Add link to working example of BuildEnvPlugin

[ryanberckmans]

It took me awhile to figure out how to run the scalac optimizer for only a production build. I used the BuildEnvPlugin described here and thought readers might benefit from the docs linking to a working example.

[lightbend-cla-validator]

Hi @ryanberckmans,

Thank you for your contribution! We really value the time you've taken to put this together.

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[ryanberckmans]

I signed the Lightbend Contributors License Agreement.

[nigredo-tori]

Maybe we should simplify the code itself, so that everything happens in build.sbt? Like

ThisBuild / buildEnv := ...
ThisBuild / onLoadMessage := ...

lazy val app = project
  .in(file("."))
  .enablePlugins(JavaAppPackaging)
  .settings(
    // common
    name := "my-app",
    libraryDependencies += "com.typesafe" % "config" % "1.3.0",
    // environment-specific
    mappings in Universal += {
      val confFile = buildEnv.value match {
	case BuildEnv.Developement => "dev.conf"
	case BuildEnv.Test => "test.conf"
	case BuildEnv.Stage => "stage.conf"
	case BuildEnv.Production => "prod.conf"
      }
      ((resourceDirectory in Compile).value / confFile) -> "conf/application.conf"
    }
  )

AutoPlugin feels too heavy for a simple example.

[ryanberckmans]

That sounds good to me. I wasn't sure how to get it working with only code in build.sbt.

[muuki88]

Thanks a lot for sharing your work 😊

I'm totally fine with merging this. There is an existing collection of examples here: https://github.com/muuki88/sbt-native-packager-examples

You could also add it there

[ryanberckmans]

@muuki88 good idea! muuki88/sbt-native-packager-examples#16

Can we also merge it here? It's nice to have a reference to a working example at the site of the pertinent docs.

[muuki88]

Done :)