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Useful commands

  • I'll post some interesting commands I used in the past think that they are helpful at least for me :-)

port forwarding

  • access via jumphost
# on jumphost
k port-forward -n <NAMESPACE> services/<SERVICE> <LOCAL_PORT_JUMPHOST>:<SERVICE_PORT>

# on local machine
ssh -L <LOCAL_PORT>:localhost:<LOCAL_PORT_JUMPHOST> jumphost

multi-attach error

  • when you try to scale down nodes it might happen that some pods can't be moved because of Multi-Attach error for volume
  • you can see these error by describing the pods and see events like below:
k describe pods -n <NAMESPACE> <POD>

# Events: Multi-Attach error for volume "pvc-uuid" Volume is already exclusively attached to one node and can't be attached to another.
  • to solve this in a smei-automated way you can use the following lines:
NODE=<OLD_NODE>
k get pods -A -owide | grep $NODE
k get volumeattachments.storage.k8s.io -o custom-columns=":metadata.name,:spec.nodeName" | grep $NODE | cut -d" " -f1 | xargs -r -t -L1 kubectl patch volumeattachments.storage.k8s.io --patch '{"metadata":{"finalizers":null}}' --type merge
k get volumeattachments.storage.k8s.io -o custom-columns=":metadata.name,:spec.nodeName" | grep $NODE | cut -d" " -f1 | xargs -r -t -L1 kubectl delete volumeattachments.storage.k8s.io
k delete node $NODE

Node NotReady taint

  • nodes that are in NotReady state can be tainted by the following command to remove them in a correct way:

kubectl taint node <NODENAME> node.kubernetes.io/out-of-service:NoExecute