Hi, On 12/18/24 19:38, Jonathan Dowland wrote:
I would also like to see this. Perhaps it's because the maintainers don't want to close the door to alternative init systems, by making their package depend on systemd features?
Most likely it is because BSD does not have systemd, and quite a lot of Postfix installations, especially larger ones, run on BSD.
Postfix's "master" process effectively implements an orchestrator for a microservice architecture, similar to what systemd does. This could be replaced by systemd by writing a generator that creates units from master.cf.
Simply converting the default master.cf to unit files and shipping these as default would still be a massive regression, because it would obsolete a lot of documentation on how the Postfix system is orchestrated and how to integrate new services like clamav and spamassassin or to deliver to courier.
All of these recipes would become "instead of this one line in master.cf, you need to create a service unit, socket unit and possibly timer unit." My expectation would be that the next sentence would be "Please refer to the systemd documentation on how to do that.", and while the systemd documentation is exhaustive, it is significantly less targeted to the operation of mail systems than the manual page for the master.cf configuration file format.
Specifically, changes to master.cf are frequently of the form "make this service local-only, and instead expose a copy of it with a special instance name that makes it write to a special queue." As a text file modification, that is easy, but replicating this with systemd units is going to be a complexity nightmare. Do we want to use template units? Drop-in directories? Templated drop-ins?
I don't see this happening without upstream support. However, upstream has little incentive to do so: they currently have an orchestrator that works, is completely controlled by them and not subject to another project's interface changes (rare as they may be), and is free to make the assumption that the services being started are vaguely related to mail delivery.
If they were to ship unit files, they'd end up in the same documentation nightmare as we would if we were to start doing so, and if they create a generator and start using systemd as the controlling process, they would not gain anything, because neither can they drop their own orchestrator (so this creates additional testing surface, as their services would now need to implement *two* service manager protocols), nor would that directly provide any additional functionality.
Simon
