Condenser can also be configured using environment variables instead of copying defaults.json. They are defined in the file named custom-environment-variables.json. Another super easy way to run condenser is to use the official docker image and just set the necessary environment variables upon run, ex.:

docker run -d --env SDC_DATABASE_URL=mysql://user:pass:@localhost/steemit_dev -p 8080:8080 steemit/condenser

Thanks for helping out, Tim!