scala sbt assembly “no main manifest attribute”

Question

I use assembly plugin in sbt to assemble my project. But errors happen when run by \"java -jar xx.jar\" -

\"no main manifest attribute\".

I think it\'s b

Answer 1

You can use -cp instead of -jar

java -cp xx.jar com.domain.AnyClassName

Answer 2

I had this issue while testing out Lagom.

To deploy in Lagom you can just access the -impl project and run this:

./sbt "project <your-project>-impl" dist

This will generate a zip with the executable inside.

Answer 3

In your SBT build file, define the main class.

If you are using build.sbt, then that would be:

mainClass in assembly := Some("com.domain.Main")

If you are using Build.scala then you could do something like:

lazy val app = (project in file("app")).
  settings(assemblySettings: _*)
  settings(mainClass in assembly := Some("com.domain.Main"))