[Citadel Development] Re: Write server PID to citadel.lock in addition to locking it.

[IGnatius T Foobar]

  
 So here's what is on my mind regarding this.  Suggestions are welcome. 
  
 `/var/run` is a good place to put the PID file, which as previously mentioned
is also the lock file.  Mounting the same database from two different instances
of `citserver` would be A Bad Thing.  (Even though I'm still freaking amazed
at how stable the database has become once we switched to the mmap-backed
environment ... I still can't make it go corrupt no matter how hard I try.)

  
 On a regular machine, or in a jail, `/var/run` is in the right place, and
does the right thing. 
  
 In a container ... `/var/run` will not be in the same persistent volume as
the database.  That means someone could accidentally start up two containers
that have different `/var/run` but the same `/usr/local/citadel/data` with
catastrophic results. 
  
 I'm tossing around a couple of ideas: 
  
 * Writing the pid file to both $ctdldir/citadel.lock
*and* /var/run/citserver.pid 
  
 * Making /var/run/citserver.pid a symbolic link to $ctdldir/citadel.lock

  
 I really don't want to make the containerized version harder to use. 
 

[Citadel Development] Re: Write server PID to citadel.lock in addition to locking it.

[IGnatius T Foobar]

  
 Whoa, what font is that ?!! 
  
 I am aware that `/var/run` is the conventional location, and may yet move
it there.  Doing so would, however, prevent multiple instances of Citadel
Server from running on the same host.  There were definitely people doing
that in the past, but I wonder if nowadays that is still a thing, with everyone
now having virtual machines and jails and containers and all sorts of other
ways to isolate multiple workloads on the same machine. 
 

[Citadel Development] Re: Write server PID to citadel.lock in addition to locking it.

[LadySerenaKitty]

PID files are usually in /var/run and are suffixed with "pid" as seen in the attached screenshot of my /var/run

Mon Sep 18 2023 10:21:10 EDT from rss <>  Subject: Write server PID to citadel.lock in addition to locking it.
This will be useful for systems like FreeBSD that need to know a PID to monitor.