Enable option "prometheus_start_timeout" to configure the prometheus.service.

[gmej]

Enabling this option for the service file is needed so we can tell the service how much to wait before failing the service initialization. I find this useful in my setup, as Prometheus starts on boot but it needs of a NFS mount, and Prometheus startup fails, instead of waiting for that condition to be true.

Also I find this should be something not too complicated, as the option "prometheus_start_timeout" is already present and working.

[gmej]

In my case, I added these options to the Prometheus.service file:

TimeoutStartSec=600s
RestartSec=5

I realized I needed both options, as only TimeoutStartSec did not solve my problem. Maybe the solution could be completely parse all the options in the service file to variables in the main.yaml file?