kubectl evict in bash

kubectl-evict

#!/bin/bash

print_usage () {
  printf 'Usage: kubectl evict -n <namespace> <pod>\n' >&2
}

main () {
  if [ "-n" != "$1" ] && [ "--namespace" != "$1" ]
  then
    print_usage
    return 1
  fi
  shift
  # TODO handle arbitrary argument order

  local ns=$1 pod=$2
  if [ -z "${ns}" ] && [ -z "${pod}" ]
  then
    print_usage
    return 1
  fi

  local body sock_dir kubectl_proxy_pid curl_exit counter
  printf -v body '{"apiVersion":"policy/v1beta1","kind":"Eviction","metadata":{"namespace":"%s","name":"%s"}}' \
    "${ns}" "${pod}"

  sock_dir=$(mktemp -d)
  kubectl proxy -u "${sock_dir}/kube.sock" >/dev/null &
  kubectl_proxy_pid=$!
  sleep 1

  counter=15
  while [ ! -e "${sock_dir}/kube.sock" ] && [ 0 -lt "${counter}" ]
  do
    sleep 0.1
    counter=$((counter - 1))
  done

  if ! kill -n 0 "${kubectl_proxy_pid}"
  then
    wait "${kubectl_proxy_pid}"
    return
  fi

  curl --unix-socket "${sock_dir}/kube.sock" \
    -d "${body}" \
    -H 'Content-Type: application/json' \
    -s -o /dev/null -w '%{http_code}\n' \
    "http://localhost/api/v1/namespaces/${ns}/pods/${pod}/eviction"
  #TODO curl --retry to honour 429's retry-header response (assuming v7.66+)
  curl_exit=$?

  kill "${kubectl_proxy_pid}"
  wait "${kubectl_proxy_pid}" 2>/dev/null

  rm -f "${sock_dir}/kube.sock"
  rm -d "${sock_dir}"

  return "${curl_exit}"
}

main "$@"