k8s.md

tags
k8s kubernetes kubectl

Get number of attached volumes per node

kubectl get nodes -ogo-template='{{range .items}}{{ if .status.volumesAttached }}{{.metadata.name}} - {{.status.volumesAttached | len}}{{"\n"}}{{end}}{{end}}'

Note: This only works in non-CSI environments.

Decode secrets

kubectl get secret my-secret -ogo-template='{{index .data "config.yaml" | base64decode}}'

Run kubectl as serviceaccount

kubectl -n kube-public --as system:serviceaccount:monitoring:prometheus-operator get prometheusrules

Run a debug DaemonSet

see gist runs in kube-system debug-ds.yaml

kubectl apply -f https://gist.githubusercontent.com/chrigl/6184d4de911052711b149665829ce66d/raw/11ec5a0196fd0c8f415e7a3faf53e68e523d66e4/debug-ds.yaml

Get logs of previous terminated container

kubectl logs -p -c ruby web-1

Find all jobs in BackLimitExceeded

No error handling here, so be prepared for jq: error (at <stdin>:17450): Cannot iterate over null (null)

kubectl  get jobs -ojson -A | jq -r '.items[] | select(.status.conditions[] | select(.reason=="BackoffLimitExceeded" and .type == "Failed" and .status == "True")) | [.metadata.namespace, .metadata.name] | @tsv'

ingress nginx

Hmm. Maybe not the right place here, but good for now.

ingress-nginx doesn't write the the full configuration to /etc/nginx/nginx.conf but uses lua for some parts. There is a tool /dbg in the container to help debugging.

$ /dbg --help
dbg is a tool for quickly inspecting the state of the nginx instance

Usage:
  dbg [command]

Available Commands:
  backends    Inspect the dynamically-loaded backends information
  certs       Inspect dynamic SSL certificates
  completion  Generate the autocompletion script for the specified shell
  conf        Dump the contents of /etc/nginx/nginx.conf
  general     Output the general dynamic lua state
  help        Help about any command

Flags:
  -h, --help              help for dbg
      --status-port int   Port to use for the lua HTTP endpoint configuration. (default 10246)

Use "dbg [command] --help" for more information about a command.

Split resource list into a multi document yaml

kubectl -n cortex get ingress -oyaml | yq e '.items[] | split_doc'