On Tue, Oct 29, 2024 at 4:50 AM Adam Nielsen <a.nielsen@xxxxxxxxxxx> wrote:
Hi all,
I'm having some problems getting a systemd unit to start during system
boot. Can anyone advise what I'm doing wrong?
The service starts fine if I run `systemctl start myservice`, the issue
is that it fails to start during boot.
The service runs off a network share, so if it starts too early in the
boot process the share is not mounted and it fails for that reason and
systemd does not try to restart it later, despite the unit file saying
to restart forever.
Units are only restarted when they are already running and their daemon process fails; they're never "retried" when conditions or dependencies change when the unit never reached 'starting' at all.
If systemd itself is responsible for the mount (i.e. there is a fstab entry or a .mount unit), then your service can have a dependency on it, and can be ordered to wait until the mount succeeds (either using explicit Requires= & After= on the .mount, or the combined RequiresMountsFor= that you already have).
(The RequiresMountsFor would internally expand to [Unit] Requires=mnt-share.mount After=mnt-share.mount, or something along those lines.)
But if the mount just randomly shows up by some external means, that won't happen – the .mount unit didn't exist at boot time, the dependency wasn't met and that's the end of story. In this case, you have to do the *opposite* – if you want systemd to react to the event of the mount showing up, then your service has to be a dependency of the mount.
Even externally established mounts have virtual .mount units in systemd, so if you want your service to be started by the *event* of /mnt/share being mounted, [Install] WantedBy=mnt-share.mount would achieve that.
--
Mantas Mikulėnas
