Re: [systemd-devel] What is the recommended way of announcing a TCP port?
On Tue, Jun 15, 2021 at 1:45 AM Mantas Mikulėnas wrote: > If you only care about processes on the same system – why not put the > actual socket in /run, as an AF_UNIX socket? That's mostly what /run is for. > I thought of that, but Prometheus cannot scrape AF_UNIX addresses. Thanks though, /ji > On Tue, Jun 15, 2021, 04:18 John Ioannidis 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 >> > ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] What is the recommended way of announcing a TCP port?
On Mon, Jun 14, 2021 at 9:29 PM Kevin P. Fleming 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 > 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 > ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] What is the recommended way of announcing a TCP port?
If you only care about processes on the same system – why not put the actual socket in /run, as an AF_UNIX socket? That's mostly what /run is for. On Tue, Jun 15, 2021, 04:18 John Ioannidis 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 > ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] What is the recommended way of announcing a TCP port?
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. On Mon, Jun 14, 2021 at 9:17 PM John Ioannidis 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 ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel
