
Peek into a k8s secret TLS certificate
kubectl get secret <SECRET> -o jsonpath='{.data.tls\.crt}' | base64 -d | openssl crl2pkcs7 -nocrl -certfile /dev/stdin | openssl pkcs7 -print_certs -text -noout
List all RBAC "Groups" referenced in the cluster
kubectl get clusterrolebindings.rbac.authorization.k8s.io,rolebindings.rbac.authorization.k8s.io -A -o go-template='{{range $i := .items}}{{range $i.subjects}}{{if eq .kind "Group"}}{{$i.metadata.namespace}}/{{$i.metadata.name}} emerges group: {{.name}}{{"\n"}}{{end}}{{end}}{{end}}'
Get all pods and their priorities
kubectl get po -A -o jsonpath='{range .items[*]}{@.metadata.namespace}/{@.metadata.name} {@.spec.priority}{"\n"}{end}'
Last termination reason and time
kubectl get po -l app=flink-session-cluster-taskmanager -o go-template='{{range .items}}{{$pod := .}}{{range .status.containerStatuses}}{{ if eq .name "flink-session-cluster-main-taskmanager"}}{{$pod.metadata.name}} {{.lastState.terminated.reason}} at {{.lastState.terminated.finishedAt}}{{"\n"}}{{end}}{{end}}{{end}}'
Get elected master component leaders
kubectl -n kube-system get leases.coordination.k8s.io
List all container images available per nodes
Be aware that this lists a maximum of 50 images per node, there might be more!
kubectl get nodes -o jsonpath='{range .items[*]}{.metadata.name}{"\n"}{range .status.images[*]}{"\t"}{.names[0]}{"\n"}{end}{end}'
Force refresh of a cert-manager certificate
kubectl patch certificate/<CERTIFICATE> --type=json --patch='[{"op": "replace", "path": "/spec/renewBefore", "value": "1440h"}]'
# Once it's renewed, delete renewBefore
kubectl patch certificate/<CERTIFICATE> --type=json --patch='[{"op": "remove", "path": "/spec/renewBefore"}]'