k8s snippets

finalizer example

Use this when k8s is stuck deleting a resource
kubectl patch <resource type>/<resource name> -p '{"metadata":{"finalizers":[]}}' --type=merge
Example,
kubectl patch pus/pu -p '{"metadata":{"finalizers":[]}}' --type=merge

helm

# this works similar to force delete
helm delete <chart name> --no-hooks

# show all charts, even ones that were not successfully deleted
helm list -aA
    -a no filter applied (uninstalling releases not shown otherwise)
    -A all namespaces

k8s troubleshooting, debug

1. Show previous failed deployment logs (useful if the pod starts but then crashes and restarts).
kubectl logs --previous <pod name> -n <namespace>

2. Describe pod will show events
kubectl describe pod <pod name>

Alternatively, get pod events (useful if the k8s cluster contains many pods and only interested in a single pod)
kubectl get event --namespace <namespace> --field-selector involvedObject.name=<pod name>

Or get events but sort by timestamp
kubectl get events --sort-by='.metadata.creationTimestamp'

3. Debug initContainers. Show initContainer statuses.
Example:
kubectl get pod <pod name> --template '{{.status.initContainerStatuses}}'

4. Get logs for an initcontainer
kubectl logs <pod name> -c <init container name>

Kubernetes documentation
Debug main page: https://kubernetes.io/docs/tasks/debug/debug-application/
Debug initContainer subtopic: https://kubernetes.io/docs/tasks/debug-application-cluster/debug-init-containers/
Debug pod subtopic: https://kubernetes.io/docs/tasks/debug/debug-application/debug-running-pod/

minikube cheatsheet

# restore context of minikube, when using tools such kubectl
minikube update-context

pretty print kubectl node info

 kubectl get nodes -o wide |  awk {'print $1" " $2 " " $7'} | column -t

show all images used

kubectl get pod -o="custom-columns=NAME:.metadata.name,INIT-CONTAINERS:.spec.initContainers[*].name,INIT-CONTAINERS-IMAGE:.spec.initContainers[*].image,CONTAINERS:.spec.containers[*].name,CONTAINERS-IMAGE:.spec.containers[*].image"
NAME                            INIT-CONTAINERS                                 INIT-CONTAINERS-IMAGE                      CONTAINERS                     CONTAINERS-IMAGE
grafana-6fc5bf87d7-87nl7        <none>                                          <none>                                     grafana-sc-dashboard,grafana   quay.io/kiwigrid/k8s-sidecar:1.19.2,grafana/grafana:9.2.5
influxdb-0                      <none>                                          <none>                                     influxdb                       influxdb:1.8.10
xap-dgw-xap-pu-0                <none>                                          <none>                                     pu-container                   gigaspaces/smart-cache-enterprise:16.4.2
xap-manager-0                   check-external-service-ready                    gigaspaces/smart-cache-enterprise:16.4.2   gigaspaces-container           gigaspaces/smart-cache-enterprise:16.4.2
xap-operator-68fd794b6f-tnvxv   create-keystore,wait-for-master-before-starup   alpine/openssl,busybox:1.36.0              xap-operator                   gigaspaces/cache-operator:16.4.2

troubleshooting helm charts

# get values passed into helm release
helm get values demo -n dih
                ^ release name

# Option 1
# generate manifests that would be used for helm install
# can redirect output to a file and treated like a regular k8s manifest, using kubectl apply -f 
helm template dih ./dih -f new-release-values.yaml -n dih --debug
              ^ release name
                  ^ local chart
                        ^ yaml file containing list of override values
                                                          ^ debug is optional (from what I've seen does not add much value).
# Option 2 - more verbose, but option 1 usually provides what is needed
# generate manifests but has a section that shows computed values
helm install dih dih/dih -n dih --dry-run --debug