how to define several production environments in grails - grails

Question

I know you can create several custom environment for grails.
My question is i want these custom environment to be for production mode (each environment for each department with different DB and configuration).
Are there any special way to define them ? if i deploy them as is, will the war be performant or a testing war ?
Thanks

Answer 1

The correct way to address this is through the use of Externalized Configuration.
By doing so you will give each department the flexibility of configuring your application for their environment and you won't need to package your application for each department.

Answer 2

I don't have a complete solution, but I'll share what I know.
The ServletContext provides init parameters that can be set up outside of the app. The servlet container then makes them available to the app/context. The method which returns these parameters is called initParameterNames().
For example, lets say I'm running the app with Tomcat 8 and the app is called example-app. To set up some init parameters I'd create the file $CATALINA_BASE/conf/Catalina/localhost/example-app.xml
In the file, I'd save my parameters like this:
<Context>
<Parameter name="environments.production.dataSource.url" value="jdbc:h2:anotherProdDb;MVCC=TRUE;LOCK_TIMEOUT=10000;DB_CLOSE_ON_EXIT=FALSE" override="true" />
</Context>
From Grails I would be able to access this value from the ServletContext. For example, from a GSP I can read the value like this:
application.getInitParameter('environments.production.dataSource.url')
Ideally, I would merge the init parameters with the Grails config (grailsApplication.config) early in the start up process so that the init parameters override the Grails config. But I could not figure out how to it. The Grails config is accessible from GrailsAutoConfiguration (and apparently modifiable) like this:
import grails.boot.GrailsApp
import grails.boot.config.GrailsAutoConfiguration
import grails.boot.config.GrailsApplicationPostProcessor
import grails.core.GrailsApplication
class Application extends GrailsAutoConfiguration {
static void main(String[] args) {
GrailsApp.run(Application, args)
}
GrailsApplicationPostProcessor grailsApplicationPostProcessor() {
def processor = super.grailsApplicationPostProcessor()
processor.grailsApplication.config.setAt('environments.production.dataSource.url', 'testing...')
return processor
}
}
But I don't know how access the ServletContext within the grailsApplicationPostProcessor() in order to override the Grails config with init parameters.