[Mimedefang] REVISED: postfix/mimedefang socket

[Bill Cole]

On 24 Sep 2017, at 17:13, Michael Fox wrote:

>> Dianne will likely give a definitive authoritative answer but having
>> adapted the MD startup script to multiple system control 
>> environments, I
>> don't see anything especially risky. The only potential issue I can
>> think of is if you're trying to shut down or reboot in a pathological
>> circumstance where the mimedefang.pl worker perl sub-processes refuse 
>> to
>> exit and the supervisory process (e.g. init) has no last resort
>> mechanism to arbitrarily slaughter hung children. There's nothing 
>> quite
>> so annoying as a "hung going down" system.
>
> Thanks Bill,
>
> That makes sense.
>
> One option would be for the MIMEDefang team to provide the necessary 
> systemd control files (whatever they're called).

They are called "unit files" but including one in the base code would 
not help.

> That way, they could define restart any way they like, such as "stop 
> wait" followed by "start".

Nope. A service definition in a unit file has an ExecStart definition 
and maybe an ExecStop definition, but there is no support in systemd for 
an ExecRestart attribute. It's a design flaw in systemd, which ALWAYS 
implements "systemctl restart" as a stop then a start.

> I know systemd is hated by many.

Don't get me started...

> But it is what Ubuntu 16.04 LTS uses.

So it's the Ubuntu/Debian package maintainer's job to create a suitable 
unit file just as they've created their own init script.