Eventually, you'll write a super handy script for interacting with Kubernetes – I have no doubt. Wouldn't it be stellar if you could that your script was officially part of the repertoire? pretend kubectl You can! is a , in the same fashion as . When you call it with a sub-command it doesn't intrinsically recognize, it tells you: kubectl multi-call binary git $ kubectl fu unknown command "fu" for "kubectl"

Did you mean this?
	run
	cp

Run 'kubectl --help' for usage. Error: Before it spits out the usage screen, however, does a bit of spelunking through each component directory in your , looking for an executable file named . We can use this to our advantage: kubectl $PATH kubectl-$COMMAND $ /Users/jhunt/bin:/usr/bin:/bin:/usr/sbin:/sbin

$ cat ~/bin/kubectl-fu $ kubectl fu
the kubernetes is strong with this one... echo $PATH #!/bin/sh echo "the kubernetes is strong with this one..." It doesn't matter what you write your program in; hack up some Bash, compile some Go or Rust, even write it in Perl or Python! As long as it is in , and has the executable bit set, you can pretend to be a core CLI author! $PATH Here's a more potent and useful example, which uses a bit of Go magic to handle the base64 encoding that Kubernetes puts on all of its Secrets. If you store secrets in Kubernetes, they get encrypted at rest, and are returned by the API encoded using the Base 64 scheme. While the , using the encoded data is a bit of a pain. particulars of the algorithm are interesting $ kubectl creds -o = aXQncyBhIHNlY3JldCB0byBldmVyeWJvZHku get secret jsonpath '{.data.password}' Luckily, we can use Go templates to format data we get from the API. What's more, the template language has the ability to decode base64-encoded data, natively! Here's a first attempt at extracting the data: $ kubectl secret creds -o template='{{.data.password | base64decode }}' 's a secret everybody. get it to That's mighty useful. If we package it up as the new sub-command, it gets 10x more useful! kubectl decode $ cat ~/bin/kubectl-decode kubectl get secret -o template= $ chmod 0755 ~/bin/kubectl-decode

$ kubectl decode creds
it #!/bin/sh exec '{{.data.password | base64decode }}' " " $@ 's a secret to everybody. Also seen here .

Stellar

Super

Write Your Own Kubernetes Sub-Command [Part 9]

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