Add Kubernetes context to your zsh prompt (for Agnoster theme, but can easily be adapted to different themes)

kubecontext.zsh

# INSTALLATION
# - Add the following function to your .oh-my-zsh/themes/agnoster.zsh-theme
# - Call prompt_kubecontext from build_prompt() as showed in the example below
#
#
# build_prompt() {
#  prompt_kubecontext
# }


prompt_kubecontext() {
  if [[ $(kubectl config current-context) == *"testing"* ]]; then
        prompt_segment green black "(`kubectl config current-context`)"
  elif [[ $(kubectl config current-context) == *"staging"* ]]; then
        prompt_segment yellow black "(`kubectl config current-context`)"
  elif [[ $(kubectl config current-context) == *"production"* ]]; then
        prompt_segment red yellow "(`kubectl config current-context`)"
  fi
}

but if you have to modify the prompt kube-ps1 is not useful, you can use below :

prompt_kubecontext() {
CTX=$(kubectx -c)
CNS=$(kubens -c)
  if [[ $CTX == *"tooling"* ]]; then
        prompt_segment green black "${CTX}:${CNS}"
  elif [[ $CTX == *"nonprod"* ]]; then
        prompt_segment yellow black "${CTX}:${CNS}"
  elif [[ $CTX == *"prod"* ]]; then
        prompt_segment red yellow "${CTX}:${CNS}"
  fi
}

FWIW I said that because the code you got above will likely add 300-500 ms to each of your prompts because you're calling kubectl so many times and not caching the result. kubectl is very slow and ideally you shouldn't run it on each prompt. kube-ps1 directly reads the config file and therefore is pretty darn fast.

That might be outdated ...

~ » time kubectl config current-context
aks1
kubectl config current-context  0.13s user 0.05s system 137% cpu 0.129 total

EDIT: Ah. I see it now ... the many conditionals in this particular example from OP definitely will benefit from running kubectl only ONCE