kubetool

#!/bin/sh

[[ -n $DEBUG ]] && set -x
set -eou pipefail

usage() {
  cat <<"EOF"
USAGE:
  kubetool                    : show this message
  kubetool ctx get            : gets the current context
  kubetool ctx set NAME       : sets the current context
  kubetool ctx ls,list        : lists all of the contexts
  kubetool ctx rename OLD NEW : renames a context from the old value to the new valud
  kubetool ns get             : get the current namespace for the current context
  kubetool ns set NAME        : set the current namespace for the current context
  kubetool ns ls,list         : list all namespaces for the current context
  kubetool -h,--help          : show this message
EOF
  exit 1
}

list_contexts() {
  kubectl config get-contexts -o=name | sort -n
}

get_context() {
  kubectl config view -o=jsonpath='{.current-context}'
}

set_context() {
  kubectl config use-context "${1}"
}

rename_context() {
  local ctx
  if [[ "${1}" == "." ]]; then
    ctx="$(get_context)"
  else
    ctx="${1}"
  fi
  kubectl config rename-context "${ctx}" "${2}"
}

list_namespaces() {
  kubectl get namespaces -o=jsonpath='{range .items[*].metadata.name}{@}{"\n"}{end}'
}

get_namespace() {
  local ctx
  ctx="$(get_context)"
  ns="$(kubectl config view -o=jsonpath="{.contexts[?(@.name==\"${ctx}\")].context.namespace}")"
  if [[ -z "${ns}" ]]; then
    echo "default"
  else
    echo "${ns}"
  fi
}

set_namespace() {
  local ctx
  ctx="$(get_context)"
  kubectl config set-context "${ctx}" --namespace="${1}"
}

main() {
  if [[ "$#" -eq 0 ]]; then
    usage
  elif [[ "${1}" == '-h' || "${1}" == '--help' ]]; then
    usage
  elif [[ "${1}" == "ns" ]]; then
    if [[ "$#" -eq 2 && "${2}" == "get" ]]; then
      get_namespace
    elif [[ "$#" -eq 2 && "${2}" == "ls" ]]; then
      list_namespaces
    elif [[ "$#" -eq 2 && "${2}" == "list" ]]; then
      list_namespaces
    elif [[ "$#" -eq 3 && "${2}" == "set" ]]; then
      set_namespace "${3}"
    else
      echo "error: invalid arguments" >&2
      usage
      exit 1
    fi
  elif [[ "${1}" == "ctx" ]]; then
    if [[ "$#" -eq 2 && "${2}" == "get" ]]; then
      get_context
    elif [[ "$#" -eq 2 && "${2}" == "ls" ]]; then
      list_contexts
    elif [[ "$#" -eq 2 && "${2}" == "list" ]]; then
      list_contexts
    elif [[ "$#" -eq 3 && "${2}" == "set" ]]; then
      set_context "${3}"
    elif [[ "$#" -eq  4 && "${2}" == "rename" ]]; then
      rename_context "${3}" "${4}"
    else
      echo "error: invalid arguments" >&2
      usage
      exit 1
    fi
  else
    echo "error: invalid arguments" >&2
    usage
    exit 1
  fi
}

main "$@"