updating kube-ps1 to align with upstream changes (#6995)

plugins/kube-ps1/README.md

-Kubernetes prompt for zsh
-=========================
+# Kubernetes prompt for zsh
 
-A Kubernetes (k8s) zsh prompt that displays the current cluster cluster
+A Kubernetes zsh prompt that displays the current cluster cluster
 and the namespace.
 
 Inspired by several tools used to simplify usage of kubectl
 
-NOTE: If you are not using zsh, check out [kube-ps1](https://github.com/jonmosco/kube-ps1) designed for bash
-as well as zsh.
+NOTE: If you are not using zsh, check out [kube-ps1](https://github.com/jonmosco/kube-ps1)
+designed for bash as well as zsh.
 
 ## Requirements
 
@@ -32,28 +31,33 @@ fast switching between clusters and namespaces.
 The prompt layout is:
 
 ```
-(<logo>|<cluster>:<namespace>)
+(<symbol>|<cluster>:<namespace>)
 ```
 
-Supported platforms:
-* k8s - Kubernetes
-* ocp - OpenShift
+## Enabling
 
-## Install
+In order to use kube-ps1 with Oh My Zsh, you'll need to enable them in the
+.zshrc file. You'll find the zshrc file in your $HOME directory. Open it with
+your favorite text editor and you'll see a spot to list all the plugins you
+want to load.
 
-1. Clone this repository
-2. Source the kube-ps1.zsh in your ~./.zshrc
-
-ZSH:
+```shell
+vim $HOME/.zshrc
 ```
-source path/kube-ps1.sh
-PROMPT='$(kube_ps1) '
+
+Add kube-ps1 to the list of enabled plugins:
+
+```shell
+plugins=(
+  git
+  kube-ps1
+)
 ```
 
 ## Colors
 
-The colors are of my opinion. Blue was used as the prefix to match the Kubernetes
-color as closely as possible. Red was chosen as the cluster name to stand out, and cyan
+Blue was used as the prefix to match the Kubernetes color as closely as
+possible. Red was chosen as the cluster name to stand out, and cyan
 for the namespace.  These can of course be changed.
 
 ## Customization
@@ -62,14 +66,15 @@ The default settings can be overridden in ~/.zshrc
 
 | Variable | Default | Meaning |
 | :------- | :-----: | ------- |
-| `KUBE_PS1_DEFAULT` | `true` | Default settings for the prompt |
+| `KUBE_PS1_BINARY` | `kubectl` | Default Kubernetes binary |
 | `KUBE_PS1_PREFIX` | `(` | Prompt opening character  |
-| `KUBE_PS1_DEFAULT_LABEL` | `⎈ ` | Default prompt symbol |
+| `KUBE_PS1_SYMBOL_ENABLE` | `true ` | Display the prompt Symbol. If set to `false`, this will also disable `KUBE_PS1_SEPARATOR` |
+| `KUBE_PS1_SYMBOL_DEFAULT` | `⎈ ` | Default prompt symbol. Unicode `\u2388` |
+| `KUBE_PS1_SYMBOL_USE_IMG` | `false` | ☸️  ,  Unicode `\u2638` as the prompt symbol |
+| `KUBE_PS1_NS_ENABLE` | `true` | Display the namespace. If set to `false`, this will also disable `KUBE_PS1_DIVIDER` |
 | `KUBE_PS1_SEPERATOR` | `\|` | Separator between symbol and cluster name |
-| `KUBE_PS1_PLATFORM` | `kubectl` | Cluster type and binary to use |
 | `KUBE_PS1_DIVIDER` | `:` | Separator between cluster and namespace |
 | `KUBE_PS1_SUFFIX` | `)` | Prompt closing character |
-| `KUBE_PS1_DEFAULT_LABEL_IMG` | `false` | Use Kubernetes img as the label: ☸️  |
 
 ## Contributors
 

plugins/kube-ps1/kube-ps1.plugin.zsh

 #!/bin/zsh
 
 # Kubernetes prompt helper for bash/zsh
+# ported to oh-my-zsh
 # Displays current context and namespace
 
-# Copyright 2017 Jon Mosco
+# Copyright 2018 Jon Mosco
 #
 #  Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -21,32 +22,39 @@
 [[ -n $DEBUG ]] && set -x
 
 setopt PROMPT_SUBST
-add-zsh-hook precmd _kube_ps1_load
+autoload -U add-zsh-hook
+add-zsh-hook precmd _kube_ps1_update_cache
 zmodload zsh/stat
+zmodload zsh/datetime
 
