How to configure SBT to skip proguard task when some system property is given.

Question

I am using sbt, sbt-native-packager and sbt-proguard to make packages for 3 environments such as dev, staging and production environments. What I would like to do is to be able to specify whether or not to use proguard to make a package. For example, the following command make package using proguard:

$ sbt -Dforceobfuscate=true -Denv=dev rpm:pakageBin

but the following command make package without proguard

$ sbt -Denv=dev rpm:packageBin

What I tried two setting. One is overriding task by system property condition and two is overriding task with dynamic task.

1.Just overriding task by system property.

ProguardKeys.proguard in Proguard := { 
  if (sys.props.get("forceobfuscate").isDefined) {
    ( ProguardKeys.proguard in Proguard ).value
  } else {
    Seq(new File("dummy")) 
  }
}

This setting always run proguard task (I don't know why). Also I tried the following setting for just making sure overriding task can stop task.

ProguardKeys.proguard in Proguard := { 
  if (sys.props.get("forceobfuscate").isDefined) {
    // ( ProguardKeys.proguard in Proguard ).value
    Seq(new File("dummy")) 
  } else {
    Seq(new File("dummy")) 
  }
}

Indeed, above setting always skip proguard task.

2.Overriding task using dynamic task.

def obfuscateOrNot = Def.taskDyn {
  if (sys.props.get("forceobfuscate").isDefined) {
    Def.task {
      ( ProguardKeys.proguard in Proguard ).value
    }
  } else { 
    Def.task {
      Seq(new File("dummy")) 
    }
  }
}

ProguardKeys.proguard in Proguard := { 
  obfuscateOrNot.value
}

Then run the command:

$ sbt rpm:packageBin

Okay, this time skip proguard task. But when I run the command:

$ sbt -Dforceobfuscate=true rpm:packageBin

I got the following error:

sbt.Init$RuntimeUndefined: References to undefined settings at runtime.
sbt.Init$RuntimeUndefined: References to undefined settings at runtime.
setting(ScopedKey(Scope(Select(ProjectRef(file:/work/backend/,backend)),Select(ConfigKey(proguard)),Global,Global),proguard)) at RangePosition(/work/backend/build.sbt,LineRange(244,247)) referenced from ScopedKey(Scope(Select(ProjectRef(file:/work/backend/,backend)),Select(ConfigKey(proguard)),Global,Global),proguard)
    at sbt.Init$class.sbt$Init$$handleUndefined(Settings.scala:511)
    at sbt.Init$$anon$4.apply(Settings.scala:516)
    at sbt.Init$$anon$4.apply(Settings.scala:516)
    at sbt.$tilde$greater$$anon$6.apply(TypeFunctions.scala:39)
    at sbt.$tilde$greater$$anon$6.apply(TypeFunctions.scala:39)
    at sbt.std.FullInstance$$anonfun$flatten$1$$anonfun$apply$3.apply(TaskMacro.scala:51)
    at sbt.std.FullInstance$$anonfun$flatten$1$$anonfun$apply$3.apply(TaskMacro.scala:51)
    at scala.Function1$$anonfun$compose$1.apply(Function1.scala:47)
    at sbt.$tilde$greater$$anonfun$$u2219$1.apply(TypeFunctions.scala:40)
    at sbt.std.Transform$$anon$4.work(System.scala:63)
    at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:228)
    at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:228)
    at sbt.ErrorHandling$.wideConvert(ErrorHandling.scala:17)
    at sbt.Execute.work(Execute.scala:237)
    at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:228)
    at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:228)
    at sbt.ConcurrentRestrictions$$anon$4$$anonfun$1.apply(ConcurrentRestrictions.scala:159)
    at sbt.CompletionService$$anon$2.call(CompletionService.scala:28)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
[error] (proguard:proguard) sbt.Init$RuntimeUndefined: References to undefined settings at runtime.
[error] setting(ScopedKey(Scope(Select(ProjectRef(file:/work/backend/,backend)),Select(ConfigKey(proguard)),Global,Global),proguard)) at RangePosition(/work/backend/build.sbt,LineRange(244,247)) referenced from ScopedKey(Scope(Select(ProjectRef(file:/work/backend/,backend)),Select(ConfigKey(proguard)),Global,Global),proguard)
[error] Total time: 1 s, completed 2017/07/29 12:09:24

I think the error says that there is no setting for proguard but I am not sure how to set setting using dynamic task.

I would like to make above commands work well. Any solution is fine.

Answer 1

I found a solution. The solution is making proguard Seq[Setting[_]] value depending on condition.

lazy val customProguardSettings = 
  if (sys.props.get("forceobfuscate").isDefined) {
    proguardSettings ++ Seq( ... )
  } else {
    Nil
  }

customProguardSettings