Renew lease

[marcovc]

This is a question, not a bug.

I have the following workflow (in pseudo code):

while true
    lease = etcdctl lease grant ttl
    if test
        etcdctl put --lease=lease key value
    else
        etcdctl del key
    endif
    sleep ttl/2

The idea is to have a key in the etcd2 meaning that a periodic test succeeds. The ttl exists to ensure that if the program is interrupted the key is cleared.

My ttl is small (like 5 seconds), meaning that I'm creating a new lease every 5 seconds. This seems to be hurting the etcd2 cluster performance, so I'm guessing this is not the intended use of leases.

What I would like to do is more like:

lease = etcdctl lease grant ttl
while true
    if test
        etcdctl put --lease=lease key value
    else
        etcdctl del key
    endif
    sleep ttl/2
    etcdctl renew lease <--- this would reset the lease ttl to the original value

But I can't find a command for renewing the lease. Also, I'm aware of the keepalive command, but I don't know how to use that with a test.

Can anyone point me in the right direction please?

Thanks!
Marco

[xiang90]

keepalive is a blocking call. probably you want something like keepalive --once, which only sends one renew call?

[marcovc]

Yes, that would work. It is not there yet, right?

[xiang90]

@marcovc no it is not. would like to help to add the feature?

[marcovc]

Sure, I'll do it. Thanks

[marcovc]

@xiang90, here is my attempt at this:

#8775

Never wrote go code before, so please look at it twice.

Thanks

[xiang90]

@marcovc thanks for the contribution. and go is really easy to get started :P

[marcovc]

Thank you for all the work. This was a simple one 😊