kubernetes.md

kubernetes

This file will contain some kubernetes commands. Most of them will be kept in oc.md. Instead of writing kubectleverywhere I use a alias k=kubectlso in the docs you will see k in a bunch of places. Instead of writing kubernetes i normally write k8s.

Debug

Debug pod

There are a few things i miss from OCP in kubernetes and this is among them. In OCP you can write oc debug node/ip-10-0-141-105.ec2.internal. And it will start a debug pod on your node that can mount the root dir for you. This enables you to debug nodes without having to ssh in to them.

I k8s you can solve it this way.

Notice the nodeSelector at the bottom of the yaml.

debug.yaml

apiVersion: v1
kind: Pod
metadata:
  name: debug
  namespace: default
spec:
  containers:
    - command:
        - /bin/sh
      resources:
        requests:
          memory: "16Mi"
          cpu: "10m"
        limits:
          memory: "64Mi"
          cpu: "100m"
      image: alpine:latest
      name: container-00
      securityContext:
        privileged: true
        runAsUser: 0
      tty: true
      volumeMounts:
        - mountPath: /host
          name: host
  volumes:
    - hostPath:
        path: /
        type: Directory
      name: host
  hostNetwork: true
  nodeSelector:
    kubernetes.io/hostname: your-host-name

And lets jump in to the host

k apply -f debug.yaml
k exec -it debug -n default -- /bin/sh
# To become root on the node from the pod:
chroot /host

Delete all pods in failed phases

kubectl get pod --all-namespaces --field-selector=status.phase==Failed
kubectl delete pod --all-namespaces --field-selector=status.phase==Failed

Delete pods in terminating

In general don't use this, but it might be needed if your kubelet have hanged and then restarted or something like that. There is no phase update when a pod is terminating what I can find. So some awk magic is needed.

kubectl get pods --all-namespaces | awk '{if ($4=="Terminating") print "kubectl delete pod " $2 " -n " $1 " --force";}' | sh