Support systemd's watchdog feature and enable it by default in the unit
file, so that ejabberd is auto-restarted if the VM becomes unresponsive.
Also, set the systemd startup type to 'notify', so that startup of
followup units is delayed until ejabberd signals readiness. While at
it, also notify systemd of configuration reload and shutdown states.
Note: "NotifyAccess=all" is required as long as "ejabberdctl foreground"
runs the VM as a new child process, rather than "exec"ing it. This way,
systemd views the ejabberdctl process itself as the main service
process, and would discard notifications from other processes by
default.
erlang-sqlite3 versions got messed up, causing ejabberd build to regress
to 1.1.6 from Jan 2018 when using rebar3 which fails to build with OTP23.
Update to correctly tagged version 1.1.9, which also has matching hex.pm
package, fixes this.
This stop overriding store_type when anonymous is enabled with other
auth modules, we don't really need that since anonymous is not taking
passwords anyway, and this was disabling scram mechanisms.
This fixes issue #2803.
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.
