I have two plain configuration files for two environments: production and hot standby. The config files are in git. Users only make changes to the production config file. This of course results in a stale hot standby config. I'm wanting input on various methods to keep these files in sync. They are not identical. Different hostnames/ips/ports/etc. I'm kinda stumped. One method I thought of would be to use a templating system of some sort. These can't go into cms software (puppet/cfengine). Any ideas?