Support running multiple, isolated instances of `swarm-cronjob` within a single Docker Swarm cluster

[kgilden]

Description

It seems that swarm-cronjob executes jobs found from any stack running within the same Docker Swarm cluster. Would it be possible to somehow limit swarm-cronjob to only read in cronjobs from only the same stack in which it is deployed?

We use Docker Swarm to host multiple versions of our application within the same cluster for development. We're observing that each swarm-cronjob instance executes cronjobs of all stacks. So if for example there are 5 version of our app running, then each cronjob is run 5 times. We want to keep running multiple instances of swarm-cronjob so that the dev environments would be as close as our production environment.