Useful tools for Kubernetes

Most people using Kubernetes extensive have already defined alias k=kubectl and are using tools like kubectx. As someone really lazy though, I have found/developed a few less common tools to help work with Kubernetes efficiently.

kubectl apply from clipboard

This relies on zsh, and uses the zle to define a custom command.

function zle_apply {
  LBUFFER=" cat <<EOF | kubectl apply -f -
$(xclip -se c -o)
EOF"
  CURSOR=31
}
zle -N zle_apply; bindkey "^k" zle_apply

This defines a function and binds it to Ctrl+k.

This will get us one "enter" away from applying whatever we have in our clipboard. We could just apply it in a single hotkey, but that seems a bit reckless.

The cursor is also conveniently moved to just after the -f - in case we want to set any other flags.

Picking pod names with fzf

fzf is a "command line fuzzy finder", useful for... finding things.

Here, we can use it to find a Pod name, and insert it into our current command line:

# First, define a function that sends all pods to `fzf`.
# Once it picks a row, extract the 1st column (the pod name).
function fkp () {
  pods=$(set -o pipefail; kubectl get pods --no-headers ${@})  || return 1
  fzf --nth 1,2 <<< $pods | awk '{print $1}'
}
# Now define a ZLE function that just calls this and inserts the result into our buffer
function zle_fkp {
  res=$(fkp) || return 1
  LBUFFER="${LBUFFER}${res} "
  zle reset-prompt
}
# Finally, bind it to Alt+k
zle -N zle_fkp; bindkey "^[k" zle_fkp

Its easier show this:

This avoids typing part of a command, realizing we need a pod name, running another command, selecting the name, and copying it over. This could be generalized to other resources as well, but I operate with pods a lot.

Grepping YAMLs

kubectl grep is a handy tool for grepping through Kubernetes YAMLs, and has grown beyond YAML.

For example, summarizing all resources:

$ helm template istio/istiod | k grep -s
PodDisruptionBudget/istiod.default
ServiceAccount/istiod.istio-system
ConfigMap/istio.default
ConfigMap/istio-sidecar-injector.default

Searching for a literal within objects, and stripping fields that are not commonly needed (managedFields, last-applied-configuration, etc):

$ kubectl get pods -A -oyaml | k grep -r runAsNonRoot -N
apiVersion: v1
kind: Pod
metadata:
  annotations:
...

Log Helpers

log-helper is like grep, but instead of filtering matches, it highlights them.

Another nice feature is the -k flag - replacing all IP addresses with the name of the Kubernetes resource it refers to - highlighting it in the process, of course.

So something like remoteAddr=10.36.2.4 becomes remoteAddr=shell-dc477d7c-k88dm. Much better.

Finalizers

finalizers is a two-for-one - a nice tool to find "stuck" resources, and a fitting description for how I feel about finalizers.