Daemons started by systemd shouldn't fork into the background if
possible, because if multiple forked processes exist, systemd has
a hard time determining the main process ID.
In a memory constrained environment, the OOM killer may cause
ejabberd to exit without any trace. Because epmd keeps running,
systemd wouldn't notice the error condition, and as a result it
won't restart the server.
With ejabberd running in foreground, systemd is able to obtain the
correct exit code (137 in this case, instead of 0) and schedules a
restart. The administrator can then see what happend by looking at
systemctl status ejabberd.
With "ProtectSystem", /usr is mounted read-only, so things will fail
when e.g. /usr/local is used as the installation prefix. Whether such
options make sense depends on the environment, so they should rather be
set by package maintainers and/or admins.
Make sure the "ExecStop" command line blocks until ejabberd is actually
stopped. This prevents systemd from killing the ejabberd process(es)
immediately.
Also, let the "ExecStart" command line block until ejabberd's startup is
completed. This makes sure that services which depend on ejabberd
aren't started up too early.
The "reload_config" command doesn't work the way admins would typically
expect, so it shouldn't be exposed via systemd. Those who understand
the behavior can execute the command using ejabberdctl.
Admins might expect ejabberd to be able to access data below /home or
/tmp. For example, they might use those locations to dump/restore
Mnesia backups, or as a document root for mod_http_fileserver or
mod_http_upload.
Fixes#1297.
