In deployments with more than one frontend running it would be nice to be able to run pagure-events.service in a way that it doesn't cause duplicate actions to be ran for single message received.

Separate instances of pagure-events could take advantage of shared database to synchronize themselves. Some alternative ideas:

1. Before listening to fedmsg messages pagure-events would acquire exclusive database lock. Should the service/host go down, DB server would release the lock and let the other service acquire it and start receiving messages.

2. You could log in database all messages processed and enforce unique constraint on massage id. All running services would then try to update database in reaction to the massage received, and in the same transaction insert log entry confirming processing message. Only one service would be able to commit transaction, other transactions would be aborted with unique constraint violation.