When does grails.config.locations get processed in Grails?

Question

I am using grails 1.2.1 and would like to specify external configuration (properties) files for the war file for my application. I understand from documentation that the proper way to do this is to specify the

grails.config.locations

list in the Config.groovy file. When I do that, however, the properties that should be set are not available to the program (in, for example, DataSource.groovy). When are these properties set?

I would like to load external properties files & then perform some parameter checking on them prior to making them available to the rest of the program. I also want to use these parameter values to set up my logging and data sources.

When the above-mentioned approach didn't work, I also tried loading them manually by doing something like this:

List locations = []

def systemConfig = System.getenv(ENV_NAME)
def cmdlineConfig = System.getProperty(ENV_NAME)

if (systemConfig) {
    println "Including configuration file specified in environment: " + systemConfig;
    locations << systemConfig
}

if(cmdlineConfig) {
    println "Including configuration file specified on command line: " + cmdlineConfig;
    locations << cmdlineConfig
}

if (!systemConfig && !cmdlineConfig)
    println "WARNING: No external configuration file defined."

locations.each { String loc ->
    File f = new File(loc)
    if (!f.exists())
        println "WARNING: File ${f.absolutePath} not found"
    else {      
        try {
            def configSupport = null
            if (loc.endsWith('.properties')) {
                Properties props = new Properties();
                props.load(f.newReader());
                println "Parsed properties file: $props"
                configSupport = new ConfigSlurper().parse(props)
            }
            else
                configSupport = new ConfigSlurper().parse(f.toURI().toURL() )
            assert configSupport != null
            println "Loaded ${loc}: $configSupport"
            grails.config = grails.config.merge(configSupport)
            println "config is now: ${grails.config}"
        }
        catch( Exception ex ) {
            println "ERROR: could not parse $loc: $ex.message"
        }
    }
}

While grails.config did get set properly, that didn't get reflected to the rest of the code. Also, this is clearly wrong since I need to be able to refer to grails.somepropname rather than to grails.config.grails.somepropname

In short, I am confused about the proper way to inject some properties into my war file and do something with their values.

Thanks,

Gene