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scalaakka

Akka Cluster Connection Refused Between Machines

I am attempting to make a project using Akka Clustering, and have been using the akka-cluster-sample-scala from Lightbend(https://github.com/akka/akka-samples/tree/2.6/akka-sample-cluster-scala) as a base. As it lacks much direct information on connecting across a network, I modified the application.conf to look more like this:

akka {
  actor {
    provider = cluster

    serialization-bindings {
      "sample.cluster.CborSerializable" = jackson-cbor
    }
  }
  remote {
    artery {
      canonical.hostname = "127.0.0.1"
      canonical.port = 0
    }
  }
  cluster {
    seed-nodes = [
      "akka://ClusterSystem@131.194.71.132:25251",
      "akka://ClusterSystem@131.194.71.132:25252",
      "akka://ClusterSystem@131.194.71.133:25251",
      "akka://ClusterSystem@131.194.71.133:25252"]
    downing-provider-class = "akka.cluster.sbr.SplitBrainResolverProvider"
  }
}

When run across these two machines, Akka fails to be able to connect over TCP between them, leading to the following warnings:

[info] [2020-09-28 14:34:37,877] [WARN] [akka.stream.Materializer] [] [ClusterSystem-akka.actor.default-dispatcher-5] - [outbound connection to [akka://ClusterSystem@131.194.71.132:25251], control stream] Upstream failed, cause: StreamTcpException: Tcp command [Connect(131.194.71.132:25251,None,List(),Some(5000 milliseconds),true)] failed because of java.net.ConnectException: Connection refused

Is there anything notably wrong that may be causing this, or something more specifically needing to be reconfigured in order to allow connection over TCP between these machines?

Solution

  • My question was answered by JohanAndren on the Discuss Lightbend forums:

    https://discuss.lightbend.com/t/akka-cluster-connection-refused-between-machines/7263

    The answer was that you cannot use the 127.0.0.1 localhost definition, all nodes must use their public ips/hostnames and ports.