Maven

To get started with Akka gRPC read the client or server introductions.

Configuring what to generate

The plugin can be configured to generate either Java or Scala classes, and then server and or client for the chosen language. By default both client and server in Java are generated.

Java

<plugin>
    <groupId>com.lightbend.akka.grpc</groupId>
    <artifactId>akka-grpc-maven-plugin</artifactId>
    <version>${akka.grpc.version}</version>
    <configuration>
      <language>Java</language>
      <generateClient>false</generateClient>
      <generateServer>true</generateServer>
    </configuration>
</plugin>

Scala

<plugin>
    <groupId>com.lightbend.akka.grpc</groupId>
    <artifactId>akka-grpc-maven-plugin</artifactId>
    <version>${akka.grpc.version}</version>
    <configuration>
      <language>Scala</language>
      <generateClient>false</generateClient>
      <generateServer>true</generateServer>
    </configuration>
</plugin>

Generating server “power APIs”

To additionally generate server “power APIs” that have access to request metadata, as described here, set the serverPowerApis tag as true:

pom.xml

<plugin>
    ...
    <configuration>
      ...
      <generatorSettings>
        <serverPowerApis>true</serverPowerApis>
      </generatorSettings>
    </configuration>
</plugin>

Proto source directory

By default the plugin looks for .proto-files under src/main/protobuf (and src/main/proto). This can be changed with the protoPaths setting, which is a relative path to the project basedir. The below configuration overrides the proto path to be only src/main/protobuf:

pom.xml

<plugin>
    <groupId>com.lightbend.akka.grpc</groupId>
    <artifactId>akka-grpc-maven-plugin</artifactId>
    <version>${akka.grpc.version}</version>
    <configuration>
      <protoPaths>
        <protoPath>src/main/protobuf</protoPath>
      </protoPaths>
    </configuration>
</plugin>

Loading proto files from artifacts

In gRPC it is common to make the version of the protocol you are supporting explicit by duplicating the proto definitions in your project.

When using sbt as a build system, we also support loading your proto definitions from a dependency classpath. This is not yet supported for Maven and Gradle. If you are interested in this feature it is tracked in issue #152.

JDK 8 support

If you want to use TLS-based negotiation on JDK 8, Akka gRPC requires JDK 8 update 252 or later. JVM support for ALPN has been backported to JDK 8u252 which is now widely available. Support for using the Jetty ALPN agent has been dropped in Akka HTTP 10.2.0, and therefore is not supported by Akka gRPC.

Starting your Akka gRPC server from Maven

You can start your gRPC application as usual with:

mvn compile exec:exec