There are three ways to control an emulator:

1. Regular adb commands
2. Using a console port
3. Using a gRPC port

At boot time each emulator allocates 2 ports on the host’s loopback interface: a console port and a gRPC bridge port. The console port can be established using the serial number of emulator, for example emulator-5554’s console port is 5554, emulator-5556 - 5556. If you want to make sure emulator uses a particular console port you can start the emulator with a parameter:

$ emulator @Nexus_5X_API_23 -port <port>

gRPC bridge port is usually calculated as console port + 3000, so for emulator-5554 default gRPC port will be 8554. If you want to make sure emulator uses a particular grpc bridge port you can start the emulator with a parameter:

$ emulator @Nexus_5X_API_23 -grpc <port>

Run emulator console command

This request will execute an emulator console command:

val devices: List<Device> = adb.execute(
    request =
    EmulatorCommandRequest(
        "help",
        InetSocketAddress("localhost", 5556)
    )
)

This request is completely different to other requests: it connects directly to emulator instead of adb server. For simplicity, it can be used in the same way as adb server requests and shares the socket creation logic with other requests.

Run gRPC bridge commands

Adam bundles a gRPC client for emulator gRPC bridge. The spec is generated from emulator_controller.proto

Please refer to the gRPC docs on using the client. A very simple example looks something like this:

val channel = ManagedChannelBuilder.forAddress(grpcHost, grpcPort).apply {
    usePlaintext()
    executor(Dispatchers.IO.asExecutor())
}.build()
val client = EmulatorControllerGrpcKt.EmulatorControllerCoroutineStub(channel)
val state = client.getVmState(Empty.getDefaultInstance())

Please refer to the emulator_controller.proto for the supported functionality.