sbt-protoc

This plugin uses protoc to generate code from proto files. This SBT plugin is meant to supersede sbt-protobuf and sbt-scalapb.

Highlights

1. Uses protoc-jar by default (no need to install protoc)
2. Generates source code directly under src_managed by default (works better with IntelliJ)
3. Supports compiling protos in both test and compile configuration.
4. Supports JVM-based code generators. Write your own custom code generator.
5. Straightforward: No PB.protobufSettings, packaged as auto-plugin.

Installation

Step 1: create project/protoc.sbt with:

addSbtPlugin("com.thesamet" % "sbt-protoc" % "0.99.25")

libraryDependencies += "com.thesamet.scalapb" %% "compilerplugin" % "0.9.0"

Step 2: add to build.sbt:

If you only want to generate Java:

PB.targets in Compile := Seq(
  PB.gens.java -> (sourceManaged in Compile).value
)

A version of protobuf-java is going to get added to the runtime dependencies. To explicitly set this version you can write:

PB.targets in Compile := Seq(
  PB.gens.java("3.7.0") -> (sourceManaged in Compile).value
)

For ScalaPB:

PB.targets in Compile := Seq(
  scalapb.gen() -> (sourceManaged in Compile).value
)

To generate Java + Scala with Java conversions:

PB.targets in Compile := Seq(
  PB.gens.java -> (sourceManaged in Compile).value,
  scalapb.gen(javaConversions = true) -> (sourceManaged in Compile).value
)

To download an artifact and use it as a code generator plugin:

libraryDependencies += "io.grpc" % "protoc-gen-grpc-java" % "1.23.0" asProtocPlugin()

PB.targets in Compile := Seq(
  PB.gens.plugin("grpc-java") -> (sourceManaged in Compile).value,
)

Note the asProtocPlugin provided to the dependency, this is equivalent to:

libraryDependencies += "io.grpc" % "protoc-gen-grpc-java" % "1.23.0" % "protobuf" artifacts(
  Artifact("protoc-gen-grpc-java", PB.ProtocPlugin, "exe", "linux-x86_64"))

with the operating system replaced accordingly to the system you are running on. You can use the full syntax in case the code generator you are trying to download follows a different pattern.

Step 3: Put some protos in src/main/protobuf and compile

Additional options

The options below need to be scoped to either Compile or Test (if unsure, you probably want Compile)

Example settings:

// Additional directories to search for imports:
PB.includePaths in Compile ++= Seq(file("/some/other/path"))

// Make protos from some Jar available to import.
libraryDependencies ++= Seq(
  "com.google.protobuf" % "protobuf-java" % "3.7.0" % "protobuf"
)

// Changing where to look for protos to compile (default src/main/protobuf):
PB.protoSources in Compile := Seq(sourceDirectory.value / "somewhere")

// Additional options to pass to protoc:
PB.protocOptions in Compile := Seq("-xyz")

// Excluding some proto files:
excludeFilter in PB.generate := "test-*.proto"

// Before version 0.99.15, when compiling in Windows, Python was used to bridge
// protoc and this JVM. To set the path for Python.exe:
// Note that this must be Python2 and not Python3.
// Since version 0.99.15 this option has no effect, and will be removed in a
// future version.
PB.pythonExe := "/path/to/python.exe"

// Rarely needed: override where proto files from library dependencies are
// extracted to:
PB.externalIncludePath := file("/tmp/foo")

// By default we generate into target/src_managed. To customize:
PB.targets in Compile := Seq(
  scalapb.gen() -> file("/some/other/dir")
)

// Use a locally provided protoc:
PB.runProtoc in Compile := (args => Process("/path/to/protoc", args)!)

// Prevents the plugin from adding libraryDependencies to your project
PB.additionalDependencies := Nil

The following setting is needed, if you want to generate .proto definitions in the Test scope.

inConfig(Test)(sbtprotoc.ProtocPlugin.protobufConfigSettings)

Debugging

Show proto files extracted and where there are comming from:

sbt> set logLevel := Level.Debug
sbt> protocUnpackDependencies