[2.2.1 Scala] Running a Play subproject from sbt

[Brandon Gauthier]

Hello,

I am trying to run a Play sub project from a larger sbt root project without needing to use the project switching commands. An example of the project layout can be found on GitHub and is described below:

Project Layout:

root
├───cli
│   └─── ...(Command Line Project, Has a "main(...)")...
├───common
│   └─── ...(Library Project)...
├───core
│   └─── ...(Library Project)...
├───project
│   └─── ...(sbt stuff)...
├───web
│   └─── ...(Play Project)...
└───build.sbt

root/build.sbt:

name := "root"

version := "0.0.0-SNAPSHOT"

lazy val root = project.in(file("."))
  .aggregate(common, core, cli, web)

lazy val common = project

lazy val core = project
  .dependsOn(common)

lazy val cli = project
  .dependsOn(common, core)
 
lazy val web = project
  .settings(play.Project.playScalaSettings: _*)
  .dependsOn(common, core)

Currently the cli sub-project can be run via "cli/run" however when trying to run the web project with "web/run" I get the following exception:

> web/run
java.lang.RuntimeException: */*:playRunHooks is undefined.
        at scala.sys.package$.error(package.scala:27)
[trace] Stack trace suppressed: run last web/compile:run for the full output.
[error] (web/compile:run) */*:playRunHooks is undefined.
[error] Total time: 0 s, completed May 22, 2014 5:36:36 PM

I can proved the full stack trace if needed.

I can run the web project buy using the following project switching commands:

> project web
[info] Set current project to web (in build file:file:/{{redacted to remove my username}}/Workspace/test/)
[web] $ run


--- (Running the application from SBT, auto-reloading is enabled) ---


[info] play - Listening for HTTP on /0:0:0:0:0:0:0:0:9000

The Questions:

1. Can someone explain why the web project (and Play) run correctly via project switching but not with "web/run"?
2. Is there something I can do to my build make "web/run" work or is this a limitation of Play's sbt plugin?
   
3. If this is a limitation of Play's sbt plugin what work would need to be done to change it?

--Brandon

[Dima Golubets]

Hi Brandon, 

I've met the same problem.. I wonder if you have solved it.

[Brandon Gauthier]

No I have not. At my development shop we have just taken the approach of "Play is Different" and we use the project switching commands for Play projects and {projectname}/run for everything else. It is a pain: some of our automated scripts that call sbt had to be rewritten and it confuses new team members.

I have done a bit more research and discovered this interesting behavior:

> web/run
java.lang.RuntimeException: */*:playRunHooks is undefined.
        at scala.sys.package$.error(package.scala:27)
[trace] Stack trace suppressed: run last web/compile:run for the full output.
[error] (web/compile:run) */*:playRunHooks is undefined.

[error] Total time: 0 s, completed Jun 9, 2014 5:53:25 PM
> show */*:playRunHooks
[error] No such setting/task
[error] show */*:playRunHooks
[error]                      ^

> inspect */*:playRunHooks

[info] No entry for key.

[info] Description:

[info]

[info] Delegates:

[info]  */*:playRunHooks

[info] Related:

[info]  web/*:playRunHooks

> show web/*:playRunHooks
[info] List()
[success] Total time: 0 s, completed Jun 9, 2014 5:53:44 PM

> inspect web/*:playRunHooks

[info] Task: scala.collection.Seq[play.PlayRunHook]

[info] Description:

[info]

[info] Provided by:

[info]  {file:/{{redacted to remove my username}}/Workspace/test/}web/*:playRunHooks

[info] Defined at:

[info]  {{redacted to remove my username}}/Workspace/test/web/build.sbt:11

[info] Dependencies:

[info]  web/*:playOnStarted

[info]  web/*:playOnStopped

[info] Delegates:

[info]  web/*:playRunHooks

[info]  {.}/*:playRunHooks

[info]  */*:playRunHooks

So it looks like playRunHooks may not be scoped correctly in the case of Play as a sub-project. I also could be 100% wrong, there is a lot of magic going on in the Play sbt plugin and I have not spent a lot of time studying it.

I would really like some of the Play core developers to chime in: What is going on here? Is Play as a sub-project a supported or recommended configuration? 

Once again I'm sorry I can't be of more help,

--Brandon

[Eugene Yokota]

I think this is a bug in Play 2.2. See https://github.com/playframework/playframework/issues/3731 that I reported.

Play 2.3 looks ok.

-eugene