Kured¶

KUbernetes REboot Daemon: https://github.com/weaveworks/kured

https://learn.microsoft.com/en-us/azure/aks/node-updates-kured

To protect clusters, security updates are automatically applied to Linux nodes in AKS. Some of these updates require a node reboot to complete the process.

With kured, a DaemonSet is deployed that runs a pod on each Linux node in the cluster. These pods in the DaemonSet watch for existence of the /var/run/reboot-required file, and then initiate a process to reboot the nodes.

cli¶

helm install kured stable/kured --namespace kured --set extraArgs.reboot-days="Mon\,Tue"

check logs¶

kubectl -n <namespace> logs <kured-pod-name>

Result

"Reboot schedule: SunMonTueWedThuFriSat between 00:00 and 23:59 UTC"

reboot schedule¶

--start-time: string, schedule reboot only after this time of day (default "0:00")
--end-time: string, schedule reboot only before this time of day (default "23:59:59")
--reboot-days: strings, schedule reboot on these days (default [su,mo,tu,we,th,fr,sa]
```
--reboot-days=mon,tue,wed,thu,fri
--start-time=9am
--end-time=5pm
--time-zone=America/Los_Angeles
```
Times can be formatted in numerous ways, including 5pm, 5:00pm, 17:00, and 17.

configuration¶

https://kured.dev/docs/configuration/

In values.yaml

extraArgs:
  start-time: "0:00"
  end-time: "23:59"
  reboot-days: "Mon,Tue"

becomes

/usr/bin/kured ... --start-time="0:00" --end_time="23:59" --reboot-days="Mon\,Tue"

error: DaemonSet.apps "kured" is invalid: spec.selector: ... field is immutable¶

https://github.com/kubereboot/kured/issues/610

Solution: uninstall the release and install it again - cannot simply upgrade