I was recently working on a grails project and found that it is possible to read the configuration/properties defined in application.yml using spring annotation in Grails 3. Its possible in Grails 3 because it uses Spring boot under the hood. Here is an example:

import org.springframework.beans.factory.annotation.Value

class ConfigController {

String timeoutValue

def index() {
render "Timeout is: ${timeoutValue}" // Prints 'Timeout is 1200'

Content of application.yml:

sessionTimeout: 1200
contextPath: /eportal

In the above method we are using  value annotation to inject the config values from application.yml file.
The old way of retreiving the value of the configuration is:

def timeoutValue = grailsApplication.config.getProperty('server.sessionTimeout')

which is an obsolete way of doing it. So its more cleaner to user the annotation which is only available in Grails 3+.

That was all!