The most primitive values are Integer or String. Which work as expected.
Array values can only have Strings inside.
The empty object {} means that it doesn't have a default value, but can be overriden by absolutely any JSON.
After defining your defaults, you can override them using another json file on your current environment. For example, if you are on your development machine, create config/development.json and add there only the values you want to change (always remember to .gitignore this file!):
Excellent! Now you only need to configure your production server.
You have two options; first, do the same as development, but create the file config/production.json on your server, and make sure the NODE_ENV environment variable is set to production.
The other and recommended option for production, is to use environment variables. Here's an example of all the variables you should set to override the previous example:
All the keys are transformed from camelCase to CONSTANT_CASE.
Nested values, just add a _, for example from auth.user as AUTH_USER.
Arrays should be divided by commas ,
And JSON values are a JSON string.
DOS Config Options
You can only configure the default location of your config folder setting the environment variable CONFIG_PATH, e.g: CONFIG_PATH=/usr/src/config. On that folder it will look for the defaults.json and optionally for the {NODE_ENV}.json.