Systemd - Overriding specific unit sections

This error most likely occurs during startups and is usually caused by errors or missing parameters in the service unit configuration. In my case, the service provided by a vendor, let's call it 'fancy.service', was misconfigured out of the box which led to these errors in the system's journal:

 [root@server ~]# journalctl

 ...  
 Jun 21 20:02:54 server.example.com systemd[992]: fancy.service: Failed to determine user credentials: No such process  
 Jun 21 20:02:54 server.example.com systemd[992]: fancy.service: Failed at step USER spawning /usr/bin/sh: No such process  
 ...

The root cause was the order in which the services were started. This 'fancy.service' didn't have any 'Wants=' or 'After=' declared although it required having network (network.target) access and being able to authenticate users (sssd.service), so let's fix that. First, create the overrides-directory for the service and add the required settings to a '.conf'-file:

 [root@server ~]# mkdir /etc/systemd/system/fancy.service.d  
 [root@server ~]# cat << EOF >> /etc/systemd/system/fancy.service.d/overrides-unit.conf  
 [Unit]  
 After=network.target sssd.service  
 Wants=sssd.service  
 EOF

Now to test the changes, reboot the server:

 [root@server ~]# systemctl reboot

After the reboot, the service started as expected in my case.

Feel free to comment and / or suggest a topic.

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