[systemd-devel] Submitting a service activation to remote mounts success

[Silvio Knizek]

Am Dienstag, dem 06.02.2024 um 16:15 +0100 schrieb Thomas HUMMEL:
> Hello,
>=20
> I'm using systemd-239-74 on RHEL 8.8 EUS.
>=20
> I was wondering if one can express the following :
>=20
> start some service *only and only if/when* all remote mounts (ex: nfs,=
=20
> some parallel fs) has *succeeded*, taking into account it may take some=
=20
> time for some mount (some fs clients just live curl | sh themselves at=
=20
> start !) to finish (which seems to exlude usage of=20
> AssertPathIsMountPoint for instance, as it would not wait, or would it ?)
>=20
> I have no auto option in the fstab for those fs and they use the _netdev=
=20
> option
>=20
> Obvisouly I could statically list all the mounts units as an ordering=20
> dependency but this is not what I was looking for as there are namy (and=
=20
> I'm not even sure - see below - it it would be enough)
>=20
> Exploring this question I stumbled upon the following points :
>=20
> my understanding is that:
>=20
> 1. remote-fs.target special target is pulled in by multi-user.target and=
=20
> is added by systemd-fstab-generator as a Before=3D ordering dep to all=
=20
> remote .mount units
>=20
> -> I also see a remote-fs.target has a Requires=3D<remote-mounts>=20
> activation dep : I probably missed it in the doc but I don't see this=20
> listed in neither implicit nor default dep : where does it come from ?
>=20
> 2. Before=3D/After=3D refer, in the case of service units, to when the un=
it=20
> has "finished starting up", this being defined by "when it returns=20
> failed or success", which is dependent of the Type=3D of the service
>=20
> Is this understanding correct ?
>=20
> But when the unit is of type mount : what's the semantic of Before/After=
=20
> ? (I don't think I saw it in the doc neither)
>=20
> What's the meaning/use of Type=3Dnone in a .mount unit ?
>=20
> My experience is that the mount may fail and remote-fs.target will still=
=20
> be reached, even if one replace Requires with BindsTo, correct ?
>=20
> So success or failure of the mount process does not seem to be involved=
=20
> in the ordering dep, or does it ?
>=20
> Thanks for your help

Hi Thomas,

RequiresMountsFor=3D should be your friend. It just takes a space-
separated list of paths and does all the other stuff by itself.

Another options would be to switch to x-systemd.automount in fstab for
the network shares, so they will be mounted on first access, not
necessary during early boot when there is no network.

BR
Silvio