This is a script for pre-starting (systemd or otherwise) multiple instances of Factorio servers on Linux.
Make sure to edit the user/group in the service file.
factorio-servers goes in /etc/defaults/
factorio@.service goes in /lib/systemd/system/factorio@.service
pre-start-factorio goes in /usr/local/bin/
config.ini-template goes in $FACTORIO_PATH/servers/
Once this is in place, you need to do a systemctl daemon-reload.
In $FACTORIO_PATH/saves/, there has to be a mapping.csv file which will map your maps names to a port.
The mapping is as follow: \<port>,\<mapname.zip>
There is also a template for the configs to use with the servers (that goes in $FACTORIO_PATH/servers/) that is the template for the settings of all thes servers.
You need to dump your save files in $FACTORIO_PATH/saves/ along with the mapping.csv file.
Basically it just copies files around and makes sure that nothing overwrites other servers file. The initial setup links the mods to the (new) server. You can then add a mod to each servers. This way if you want "basic" mods to be installed on all servers, they will be.
Do not remove/modify the lines in the config.ini-template where it says {PORT}, those are used by the pre-startup-script to generate a config file on the fly for each server.
The config.ini for each server ends up in /tmp/factorio-config.$PORT
This config is removed every time the server restarts. I'll probably move it around instead and keep it with the server so that if you change the settings for a single server, it's permanent.
Make changes to make each server config.ini permanent.