Have you ever wondered about running kubectl commands in parallel for some of your clusters? You must have written custom shell scripts or Golang scripts to do so.

Fortunately, a tool to run commands in parallel now exists, Thanks to Ahmet Alp Balkan 🙏

Check out the GitHub repo, and don’t forget to ⭐️ the repo :)

kubectl-foreach Is a tool that allows users to run a kubectl command in one or more contexts (clusters) in parallel. This can be very useful when you need to perform an action on all of the resources in given contexts/clusters, such as gathering information, scaling them up or down, rolling out an update, or applying a configuration change.

Installing kubectl-foreach

• Download the binary from the release pages of the project based on your Operating system and architecture.

• Install using the Krew kubectl plugin manager

kubectl krew install foreach

• Build from scratch

go install github.com/ahmetb/kubectl-foreach@latest

Let's try it out

• Check versions on all the clusters at once

    kubectl foreach -- version
  

Basically, whatever you write -- will be your ARGS for kubectl commands

It will now show you the following prompt,

Will run command in context(s):
  - civo-1
  - civo-2
  - docker-desktop
Continue? [Y/n]:

Once you type Yyou will see the equivalent kubectl version output for all the clusters,

Continue? [Y/n]: Y
docker-desktop | WARNING: This version information is deprecated and will be replaced with the output from kubectl version --short. Use --output=yaml|json to get the full version.
docker-desktop | Client Version: version.Info{Major:"1", Minor:"25", GitVersion:"v1.25.2", GitCommit:"5835544ca568b757a8ecae5c153f317e5736700e", GitTreeState:"clean", BuildDate:"2022-09-21T14:33:49Z", GoVersion:"go1.19.1", Compiler:"gc", Platform:"darwin/arm64"}
docker-desktop | Kustomize Version: v4.5.7
docker-desktop | Server Version: version.Info{Major:"1", Minor:"24", GitVersion:"v1.24.0", GitCommit:"4ce5a8954017644c5420bae81d72b09b735c21f0", GitTreeState:"clean", BuildDate:"2022-05-03T13:38:19Z", GoVersion:"go1.18.1", Compiler:"gc", Platform:"linux/arm64"}
civo-2 | Client Version: version.Info{Major:"1", Minor:"25", GitVersion:"v1.25.2", GitCommit:"5835544ca568b757a8ecae5c153f317e5736700e", GitTreeState:"clean", BuildDate:"2022-09-21T14:33:49Z", GoVersion:"go1.19.1", Compiler:"gc", Platform:"darwin/arm64"}
civo-2 | Kustomize Version: v4.5.7
civo-2 | Server Version: version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.6+k3s1", GitCommit:"418c3fa858b69b12b9cefbcff0526f666a6236b9", GitTreeState:"clean", BuildDate:"2022-04-28T22:16:18Z", GoVersion:"go1.17.5", Compiler:"gc", Platform:"linux/amd64"}
civo-2 | WARNING: This version information is deprecated and will be replaced with the output from kubectl version --short. Use --output=yaml|json to get the full version.
civo-1 | Client Version: version.Info{Major:"1", Minor:"25", GitVersion:"v1.25.2", GitCommit:"5835544ca568b757a8ecae5c153f317e5736700e", GitTreeState:"clean", BuildDate:"2022-09-21T14:33:49Z", GoVersion:"go1.19.1", Compiler:"gc", Platform:"darwin/arm64"}
civo-1 | Kustomize Version: v4.5.7
civo-1 | Server Version: version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.6+k3s1", GitCommit:"418c3fa858b69b12b9cefbcff0526f666a6236b9", GitTreeState:"clean", BuildDate:"2022-04-28T22:16:18Z", GoVersion: civo-2 | WARNING: version difference between client (1.25) and server (1.23) exceeds the supported minor version skew of +/-1
"go1.17.5", Compiler:"gc", Platform:"linux/amd64"}
civo-1 | WARNING: This version information is deprecated and will be replaced with the output from kubectl version --short. Use --output=yaml|json to get the full version.
civo-1 | WARNING: version difference between client (1.25) and server (1.23) exceeds the supported minor version skew of +/-1

Note: you can disable the prompt by passing the -q flag, you can also set the environment variable KUBECTL_FOREACH_DISABLE_PROMPTS=true to true so that the command won't prompt again

• the previous command showed output from docker-desktop ,civo-1 , civo-2 What if I only want to see the outputs of civo clusters?

For that, you can supply a regex of your choice, for example,

$ kubectl foreach /civo/ -- get ns
Will run command in context(s):
  - civo-1
  - civo-2
civo-1 | NAME STATUS AGE
civo-1 | default Active 44m
civo-1 | kube-system Active 44m
civo-1 | kube-public Active 44m
civo-1 | kube-node-lease Active 44m
civo-2 | NAME STATUS AGE
civo-2 | kube-system Active 34m
civo-2 | default Active 34m
civo-2 | kube-public Active 34m
civo-2 | kube-node-lease Active 34m

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