GCP GKE cluster node throws {"unmanaged": {"fs.aio-nr": "2272", "net.ipv4.tcp_fastopen_key"

Question

I recently installed on GKE Botkube and it started showing error of does anyone have any idea how to approach that issue or what would that mean ? I've read on wikipedia on how fastopen helps to make client-server connection quicker on second re-try skiping the 3 way syn-ack but what could this error mean ?

Answer 1

The messages you are seeing are the TCP Fast Open (TFO) encryption keys sent by the GKE node, and I'm assuming they are being marked as an error by Botkube because every time a new encryption key is generated, it's done by modifying a Linux Kernel parameter using the Sysctl command, which might be a trigger.

As far as I understand, this is the normal behavior for TFO, and it is safe to disregard these messages.

A very good explanation on how the encryption keys for TFO are generated can be found on this Serverfault question.