On Mon, Jun 14, 2021 at 9:29 PM Kevin P. Fleming <ke...@km6g.us> wrote:
> You might consider having systemd itself create the listening sockets > and then pass them into the service; if you did that, then systemd > would already know the port number that was allocated for the socket. > > I can't; a .socket unit gets activated, and subsequently starts its corresponding service, when the first connection is made. The primary purpose of the service is not to serve data over that socket; the socket is there for scraping metrics. Thanks though, /ji > On Mon, Jun 14, 2021 at 9:17 PM John Ioannidis <systemd-de...@tla.org> > wrote: > > > > I have an instanced service that gets started and stopped by another > service: alice.service runs the equivalent of systemsctl start > alice@foo.service, systemctl start alice@bar.service, systemctl stop > alice@cat.service, and so on. > > Each of the instanced services runs a little http service so its status > can be monitored, metrics scraped, etc. The tcp port on which that service > runs is just whatever the kernel allocated. I want to export that port > number so other processes can find it and use it, for example, by doing the > equivalent of systemctl list-units | grep alice@ so they find which > instances are actually running, and then going about finding the > corresponding ports. > > > > I can think of a number of ad hoc ways: > > > > * they can write the port number in a file like /run/alice/foo.port, > /run/alice/bar.port, and whoever is interested can go read those files, in > the same way that we use .pid files. > > * They can use systemd-notify to export it as "Status" > > * Using a service discovery mechanism would be an overkill, especially > since whatever is actually talking to those ports is on the same host as > the services themselves, but that's also a possibility. > > > > Is there a systemd-native way of accomplishing this? It would be nice if > it were possible to have user-defined properties that could be set with > systemctl set-property, but that is not the case. > > > > Thanks > > > > /ji > > _______________________________________________ > > systemd-devel mailing list > > systemd-devel@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/systemd-devel >
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