kubectl-daemons

kubectl-daemons

Intro

kubectl-daemons is a kubectl plugin to help with daemonset work. When running a kubernetes infrastructure, it is common to do lots of work with deamonsets, but the tools are optimized for other workflows where node names aren't particularly important.. With daemonsets, you often know a node and a DS you care about, and this plugin lets you focus on that.

Previously you'd do things like:

kubectl get pods -o wide | grep <daemonset> | grep <node>
kubectl describe pod <pod_from_above>
kubectl delete pod <pod_from_above>
kubectl get pods -o wide | grep <daemonset> | grep <node>
...

Or maybe:

kubectl get pods --field-selector spec.nodeName=<node>
kubectl describe pod <pod_from above>
kubectl delete pod <pod_from above>
kubectl get pods ---field-selector spec.nodeName=<node>
...

No more using a long get command to find the pod name, and having to keep track of it! Just specify the DS and the node:

kubectl d describe <daemonset> -N <node>
kubectl d delete <daemonset> -N <node>
kubectl d logs <daemonset> -N <node>

General Usage

Get pods from a daemonset:

kubectl d get <daemonset>

Or get the pod from a daemonset on a specific node

kubectl d get <daemonset> -N <node>

Or get all daemonset-related pods on a node. I think of this as the equivalent of asking systemd to list all services on a node. :)

kubectl d get -N <nodename>

Or you can delete the pod from a daemonset on a specific node

kubectl d delete <daemonset> -N <nodename>

You can do logs as well:

kubectl d logs <daemonset> -N <node>

NOTE: -N is required here.

You can describe pods:

kubectl d describe <daemonset> [-N <node>] # node optional

You can even exec:

kubectl d exec <daemonset> -N <node> -- echo "Hello world"

Or interactively:

kubectl d exec <daemonset> -N <node> -it -- /bin/bash

And you can list all daemonsets on a node:

kubectl d list <node>

Installing

The easiest way to install, right now, is to grab the right build from our releases page, and drop the binary (kubectl-d) in your PATH.

If you get an error like "macOS cannot verify this app..." see this page.

We've submitted this plugin to Kraw, and will update these installation instructions once that's merged.

Building from source

The quick-n-easy way to build is:

go build -o kubectl-d

Then stick kubectl-d somewhere in your path.

Thanks

A huge thanks to Benjamin Muschko's Writing your first kubectl plugin blog post and associated GH repo. This was invaluable in getting me up and running.

FAQ

Why not just write a simple shell wrapper?

For many reasons. First, I had that, and it's quite slow. You end up doing more queries than you need, and if your API servers are on the other side of privatelinks, it can get quite slow.

Second, I wanted a good excuse to learn some golang and get better at Kube internals.

Aren't there already other plugins that do this?

Not that I could find!

Can I contribute?

Sure, send a pull request!

Why did you end up re-implementing so much kubectl formatting code?

Trust me, I didn't want to. Unfortunately kubectl plugins aren't really "plugins". They're standalone binaries that kubectl executes for you. So you can use whatever is in the k8s libraries, but various things kubectl does like formatting describe output, or various calculated fields, are note exposed as functions other code can call.

Ideally, plugins would be a library that could hook into various stages within kubectl and allow you to not have to implement so much yourself, but it turns out that's not how kubectl plugins work.

Will you be submitting this to Krew?

Yes! That'll happen very soon.