Changing the Default Play Framework HTTP Port (without Using System Property) - scala

Question

There's an oft-asked question about changing the HTTP port to which a Play application will bind. James Ward's answer is generally accepted as the most complete, but it involves overriding the default by setting a http.port system property. However, is it possible to change this default without having to manually add it to the run command at development time, tweak the environment, or package an override in a runtime configuration?

Answer 1

This can be accomplished by setting the playDefaultPort key, as follows:
import PlayKeys._
playDefaultPort := 9123
Afterwards, you'll be able to run and testProd without needing to remember the desired port.
This works in both development:
$ sbt run
[info] Loading project definition from /Users/michaelahlers/Projects/MyApp/project
[info] Set current project to MyApp (in build file:/Users/michaelahlers/Projects/MyApp/)
--- (Running the application, auto-reloading is enabled) ---
[info] p.c.s.NettyServer - Listening for HTTP on /0:0:0:0:0:0:0:0:9123
(Server started, use Ctrl+D to stop and go back to the console...)
And production modes:
$ sbt testProd
[info] Loading project definition from /Users/michaelahlers/Projects/MyApp/project
[info] Set current project to MyApp (in build file:/Users/michaelahlers/Projects/MyApp/)
[info] Packaging /Users/michaelahlers/Projects/MyApp/target/scala-2.11/MyApp_2.11-1.0.0-SNAPSHOT-web-assets.jar ...
[info] Done packaging.
(Starting server. Type Ctrl+D to exit logs, the server will remain in background)
2016-04-08 13:09:45,594 [info] a.e.s.Slf4jLogger - Slf4jLogger started
2016-04-08 13:09:45,655 [info] play.api.Play - Application started (Prod)
2016-04-08 13:09:45,767 [info] p.c.s.NettyServer - Listening for HTTP on /0:0:0:0:0:0:0:0:9123