 # Default values for the prompt
-# Override these values in ~/.zshrc or ~/.bashrc
-KUBE_PS1_DEFAULT="${KUBE_PS1_DEFAULT:=true}"
-KUBE_PS1_PREFIX="("
-KUBE_PS1_DEFAULT_LABEL="${KUBE_PS1_DEFAULT_LABEL:="⎈ "}"
-KUBE_PS1_DEFAULT_LABEL_IMG="${KUBE_PS1_DEFAULT_LABEL_IMG:=false}"
-KUBE_PS1_SEPERATOR="|"
-KUBE_PS1_PLATFORM="${KUBE_PS1_PLATFORM:="kubectl"}"
-KUBE_PS1_DIVIDER=":"
-KUBE_PS1_SUFFIX=")"
-KUBE_PS1_UNAME=$(uname)
+# Override these values in ~/.zshrc
+KUBE_PS1_BINARY="${KUBE_PS1_BINARY:-kubectl}"
+KUBE_PS1_SYMBOL_ENABLE="${KUBE_PS1_SYMBOL_ENABLE:-true}"
+KUBE_PS1_SYMBOL_DEFAULT="${KUBE_PS1_SYMBOL_DEFAULT:-\u2388 }"
+KUBE_PS1_SYMBOL_USE_IMG="${KUBE_PS1_SYMBOL_USE_IMG:-false}"
+KUBE_PS1_NS_ENABLE="${KUBE_PS1_NS_ENABLE:-true}"
+KUBE_PS1_SEPARATOR="${KUBE_PS1_SEPARATOR-|}"
+KUBE_PS1_DIVIDER="${KUBE_PS1_DIVIDER-:}"
+KUBE_PS1_PREFIX="${KUBE_PS1_PREFIX-(}"
+KUBE_PS1_SUFFIX="${KUBE_PS1_SUFFIX-)}"
 KUBE_PS1_LAST_TIME=0
 
-kube_ps1_label () {
+_kube_ps1_binary_check() {
+  command -v "$1" >/dev/null
+}
 
-  [[ "${KUBE_PS1_DEFAULT_LABEL_IMG}" == false ]] && return
+_kube_ps1_symbol() {
+  [[ "${KUBE_PS1_SYMBOL_ENABLE}" == false ]] && return
 
-  if [[ "${KUBE_PS1_DEFAULT_LABEL_IMG}" == true ]]; then
-    local KUBE_LABEL="☸️ "
-  fi
+  KUBE_PS1_SYMBOL="${KUBE_PS1_SYMBOL_DEFAULT}"
+  KUBE_PS1_SYMBOL_IMG="\u2638 "
 
-  KUBE_PS1_DEFAULT_LABEL="${KUBE_LABEL}"
+  if [[ "${KUBE_PS1_SYMBOL_USE_IMG}" == true ]]; then
+    KUBE_PS1_SYMBOL="${KUBE_PS1_SYMBOL_IMG}"
+  fi
 
+  echo "${KUBE_PS1_SYMBOL}"
 }
 
 _kube_ps1_split() {
@@ -56,23 +64,45 @@ _kube_ps1_split() {
 }
 
 _kube_ps1_file_newer_than() {
-
   local mtime
   local file=$1
   local check_time=$2
-  mtime=$(stat +mtime "${file}")
 
-  [ "${mtime}" -gt "${check_time}" ]
+  zmodload -e "zsh/stat"
+  if [[ "$?" -eq 0 ]]; then
+    mtime=$(stat +mtime "${file}")
+  elif stat -c "%s" /dev/null &> /dev/null; then
+    # GNU stat
+    mtime=$(stat -c %Y "${file}")
+  else
+    # BSD stat
+    mtime=$(stat -f %m "$file")
+  fi
 
