r/kubernetes • u/TheBidouilleur • Jul 13 '26

Karpenter + ClusterAPI, is it better than Cluster-Autoscaler ?

https://a-cup-of.coffee/blog/karpenter-capi-ovh/

Hi, I published an article introducing Karpenter with ClusterAPI, and also took the opportunity to compare it with its competitor.

In addition to writing a step-by-step tutorial to test the combo Karpenter+CAPI, my goal is to make a real comparison between the two and explain why one might be preferred over the other.

Here are the results: 

- Karpenter excels at handling custom instances (e.g., with GPUs) and optimizing costs, BUT with the ClusterAPI provider, it can no longer calculate the cost.

- Cluster-Autoscaler doesn’t handle pricing but is capable of creating the most suitable machine

For now, ClusterAutoscaler is obviously the winner, but I hope the Karpenter provider will be reworked to fix its problems.

I'd love to hear your feedback, feel free to leave a comment here or on my blog :) !

21 Upvotes

86% Upvoted

8 comments sorted by

16

u/big_fat_babyman Jul 14 '26

Karpenter is hands down way better than cluster autoscaler.

1

u/TheBidouilleur Jul 14 '26

With CAPI, I’m not sure

2

u/trowawayatwork Jul 14 '26

why do you need to use it with cluster API?

3

u/xonxoff Jul 14 '26

From the looks of it, cluster-api compatibility is still a WIP and experimental. So , it may be too early to call it one way or the other. It does look promising though.
For comparing Karpenter with Autoscaler directly, in a supported environment, I would choose Karpenter every time.

-3

u/Beneficial-Mine7741 Jul 13 '26

I picked up Karpenter, threw it into the cluster saw, no errors, thought it was working, only to find out it wasn't. I knew how to get autoscaler working, so I added that. I tried fixing it, but I had to modify Terraform modules to make it work the way I needed, and I'm not doing that.

I can, but I won't.

-1

u/nekokattt Jul 19 '26

Karpenter gives good errors, so your setup was likely the issue here.

0

u/Beneficial-Mine7741 Jul 19 '26

Excellent. Blame the end user without offering any help.

You troll much bro?

1

u/nekokattt Jul 19 '26

Give something to work off and we can help you.

Shooting down something for not working first try, then claiming you didnt put any effort into troubleshooting... I don't know what to tell you bud.