Question: Fluent Bit compatibility with Kubernetes versions

[hahakiki2025]

Hi team,

I’d like to confirm whether Fluent Bit provides any documentation or guarantees regarding compatibility with different Kubernetes versions.

I checked the Fluent Bit 4.0 documentation but couldn’t find any mention of Kubernetes version compatibility. From my perspective, the Kubernetes filter plugin may be affected by Kubernetes version changes, since it communicates with the Kubernetes API server to retrieve metadata.

My questions are:

• Does Fluent Bit upstream test against new Kubernetes releases to ensure compatibility?
• Is there an official matrix or documentation that tracks which Kubernetes versions are verified to work with each Fluent Bit release?

Thanks!

[patrick-stephens]

We do not officially test in OSS multiple variants but there are integration tests. There are a lot of configuration options multiplied by plugin usage so I'd always say test your usage or use an enterprise provider to satisfy your needs: https://fluentbit.io/enterprise/

Here's my answer from your slack thread too!

Short answer, yes it is compatible.

Longer answer is that if you're using Linux then there's only a few things Fluent Bit will be reliant on:
Running the container, if your K8S distribution cannot do this then you have bigger problems.
Mounting kubelet log files into the container to tail.
Using the K8S rest API to get pod metadata, been stable for a while!

You may be using the systemd input plugin in which case you need compatible versions on the host and in the container but typically it's backwards compatible.

You may also be using the kubernetes event plugin but again this is just the rest API.

The helm chart has various configurable options so you may be using a feature that requires a specific K8S version, e.g. PSP, but that's fully configurable by you.