Is there a way to run a job only once upon machine reboot in Kubernetes?
Thought of running a cronjob as static pod but seems kubelet does not like it.
Edit: Based on the replies, I'd like to clarify. I'm only looking at doing this through native Kubernetes. I'm ok writing a cronjob in Kubernetes but I need this to run only once and upon node reboot.
Not sure your platform.
For example, in AWS, ec2 instance has user_data (https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/user-data.html)
It will run commands on Your Linux/Windows Instance at Launch
You should be fine to find the similar solutions for other cloud providers or on-premise servers.
Consider using CronJob for this. It takes the same format as normal cron scheduler on linux. Besides the usual format (minute / hour / day of month / month / day of week) that is widely used to indicate a schedule, cron scheduler also allows the use of @reboot. This directive, followed by the absolute path to the script, will cause it to run when the machine boots.
If I understand you correctly you should consider using DaemonSet:
A
DaemonSetensures that all (or some) Nodes run a copy of a Pod. As nodes are added to the cluster, Pods are added to them. As nodes are removed from the cluster, those Pods are garbage collected. Deleting aDaemonSetwill clean up the Pods it created.
That way you could create a container with a job that would be run from a DaemonSet.
Alternatively you could consider DaemonJob:
This is an example
CompositeControllerthat's similar to Job, except that a pod will be scheduled to each node, similar toDaemonSet.
Also there are:
Kubebuilder is a framework for building Kubernetes APIs using custom resource definitions (CRDs).
and:
Metacontroller is an add-on for Kubernetes that makes it easy to write and deploy custom controllers in the form of simple scripts.
But the first option that I have provided would be easier to implement in my opinion.
Please let me know if that helped.