ScalaPB

This module allows ScalaPB to be used in Mill builds. ScalaPB is a Protocol Buffers compiler plugin that generates Scala case classes, encoders and decoders for protobuf messages.

To declare a module that uses ScalaPB you can extend the mill.contrib.scalapblib.ScalaPBModule trait when defining your module.

This creates a Scala module which compiles .proto files in the protobuf folder of the module with ScalaPB and adds the resulting .scala sources to your module’s generatedSources.

build.mill

//| mvnDeps: ["com.lihaoyi::mill-contrib-scalapblib:$MILL_VERSION"]
package build

import contrib.scalapblib._

object example extends ScalaPBModule {
  def scalaVersion = "2.12.6"
  def scalaPBVersion = "0.7.4"
}

This defines a project with the following layout:

build.mill
example/
    src/
    protobuf/
    resources/

Configuration options

Please inspect the API docs of ScalaPBModule for all available tasks.

If you’d like to configure the options that are passed to the ScalaPB compiler directly, you can override the scalaPBOptions task, for example:

build.mill

//| mvnDeps: ["com.lihaoyi::mill-contrib-scalapblib:$MILL_VERSION"]
package build

import contrib.scalapblib._

object example extends ScalaPBModule {
  def scalaVersion = "2.12.6"
  def scalaPBVersion = "0.7.4"
  override def scalaPBOptions = "flat_package,java_conversions"
}

If you’d like to pass additional arguments to the ScalaPB compiler directly, you can override the scalaPBAdditionalArgs task, for example:

build.mill

//| mvnDeps: ["com.lihaoyi::mill-contrib-scalapblib:$MILL_VERSION"]
package build

import contrib.scalapblib._

object example extends ScalaPBModule {
  def scalaVersion = "2.12.6"
  def scalaPBVersion = "0.7.4"
  override def scalaPBAdditionalArgs =
    Seq(s"--zio_out=${Task.dest.toIO.getCanonicalPath}")
}

If you rely on any .proto files from your dependencies that requires case classes to be generated, override the scalaPBSources as follows:

build.mill

//| mvnDeps: ["com.lihaoyi::mill-contrib-scalapblib:$MILL_VERSION"]
package build

import contrib.scalapblib._

object example extends ScalaPBModule {
  def scalaVersion = "2.12.6"
  def scalaPBVersion = "0.7.4"
  override def scalaPBSources = {
    defaultResolver().classpath(
      Seq(ivy"..."),
      sources = true
    ).foreach(jar => os.unzip(jar.path, Task.dest))

    super.scalaPBSources() ++ Seq(PathRef(Task.dest))
  }
}