Question

Section 3.4 of Grails documentation says that Grails app can be configured from an external source:

grails.config.locations = [
    "classpath:${appName}-config.properties",
    "classpath:${appName}-config.groovy",
    "file:${userHome}/.grails/${appName}-config.properties",
    "file:${userHome}/.grails/${appName}-config.groovy" ]

Also, it is possible to load config by specifying a class that is a config script:

grails.config.locations = [com.my.app.MyConfig]

My questions are:

1. Could you please give an example of how MyConfig class implementation could look like? It is not quite clear from the documentation.
2. If I want to use some external JSON REST service as a source for my config data, how can this be implemented?

Answer 1

Answer for second question: you can do that in BootStrap.groovy init closure, because basically, it allows you to execute any code:

// Inject grails app
def grailsApplication

def init = { servletContext ->
    def externalValue = getItUsingRest(someUrl)
    grailsApplication.config.my.custom.var = externalValue
}

Depending on version of grails you are using, you might need to use

org.codehaus.groovy.grails.commons.ConfigurationHolde.config

to get to config instead.