Support Kubernetes Lease API

[arianvp]

Kubernetes has something similar to consul sessions called the Lease API. Could we use it to simplify deployments in k8s so there is no dependency on consul?

[benbjohnson]

I didn't realize there was a Kubernetes Lease API. That's good to know. Yes, I think supporting that would be great. I'll tackle that once I get the project stabilized and tested. Thanks!

[phillamb168]

Following

[benbjohnson]

@phillamb168 Just as a heads up there should be a "Subscribe" button on the right side of the PR if you want to get future notifications.

[arianvp]

By the way here is the upstream example:

https://github.com/kubernetes/client-go/blob/v0.25.2/examples/leader-election/main.go

It uses a built-in leader elector loop which is maybe not what you want. So probably have to peek into https://github.com/kubernetes/client-go/blob/2fd4aac19007b97ef5b22d045b5615e2094200a1/tools/leaderelection/leaderelection.go#L243 and see how to hook it into litefs' loop

[benbjohnson]

@arianvp Thanks for the example code. It looks like the loop is handled by the Kubernetes client and acquire() and renew() isn't accessible. I'll need to refactor the LiteFS code a bit so it can externalize the loop instead of handling it itself.

[arianvp]

acquireOrRenew is implemented in terms of only public functions. So perhaps it's worth looking at its impl and mimicking it if you want to keep your own loop

https://github.com/kubernetes/client-go/blob/2fd4aac19007b97ef5b22d045b5615e2094200a1/tools/leaderelection/leaderelection.go#L317

But reusing the kubernetes loop might probably be more robust.

[casidiablo]

Just wanted to give a more visible thumbs up to this feature request.

I know people also want etcd and Zookeeper, and you mentioned this is lower priority, but at least I thought I would ask in case priorities have changed or if you have new opinions about this.