Please consider making the zed daemon activated on demand

[Christian Ehrhardt ]

Hi,
currently if one wants most common FS tools to be able to mount them to e.g. mount them "just in case" or when considering a more capable base image or install CD then there is the problem that installing "zfsutils-linux" pulls in "zfs-zed" as a recommends.

Having it on disk would be ok, but IMHO there is no reason this daemon needs to run until the first ZFS element is created.

● zfs-zed.service - ZFS Event Daemon (zed)
   Loaded: loaded (/lib/systemd/system/zfs-zed.service; enabled; vendor preset: enabled)
   Active: active (running) since Thu 2018-11-29 16:09:04 UTC; 3min 26s ago
     Docs: man:zed(8)
 Main PID: 2968 (zed)
    Tasks: 2 (limit: 546)
   Memory: 436.0K
   CGroup: /system.slice/zfs-zed.service
           └─2968 /usr/sbin/zed -F

Nov 29 16:09:04 disco-zfstest systemd[1]: Started ZFS Event Daemon (zed).
Nov 29 16:09:04 disco-zfstest zed[2968]: ZFS Event Daemon 0.7.9-3ubuntu6 (PID 2968)
Nov 29 16:09:04 disco-zfstest zed[2968]: Processing events since eid=0

People in general would want the number of default running services low.
Further than the general "not too much default daemons" there are a few issues like [1] which makes this worse if one is affected.

There is no related upstream feature yet that I'd know of, nor did I find a trivial way to e.g. match a systemd unit Condition (which also is only evaluated only once, so it would miss later zfs creation) or a socket (what would it wait for).

I wanted to ask here if you'd have more/better ideas or if we should directly file this upstream and then link that bug here?

[1]: https://github.com/zfsonlinux/zfs/issues/7995

[Randall Leeds (randall-leeds)]

It seems like this may no longer be the case. In fact, a recent upgrade on my system removed zfs-zed, which seems like maybe a mistake since the zsys-setup script still seems to expect it.

[Randall Leeds (randall-leeds)]

My mistake, it seems the latest import just introduced a typo and the zfsutils-linux package now depends on the (non-existent) fs-zed package, rather than zfs-zed. I'll report that as a separate bug. This one is still valid.