kubelet failed to start after rebooting

Symptom:

kubelet failed to start after rebooting.

Env:

Ubuntu 18.04

Kubernetes 1.19

Root Cause:

From "journalctl -xefu kubelet", we can find out the root cause:

kubelet[11111]: F0430 xx:xx:xx.123456   11111 server.go:265] failed to run Kubelet: running with swap on is not supported, please disable swap! or set --fail-swap-on flag to false. /proc/swaps contained: 

Basically it means after rebooting, swap is on somehow.

Solution:

As mentioned in another blog "How to install a Kubernetes Cluster on CentOS 7", follow step 1.2 Disable Swap.

swapoff -a

And then comment out the swap entries in /etc/fstab.

After that, "systemctl status kubelet" should show kubelet is active (running).