Kubernetes Explained Simply: Data Extraction With JSON Path [Part 8]

kubectl

 can pull a lot of data about our deployments and pod.  Most of the time, we humans are the recipients of that information, and 

kubectl

 obliges by nicely formatting things in pretty tables.

Ah yes, I see the pod is now called "... FIXME ..."

In my experience, the very next command that I run  needs that auto-generated Pod ID, something like 

kubectl logs

 or 

kubectl exec

.  The first couple of times, you'll use the pasteboard – highlight the pod name with your mouse, 

Cmd-C

, and you're off to the races.  By the third, fourth, or fiftieth time, however, you'll be wishing for a better way.

This is UNIX, right?  World-famous for its text processing capabilities?  We got this covered.

Well, it does work, even if it is a bit awkward, and a lot to type.

kubectl

 has lots of different output formats at its disposal; the default one just happens to be such a good fit for human eyes that we don't always go looking for others.  We can change the output format via the

-o

 flag.  For example, we can dump all of the pods in JSON format, and then use 

jq

 to parse through it:

What happens if we don't have 

jq

 available to us?  This may surprise you, what with this being a blog post about 

kubectl

 tricks and all, but 

kubectl

 can do this natively...

It's called JSON Path, and it essentially lets you embed simple 

jq

 scripts into your 

kubectl

 call, directly:

(Just remember to enclose the variable reference in balanced curly braces.)

JSON Path has its fair share of fanciness, including filters.  For example, if you have a pod with lots of constituent containers, you can extract information about a subset like this:

Here we're identifying which containers in our pod are running the upstream 

redis

 image.  Neat!

Also published here.