In a previous post we learned how to save the application PID in a file when we start our Grails application. We can also save the port number the application uses in a file when we run our Grails application. We must use the class EmbeddedServerPortFileWriter and add it as a listener to the GrailsApp instance. By default the server port is saved in a file application.port. But we can pass a custom file name or File object to the constructor of the EmbeddedServerPortFileWriter class.
In the following example we use the file name application.server.port to store the port number:
// File: grails-app/init/sample/Application.groovy
package sample
import grails.boot.GrailsApp
import grails.boot.config.GrailsAutoConfiguration
import groovy.transform.CompileStatic
import org.springframework.boot.actuate.system.EmbeddedServerPortFileWriter
@CompileStatic
class Application extends GrailsAutoConfiguration {
static void main(String[] args) {
final GrailsApp app = new GrailsApp(Application)
// Save port number in file name application.server.port
final EmbeddedServerPortFileWriter serverPortFileWriter =
new EmbeddedServerPortFileWriter('application.server.port')
// Add serverPortFileWriter as application listener
// so the port number is saved when we start
// our Grails application.
app.addListeners(serverPortFileWriter)
app.run(args)
}
}
When the application is started we can find the file application.server.port in the directory from where the application is started. When we open it we see the port number:
$ cat application.server.port 8080 $
Written with Grails 3.1.
