Akka remoting on Google Cloud VM

Question

I'm new to Akka and I'm trying to run a simple remoting actor that works on localhost on a Google Cloud VM instance.

VM has both internal and external IPs. When I start an actor with IP set to external it fails to start.

But when I'm doing this

netty.tcp {
  hostname = "<internal IP>"
  port = 45000

Everything starts off fine.

Now obviously when trying to connect from another machine internal IP doesn't resolve, so I'm trying to find the actor using the following command:

context.actorSelection("akka.tcp://Main@<external IP>:45000/user/app")

And get the following error:

[ERROR] dropping message [class akka.actor.ActorSelectionMessage] for non-local recipient [Actor[akka.tcp://Main@external IP:45000/]] arriving at [akka.tcp://Main@external IP:45000] inbound addresses are [akka.tcp://Main@internal IP:45000]

The last part does make sense, but how do I make the whole thing work?

Answer 1

Found the solution.

It's based on bind-hostname config setting available in upcoming 2.4 version:

build.sbt

resolvers += "Typesafe Snapshots" at "http://repo.akka.io/snapshots/"

libraryDependencies ++= Seq(
  "com.typesafe.akka" %% "akka-actor" % "2.4-SNAPSHOT",
  "com.typesafe.akka" %% "akka-remote" % "2.4-SNAPSHOT"
)

application.conf

akka {
  actor {
    provider = "akka.remote.RemoteActorRefProvider"
  }
  remote {
    enabled-transports = ["akka.remote.netty.tcp"]
    netty.tcp {
      hostname = "external IP"
      port = 45000
      bind-hostname = "internal IP"
    }
 }
}

You can also specify bind-port if needed.