how to change the scalaPB default path of protobuf files? - scala

Question

I have a build.sbt for a couple of packages in the same project.
When I do sbt compile, my protobuf files are under [packagename]/src/main/protobuf/*,
so it won't scan these files since they have that additional package name in the path.
How to change the default protobuf file path?

Answer 1

It is unclear from your question whether your sbt build is a single or multi-project build. You can tell that it is a multi-project build if you see lines like val someSubProject = project.in(file(...).
If your build.sbt is a single project build, you can add a line to customize where protos are being scanned:
Compile / PB.protoSources += file("pkgname/src/main/protobuf")
If you have a multi-project build with a project proj1, then it should already work in the way you expect:
val proj1 = project.in(file("proj1"))
.settings(
PB.targets in Compile := Seq(
scalapb.gen(javaConversions=true) -> (sourceManaged in Compile).value / "scalapb"
),
libraryDependencies ++= Seq(
"com.thesamet.scalapb" %% "scalapb-runtime" % scalapb.compiler.Version.scalapbVersion % "protobuf",
)
)
then sbt-protoc will generate sources for the protos under proj1/src/main/protobuf. The sources will get compiled as poart of the proj1 project.
You can customize the path it looks for by setting Compile / PB.protoSources within that project's setting. For example, if you want it to generate source for protos that are in another top-level directory, you can do:
val proj1 = project.in(file("proj1"))
.settings(
PB.targets in Compile := Seq(
scalapb.gen(javaConversions=true) -> (sourceManaged in Compile).value / "scalapb"
),
Compile / PB.protoSources :=
Seq((ThisBuild / baseDirectory).value / "somewhere" / "protos"),
libraryDependencies ++= Seq(
"com.thesamet.scalapb" %% "scalapb-runtime" % scalapb.compiler.Version.scalapbVersion % "protobuf",
)
)

Answer 2

I recommend using AkkaGrpcPlugin and a multi-project SBT configuration.
Put the .proto files in a separate project and make the others depend on it. This project just has a single directory <root>/grpc/src/main/protobuf containing the .proto files. When this project is compiled it will create all the stub files which can be picked up by other projects that depend on it.
Here is an outline build.sbt file:
lazy val top_level =
(project in file("."))
.aggregate(grpc, main)
lazy val grpc =
project
.in(file("grpc"))
.settings(
???
)
.enablePlugins(AkkaGrpcPlugin)
lazy val main =
project
.in(file("main"))
.settings(
???
)
.dependsOn(grpc)
And add this to plugins.sbt:
addSbtPlugin("com.lightbend.akka.grpc" % "sbt-akka-grpc" % "1.1.1")