play-scala-sbt-assembly-example

This is a working example of how to deploy Play app using sbt-assembly instead of using sbt-native-packager. It is based on playframework/play-scala-starter-example and Play docs

Also, it attempts to answer Stack Overflow question Merge Strategy in sbt assembly and missing application loader

Deploying:

1. Add sbt-assembly to project/plugins.sbt:

   addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.5")
   

2. Exclude docs from package:

   sources in (Compile, doc) := Seq.empty
   publishArtifact in (Compile, packageDoc) := false
   

3. Define assemblyMergeStrategy

   assemblyMergeStrategy in assembly := {
     case manifest if manifest.contains("MANIFEST.MF") =>
       // We don't need manifest files since sbt-assembly will create
       // one with the given settings
       MergeStrategy.discard
     case referenceOverrides if referenceOverrides.contains("reference-overrides.conf") =>
       // Keep the content for all reference-overrides.conf files
       MergeStrategy.concat
     case x =>
       // For all the other files, use the default sbt-assembly merge strategy
       val oldStrategy = (assemblyMergeStrategy in assembly).value
       oldStrategy(x)
   }
   

4. Package with sbt assembly which should create a package in:

   /Users/mario/IdeaProjects/play-scala-sbt-assembly-example/target/scala-2.12/play-scala-sbt-assembly-example-assembly-1.0-SNAPSHOT.jar
   

5. Run with

   java -Dplay.http.secret.key=ad31779d4ee49d5ad5162bf1429c32e2e9933f3 -jar /Users/mario/IdeaProjects/play-scala-sbt-assembly-example/target/scala-2.12/play-scala-sbt-assembly-example-assembly-1.0-SNAPSHOT.jar
   

6. Test by hitting localhost:9000/