systemd related issues

[Nikolaos Milas]

On 8/2/2021 12:15 μ.μ., Nikolaos Milas wrote:

> How can we configure systemd to start postfix AFTER clamd at amavisd 
> (triggered by amavisd) has started?
> ...
> ...how could we configure systemd so that clamd at amavisd is also 
> stopped when amavisd is requested to stop?

Trying to answer my own question, I found:

https://serverfault.com/questions/482730/systemd-dependencies-and-boot-order

which I think provides all needed information on how to do it.

In this case, postfix.service file (/etc/systemd/postfix.service as a 
copy of /usr/lib/systemd/system/postfix.service) should include:

    Requires=amavisd.service

to make postfix start after amavisd.

Similarly, clamd at .service (/etc/systemd/clamd at .service as a copy of 
/usr/lib/systemd/system/clamd at .service) could inlcude:

    BindsTo=amavisd.service

to force clamd at amavisd to stop when amavisd is stopped.

Finally, as my systemd know-how is insufficient, could someone please 
clarify things on the need to have clamd at amavisd service enabled or not?

Specifically, is it sufficient (for correct startup and operation of 
clamd at amavisd service) that amavisd.service includes:

    Wants=clamd at amavisd.service

(already configured by default in the respective CentOS package) even if 
the service is not explicitly configured as enabled or we explicitly 
ALSO NEED to have it enabled:

    systemctl enable clamd at amavisd

and if so, why?

Thanks,
Nick