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#76998
Guix Home leaves user shepherd on logout, starts new instance on login
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Your bug report
#76998: Guix Home leaves user shepherd on logout, starts new instance on login
which was filed against the guix package, has been closed.
The explanation is attached below, along with your original report.
If you require more details, please reply to 67863 <at> debbugs.gnu.org.
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76998: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=76998
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Contact help-debbugs <at> gnu.org with problems
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Hello :)
Ludovic Courtès <ludo <at> gnu.org> writes:
>> In any case, what shepherd 1.0.4 does is stop the bleeding, but not fix the problem:
>> It prevents two (or 100) user shepherds for the same user from running in parallel.
>> It does not stop shepherd when a user closed all their sessions.
>
> Yes. It just occurred to me that we probably just got it wrong from the
> start: ‘XDG_RUNTIME_DIR’ (/run/user/$UID) is specified as having limited
> lifetime. Quoth
> <https://specifications.freedesktop.org/basedir-spec/latest/>:
>
> The lifetime of the directory MUST be bound to the user being logged
> in. It MUST be created when the user first logs in and if the user
> fully logs out the directory MUST be removed.
>
> So it was probably a bad idea in the first place for shepherd to store
> its socket in /run/user/$UID (even more so that this directory doesn’t
> exist on systems without elogind/systemd). GnuPG avoids
> $XDG_RUNTIME_DIR for exactly this reason (there’s a comment in
> ‘homedir.c’).
Minor correction here. Looking at the source code, GnuPG avoids the
XDG_RUNTIME_DIR environment variable, but it still tries to use the
/run/user/$UID directory, if it exists.
> So, what can we do?
>
> In the Shepherd 1.1, we could default to $XDG_STATE_HOME instead; we
> probably shouldn’t change that in 1.0.x.
Not sure here, the specification says the following about this location:
> The $XDG_STATE_HOME contains state data that *should persist between
> (application) restarts*, but that is not important or portable enough
> to the user that it should be stored in $XDG_DATA_HOME.
So... control socket does not seem to fit that description.
> Any other idea?
Well, since you have mentioned the GnuPG as an example, we could just
mirror what it does, and what I have suggested before.
--8<---------------cut here---------------start------------->8---
$ mkdir /tmp/xxx && cd /tmp/xxx
$ guix shell -u test -C findutils gnupg coreutils bash procps -- env HOME=/tmp/xxx GNUPGHOME=/tmp/xxx bash
test <at> xx ~ [env]$ gpg-agent --daemon
gpg-agent[2]: directory '/tmp/xxx/private-keys-v1.d' created
gpg-agent[3]: gpg-agent (GnuPG) 2.4.7 started
test <at> xx ~ [env]$ find /run/user
/run/user
/run/user/1000
/run/user/1000/gnupg
/run/user/1000/gnupg/d.j1yiifhhjrep9xunazyff54c
/run/user/1000/gnupg/d.j1yiifhhjrep9xunazyff54c/S.gpg-agent.ssh
/run/user/1000/gnupg/d.j1yiifhhjrep9xunazyff54c/S.gpg-agent.browser
/run/user/1000/gnupg/d.j1yiifhhjrep9xunazyff54c/S.gpg-agent.extra
/run/user/1000/gnupg/d.j1yiifhhjrep9xunazyff54c/S.gpg-agent
test <at> xx ~ [env]$ ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
test 1 0.0 0.0 5136 4068 ? S 13:32 0:00 bash
test 3 0.0 0.0 5516 2400 ? Ss 13:32 0:00 gpg-agent --daemon
test 5 0.0 0.0 5224 3852 ? R+ 13:32 0:00 ps aux
test <at> xx ~ [env]$ rm -r /run/user/1000/gnupg
gpg-agent[3]: socket file has been removed - shutting down
gpg-agent[3]: gpg-agent (GnuPG) 2.4.7 stopped
test <at> xx ~ [env]$ find /run/user
/run/user
/run/user/1000
test <at> xx ~ [env]$ ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
test 1 0.0 0.0 5136 4068 ? S 13:32 0:00 bash
test 8 0.0 0.0 5224 3776 ? R+ 13:33 0:00 ps aux
--8<---------------cut here---------------end--------------->8---
So my suggestion is that when the socket is deleted, the shepherd
process stops itself.
Tomas
--
There are only two hard things in Computer Science:
cache invalidation, naming things and off-by-one errors.
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I am trying to use the awesome Guix Home Shepherd service for syncthing (home-syncthing-service-type).
Syncthing works fine but every time I log out of my last user session and log back in again, a new instance of the user shepherd is started (and tries to start syncthing again).
After logging out and in a few times, there are multiple user shepherd processes.
Suspected cause: Apparently the user shepherd process is not killed on last logout before elogind (correctly) removes XDG_RUNTIME_DIR.
So on next login, a new empty XDG_RUNTIME_DIR is created, causing a new user shepherd to be started while the old one is still running happily.
This seems to be a general issue and not particular to the syncthing home service.
System: Guix System on x86_64
Guix commit: ac61e9705fb8c450c6cd0c1731fbb1b909c1f944
--
Uli
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