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#!/usr/bin/env bash
#
# kubens(1) is a utility to switch between Kubernetes namespaces.
# Copyright 2017 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
[[ -n $DEBUG ]] && set -x
set -eou pipefail
IFS=$'\n\t'
SELF_CMD="$0"
KUBENS_DIR="${XDG_CACHE_HOME:-$HOME/.kube}/kubens"
usage() {
cat <<"EOF"
USAGE:
kubens : list the namespaces in the current context
kubens <NAME> : change the active namespace of current context
kubens - : switch to the previous namespace in this context
kubens -h,--help : show this message
EOF
}
exit_err() {
echo >&2 "${1}"
exit 1
}
current_namespace() {
local cur_ctx
cur_ctx="$(current_context)" || exit_err "error getting current context"
ns="$($KUBECTL config view -o=jsonpath="{.contexts[?(@.name==\"${cur_ctx}\")].context.namespace}")" \
|| exit_err "error getting current namespace"
if [[ -z "${ns}" ]]; then
echo "default"
else
echo "${ns}"
fi
}
current_context() {
$KUBECTL config current-context
}
get_namespaces() {
$KUBECTL get namespaces -o=jsonpath='{range .items[*].metadata.name}{@}{"\n"}{end}'
}
escape_context_name() {
echo "${1//\//-}"
}
namespace_file() {
local ctx="$(escape_context_name "${1}")"
echo "${KUBENS_DIR}/${ctx}"
}
read_namespace() {
local f
f="$(namespace_file "${1}")"
[[ -f "${f}" ]] && cat "${f}"
return 0
}
save_namespace() {
mkdir -p "${KUBENS_DIR}"
local f saved
f="$(namespace_file "${1}")"
saved="$(read_namespace "${1}")"
if [[ "${saved}" != "${2}" ]]; then
printf %s "${2}" > "${f}"
fi
}
switch_namespace() {
local ctx="${1}"
$KUBECTL config set-context "${ctx}" --namespace="${2}"
echo "Active namespace is \"${2}\".">&2
}
choose_namespace_interactive() {
# directly calling kubens via fzf might fail with a cryptic error like
# "$FZF_DEFAULT_COMMAND failed", so try to see if we can list namespaces
# locally first
if [[ -z "$(list_namespaces)" ]]; then
echo >&2 "error: could not list namespaces (is the cluster accessible?)"
exit 1
fi
local choice
choice="$(_KUBECTX_FORCE_COLOR=1 \
FZF_DEFAULT_COMMAND="${SELF_CMD}" \
fzf --ansi || true)"
if [[ -z "${choice}" ]]; then
echo 2>&1 "error: you did not choose any of the options"
exit 1
else
set_namespace "${choice}"
fi
}
set_namespace() {
local ctx prev
ctx="$(current_context)" || exit_err "error getting current context"
prev="$(current_namespace)" || exit_error "error getting current namespace"
if grep -q ^"${1}"\$ <(get_namespaces); then
switch_namespace "${ctx}" "${1}"
if [[ "${prev}" != "${1}" ]]; then
save_namespace "${ctx}" "${prev}"
fi
else
echo "error: no namespace exists with name \"${1}\".">&2
exit 1
fi
}
list_namespaces() {
local yellow darkbg normal
yellow=$(tput setaf 3 || true)
darkbg=$(tput setab 0 || true)
normal=$(tput sgr0 || true)
local cur_ctx_fg cur_ctx_bg
cur_ctx_fg=${KUBECTX_CURRENT_FGCOLOR:-$yellow}
cur_ctx_bg=${KUBECTX_CURRENT_BGCOLOR:-$darkbg}
local cur ns_list
cur="$(current_namespace)" || exit_err "error getting current namespace"
ns_list=$(get_namespaces) || exit_err "error getting namespace list"
for c in $ns_list; do
if [[ -n "${_KUBECTX_FORCE_COLOR:-}" || \
-t 1 && -z "${NO_COLOR:-}" ]]; then
# colored output mode
if [[ "${c}" = "${cur}" ]]; then
echo "${cur_ctx_bg}${cur_ctx_fg}${c}${normal}"
else
echo "${c}"
fi
else
echo "${c}"
fi
done
}
swap_namespace() {
local ctx ns
ctx="$(current_context)" || exit_err "error getting current context"
ns="$(read_namespace "${ctx}")"
if [[ -z "${ns}" ]]; then
echo "error: No previous namespace found for current context." >&2
exit 1
fi
set_namespace "${ns}"
}
main() {
if [[ -z "${KUBECTL:-}" ]]; then
if hash kubectl 2>/dev/null; then
KUBECTL=kubectl
elif hash kubectl.exe 2>/dev/null; then
KUBECTL=kubectl.exe
else
echo >&2 "kubectl is not installed"
exit 1
fi
fi
if [[ "$#" -eq 0 ]]; then
if [[ -t 1 && -z ${KUBECTX_IGNORE_FZF:-} && "$(type fzf &>/dev/null; echo $?)" -eq 0 ]]; then
choose_namespace_interactive
else
list_namespaces
fi
elif [[ "$#" -eq 1 ]]; then
if [[ "${1}" == '-h' || "${1}" == '--help' ]]; then
usage
elif [[ "${1}" == "-" ]]; then
swap_namespace
elif [[ "${1}" =~ ^-(.*) ]]; then
echo "error: unrecognized flag \"${1}\"" >&2
usage
exit 1
elif [[ "${1}" =~ (.+)=(.+) ]]; then
alias_context "${BASH_REMATCH[2]}" "${BASH_REMATCH[1]}"
else
set_namespace "${1}"
fi
else
echo "error: too many flags" >&2
usage
exit 1
fi
}
main "$@"