I think you may want something like this (note the manifestSettings
added to the settings of the project).
import sbt._
import Keys._
import java.util.Date
import sbt.Package.ManifestAttributes
object MyBuild extends Build {
lazy val manifestSettings = Seq(
packageOptions in (Compile, packageBin) +=
Package.ManifestAttributes( "Build" -> "true" )
)
lazy val root = Project(id = "root", base = file(".")).settings(manifestSettings: _*)
}
Then you should be able to call package
and have the a jar with the extra manifest entry.
Edit
To get the ("Buid" -> <current time>)
the manifestSettings
should be
lazy val manifestSettings = Seq(
packageOptions in (Compile, packageBin) +=
Package.ManifestAttributes( "Build" -> new Date().toString() )
)