Scale Group size down to 0

[wongwill86]

Hello,

There are cases in which I would like a group to be scaled down to 0, i.e. for autoscaling. but right now i think https://github.com/docker/infrakit/blob/master/pkg/plugin/group/group.go#L344 is preventing me from doing that.

Group swarm-workers at 0 instancesCRIT[10-05|22:23:28] error executing                          module=main cmd=infrakit err="Allocation must not be blank" fn=main.main
Allocation must not be blank

I also tried using destroy-instances but all i get is:

infrakit group destroy-instances swarm-workers
Initiated.

but the instances are never destroyed.

obviously i can destroy the group altogether but when i want to scale back up again i would then have to recommit the groups file which isn't ideal.

It would be nice if we can scale the group down to 0.

Thanks!

[kaufers]

Also, can we commit a group of 0 size?

The use case is that our scripts always want to commit a workers group, even if it is of size 0. We would like the group to exist so that we could statically define in in a LB configuration (ie, we want to the config to always include group/workers and group/managers in the backend nodes, even if workers has 0 members).