Config files in DeployHQ are files that you want to upload during a deployment, but not keep in your repository. This is particularly useful for configuration files that might contain sensitive data such as a database config file.
To add a config file, head to your project's Settings dropdown, then the Config Files option. Click to add a new config file, entering the full path to it as the name, then any data you need it to contain.
If you wish to deploy the file to certain environments, uncheck the Upload this file to all current and future servers? option and you'll be able to choose specific servers that have been configured in your project. As a result, you can set up multiple configuration files for each environment type (development, staging, production etc) and only deploy them where you need to.