+  [[ "${mtime}" -gt "${check_time}" ]]
 }
 
-_kube_ps1_load() {
-  # kubectl will read the environment variable $KUBECONFIG
-  # otherwise set it to ~/.kube/config
+_kube_ps1_update_cache() {
   KUBECONFIG="${KUBECONFIG:=$HOME/.kube/config}"
+  if ! _kube_ps1_binary_check "${KUBE_PS1_BINARY}"; then
+    # No ability to fetch context/namespace; display N/A.
+    KUBE_PS1_CONTEXT="BINARY-N/A"
+    KUBE_PS1_NAMESPACE="N/A"
+    return
+  fi
 
-  for conf in $(_kube_ps1_split : "${KUBECONFIG}"); do
-    # TODO: check existence of $conf
+  if [[ "${KUBECONFIG}" != "${KUBE_PS1_KUBECONFIG_CACHE}" ]]; then
+    # User changed KUBECONFIG; unconditionally refetch.
+    KUBE_PS1_KUBECONFIG_CACHE=${KUBECONFIG}
+    _kube_ps1_get_context_ns
+    return
+  fi
+
+  # kubectl will read the environment variable $KUBECONFIG
+  # otherwise set it to ~/.kube/config
+  local conf
+  for conf in $(_kube_ps1_split : "${KUBECONFIG:-${HOME}/.kube/config}"); do
+    [[ -r "${conf}" ]] || continue
     if _kube_ps1_file_newer_than "${conf}" "${KUBE_PS1_LAST_TIME}"; then
       _kube_ps1_get_context_ns
       return
@@ -83,26 +113,20 @@ _kube_ps1_load() {
 _kube_ps1_get_context_ns() {
 
   # Set the command time
-  KUBE_PS1_LAST_TIME=$(date +%s)
-
-  if [[ "${KUBE_PS1_DEFAULT}" == true ]]; then
-    local KUBE_BINARY="${KUBE_PS1_PLATFORM}"
-  elif [[ "${KUBE_PS1_DEFAULT}" == false ]] && [[ "${KUBE_PS1_PLATFORM}" == "kubectl" ]];then
-    local KUBE_BINARY="kubectl"
-  elif [[ "${KUBE_PS1_PLATFORM}" == "oc" ]]; then
-    local KUBE_BINARY="oc"
+  KUBE_PS1_LAST_TIME=$EPOCHSECONDS
+
+  KUBE_PS1_CONTEXT="$(${KUBE_PS1_BINARY} config current-context 2>/dev/null)"
+  if [[ -z "${KUBE_PS1_CONTEXT}" ]]; then
+    KUBE_PS1_CONTEXT="N/A"
+    KUBE_PS1_NAMESPACE="N/A"
+    return
+  elif [[ "${KUBE_PS1_NS_ENABLE}" == true ]]; then
+    KUBE_PS1_NAMESPACE="$(${KUBE_PS1_BINARY} config view --minify --output 'jsonpath={..namespace}' 2>/dev/null)"
+    # Set namespace to 'default' if it is not defined
+    KUBE_PS1_NAMESPACE="${KUBE_PS1_NAMESPACE:-default}"
   fi
-
-  KUBE_PS1_CONTEXT="$(${KUBE_BINARY} config current-context)"
-  KUBE_PS1_NAMESPACE="$(${KUBE_BINARY} config view --minify --output 'jsonpath={..namespace}')"
-  # Set namespace to default if it is not defined
-  KUBE_PS1_NAMESPACE="${KUBE_PS1_NAMESPACE:-default}"
-
 }
 
-# source our symbol
-kube_ps1_label
-
 # Build our prompt
 kube_ps1 () {
   local reset_color="%f"
@@ -111,7 +135,7 @@ kube_ps1 () {
   local cyan="%F{cyan}"
 
   KUBE_PS1="${reset_color}$KUBE_PS1_PREFIX"
-  KUBE_PS1+="${blue}$KUBE_PS1_DEFAULT_LABEL"
+  KUBE_PS1+="${blue}$(_kube_ps1_symbol)"
   KUBE_PS1+="${reset_color}$KUBE_PS1_SEPERATOR"
   KUBE_PS1+="${red}$KUBE_PS1_CONTEXT${reset_color}"
   KUBE_PS1+="$KUBE_PS1_DIVIDER"