On Fri, Sep 16, 2022 at 11:48 AM Antonio Murdaca <run...@redhat.com> wrote:
> > > On Fri, Sep 16, 2022 at 11:38 AM Andrei Borzenkov <arvidj...@gmail.com> > wrote: > >> On Fri, Sep 16, 2022 at 11:11 AM Antonio Murdaca <run...@redhat.com> >> wrote: >> > >> > Hi, following >> https://systemd.io/AUTOMATIC_BOOT_ASSESSMENT/#how-to-adapt-this-scheme-to-other-setups >> I've been experimenting on a fedora system with >> systemd-boot-check-no-failures.service and the ability to have services run >> "after" boot-complete.target. The basic use case would just to have >> something that checks services are up and running, reach boot-complete if >> they are, and start other services afterwards. >> > I've taken from that blog this piece specifically: >> > ``` >> > To support additional components that shall only run on boot success, >> simply wrap them in a unit and order them after boot-complete.target, >> pulling it in. >> > ``` >> > So I've done the following with an example service and by enabling : >> > >> > # cat /etc/systemd/system/test.service >> > [Unit] >> > Description="Order after boot-complete.target, pulling it in" >> > After=boot-complete.target >> > Requires=boot-complete.target >> > >> > [Service] >> > Type=oneshot >> > ExecStart=/usr/bin/echo "Additional component that shall only run on >> boot success" >> > RemainAfterExit=yes >> > >> > [Install] >> > WantedBy=default.target >> > >> > # systemctl enable test.service systemd-boot-check-no-failures.service >> > Created symlink /etc/systemd/system/default.target.wants/test.service → >> /etc/systemd/system/test.service. >> >> This implicitly adds >> >> After=test.service >> >> to default.target >> >> > Created symlink >> /etc/systemd/system/boot-complete.target.requires/systemd-boot-check-no-failures.service >> → /usr/lib/systemd/system/systemd-boot-check-no-failures.service. >> > >> > # systemctl reboot >> > >> > Unfortunately, the above results in: >> > >> > systemd[1]: multi-user.target: Found ordering cycle on >> test.service/start >> > systemd[1]: multi-user.target: Found dependency on >> boot-complete.target/start >> > systemd[1]: multi-user.target: Found dependency on >> systemd-boot-check-no-failures.service/start >> >> And systemd-boot-check-no-failures.service is ordered after >> default.target but before boot-complete.target. So you have an >> ordering loop (test.service has to be both Before and After >> default,target). >> > > Right, I understand the cycle, the issue is that it is not > clear/straightforward to rely on systemd-boot-check-no-failures.service and > another service that should only be started after boot-complete.service as > w/o DefaultDependencies=No we introduce the cycle. > > >> >> > systemd[1]: multi-user.target: Found dependency on >> multi-user.target/start >> > systemd[1]: multi-user.target: Job test.service/start deleted to break >> ordering cycle starting with multi-user.target/start >> > >> > so what's the correct way to perform the mentioned "order [units] after >> boot-complete.target", if they cannot be pulled in through the usual >> default/multi-user targets? If I add DefaultDependencies=no to test.service >> it now appears to work w/o the dependency cycle. >> >> Yes, this is probably the only way. You may consider adding default >> dependencies explicitly if your service starts long running processes >> that need to be stopped on shutdown. >> > Re-adding dependencies on targets like shutdown for _any_ service that relates to boot-complete (in this case) seems weak too as it's not immediately clear why you need dd=no, I guess the relevant issue upstream describing something like this is https://github.com/systemd/systemd/issues/10210 > > Thanks for confirming this, although as somebody who followed > https://systemd.io/AUTOMATIC_BOOT_ASSESSMENT/#how-to-adapt-this-scheme-to-other-setups > what do you think about some official documentation/man page to help with > this? > > > -- > Antonio (runcom) Murdaca > Principal Software Engineer > B056 8311 87B3 DDEB 25B5 01AF CC5C 9A81 EDCA D821 > -- Antonio (runcom) Murdaca Principal Software Engineer B056 8311 87B3 DDEB 25B5 01AF CC5C 9A81 EDCA D821
