Hello! Danny Milosavljevic <dan...@scratchpost.org> skribis:
> For a real user shepherd, it would be nice if when I logged in twice using > the same user account (without logging out in-between - so resulting in two > sessions of that user) it would still only have one shepherd instance for > that user account in total - and if that instance (and remaining user > processes for that matter) went away only when I logged out from *all* > sessions of that user. > > I thought I could fake that by just trying to invoke shepherd on each session > start and have it fail on the second attempt - but apparently we will happily > start an infinite number of shepherds for one user. Is that on purpose? > > The relevant place (in shepherd) is: > > (define (open-server-socket file-name) > "Open a socket at FILE-NAME, and listen for connections there." > (with-fluids ((%default-port-encoding "UTF-8")) > (let ((sock (socket PF_UNIX SOCK_STREAM 0)) > (address (make-socket-address AF_UNIX file-name))) > (false-if-exception (delete-file file-name)) ; <===== [dannym: WTF. > Would it be better to try to connect first?] > (bind sock address) > (listen sock 10) > sock))) > > Probably not good. The ‘delete-file’ was to avoid EADDRINUSE but I wonder if it’s really a good idea. > Maybe better: > > (define (server-present? file-name) > "Open a socket at FILE-NAME, and connect to the server, if any. Return #t > if that worked." > (with-fluids ((%default-port-encoding "UTF-8")) > (let ((sock (socket PF_UNIX SOCK_STREAM 0)) > (address (make-socket-address AF_UNIX file-name))) > (false-if-exception (connect sock address))))) ; probably missing a > "[catch] close". How to do that best? That’s a pretty good test. Note that (gnu services herd) and (shepherd comm) already provide an ‘open-connection’ procedure to do that. >From a shell script, you can also simply run “herd status root” and check the exit status. > I'm trying to find the right place to insert my "dbus-daemon" invocation for > providing the user bus (note: not session bus)... What’s the difference between a “user bus” and a “session bus”? In general, my understanding is that the user dbus-daemon (session bus?) is started on demand. > Should we make a system shepherd service that invokes the user shepherd > service on behalf of users? Would that be that safe? The “guix user” approach that Mathieu shown is more flexible than having to do something in the ‘operating-system’ declaration IMO. > Or should we just expect the user to put a (shepherd with fix) invocation > into their HOME startup scripts like .xinitrc ? Note that if we did that > there's some session-specific stuff in the session's environment that > shepherd will inherit. Probably not that bad if invoked early enough. Currently that’s what I do: my ~/.xinitrc runs shepherd and that’s it. HTH, Ludo’.
