Akka AssociationError - LAN address vs localhost - scala

Question

I am new to akka and am trying to get a sample to work between multiple JVMs. I am working from the example shown here but am encountering a problem. At the end of the log below, you can see that there in an AssociationError, saying connection to 127.0.0.1:2552 was refused.
Earlier in the log (15:35:24.543), I see that remoting was started, and is listening on my LAN address (which I have shown as WWW.XXX.YYY.ZZZ), rather than on localhost.
15:35:24.307 [RandomOrgSystem-akka.actor.default-dispatcher-2] INFO akka.event.slf4j.Slf4jLogger - Slf4jLogger started
15:35:24.319 [RandomOrgSystem-akka.actor.default-dispatcher-2] DEBUG akka.event.EventStream - logger log1-Slf4jLogger started
15:35:24.320 [RandomOrgSystem-akka.actor.default-dispatcher-2] DEBUG a.a.LocalActorRefProvider$SystemGuardian - now supervising Actor[akka://RandomOrgSystem/system/UnhandledMessageForwarder#883086044]
15:35:24.320 [RandomOrgSystem-akka.actor.default-dispatcher-2] DEBUG akka.event.EventStream - Default Loggers started
15:35:24.320 [RandomOrgSystem-akka.actor.default-dispatcher-2] DEBUG a.e.LoggingBus$$anonfun$startDefaultLoggers$2$$anon$1 - started (akka.event.LoggingBus$$anonfun$startDefaultLoggers$2$$anon$1#45de530a)
15:35:24.325 [RandomOrgSystem-akka.actor.default-dispatcher-4] DEBUG a.a.LocalActorRefProvider$SystemGuardian - now supervising Actor[akka://RandomOrgSystem/system/remoting-terminator#-1650950485]
15:35:24.339 [RandomOrgSystem-akka.actor.default-dispatcher-3] DEBUG a.r.RemoteActorRefProvider$RemotingTerminator - started (akka.remote.RemoteActorRefProvider$RemotingTerminator#4f27077b)
15:35:24.355 [RandomOrgSystem-akka.actor.default-dispatcher-2] DEBUG a.a.LocalActorRefProvider$SystemGuardian - now supervising Actor[akka://RandomOrgSystem/system/transports#300935452]
15:35:24.356 [RandomOrgSystem-akka.actor.default-dispatcher-3] DEBUG a.r.Remoting$TransportSupervisor - started (akka.remote.Remoting$TransportSupervisor#2cf5006)
15:35:24.359 [RandomOrgSystem-akka.actor.default-dispatcher-3] INFO Remoting - Starting remoting
15:35:24.364 [RandomOrgSystem-akka.actor.default-dispatcher-2] DEBUG a.a.LocalActorRefProvider$SystemGuardian - now supervising Actor[akka://RandomOrgSystem/system/endpointManager#-594071077]
15:35:24.364 [RandomOrgSystem-akka.actor.default-dispatcher-2] DEBUG a.r.RemoteActorRefProvider$RemotingTerminator - now monitoring Actor[akka://RandomOrgSystem/system]
15:35:24.373 [RandomOrgSystem-akka.actor.default-dispatcher-2] DEBUG akka.remote.EndpointManager - started (akka.remote.EndpointManager#7ad99f4a)
15:35:24.534 [RandomOrgSystem-akka.actor.default-dispatcher-3] DEBUG a.r.Remoting$TransportSupervisor - now supervising Actor[akka://RandomOrgSystem/system/transports/akkaprotocolmanager.tcp0#-2000194523]
15:35:24.537 [RandomOrgSystem-akka.actor.default-dispatcher-3] DEBUG a.r.transport.AkkaProtocolManager - started (akka.remote.transport.AkkaProtocolManager#749cd006)
15:35:24.543 [RandomOrgSystem-akka.actor.default-dispatcher-5] INFO Remoting - Remoting started; listening on addresses :[akka.tcp://RandomOrgSystem#WWW.XXX.YYY.ZZZ:2552]
15:35:24.545 [RandomOrgSystem-akka.actor.default-dispatcher-2] INFO Remoting - Remoting now listens on addresses: [akka.tcp://RandomOrgSystem#WWW.XXX.YYY.ZZZ:2552]
15:35:24.548 [RandomOrgSystem-akka.actor.default-dispatcher-2] DEBUG a.a.LocalActorRefProvider$SystemGuardian - now supervising Actor[akka://RandomOrgSystem/system/remote-watcher#-245042739]
15:35:24.549 [RandomOrgSystem-akka.actor.default-dispatcher-2] DEBUG a.a.LocalActorRefProvider$SystemGuardian - now supervising Actor[akka://RandomOrgSystem/system/remote-deployment-watcher#1846115901]
15:35:24.550 [RandomOrgSystem-akka.actor.default-dispatcher-3] DEBUG akka.remote.RemoteDeploymentWatcher - started (akka.remote.RemoteDeploymentWatcher#730a4a32)
15:35:24.550 [RandomOrgSystem-akka.actor.default-dispatcher-4] DEBUG a.a.LocalActorRefProvider$SystemGuardian - now supervising Actor[akka://RandomOrgSystem/system/deadLetterListener#1544852868]
15:35:24.552 [RandomOrgSystem-akka.actor.default-dispatcher-4] DEBUG akka.event.DeadLetterListener - started (akka.event.DeadLetterListener#79a422d9)
15:35:24.555 [RandomOrgSystem-akka.actor.default-dispatcher-5] DEBUG akka.remote.RemoteWatcher - started (akka.remote.RemoteWatcher#4aa0560e)
15:35:24.555 [RandomOrgSystem-akka.actor.default-dispatcher-5] INFO akka.actor.ActorSystemImpl - Started
15:35:24.559 [RandomOrgSystem-akka.actor.default-dispatcher-5] DEBUG a.a.LocalActorRefProvider$Guardian - now supervising Actor[akka://RandomOrgSystem/user/buffer#-400157724]
15:35:24.570 [RandomOrgSystem-akka.actor.default-dispatcher-5] DEBUG RemoteActorRefProvider - [akka://RandomOrgSystem/] Instantiating Remote Actor [akka.tcp://RandomOrgSystem#127.0.0.1:2552/remote/akka.tcp/RandomOrgSystem#WWW.XXX.YYY.ZZZ:2552/user/buffer/client]
15:35:24.581 [RandomOrgSystem-akka.actor.default-dispatcher-3] DEBUG akka.remote.RemoteWatcher - Watching: [akka://RandomOrgSystem/system/remote-deployment-watcher -> akka.tcp://RandomOrgSystem#127.0.0.1:2552/remote/akka.tcp/RandomOrgSystem#WWW.XXX.YYY.ZZZ:2552/user/buffer/client]
15:35:24.582 [RandomOrgSystem-akka.actor.default-dispatcher-3] DEBUG c.b.n.akka.demo.RandomOrgBuffer - started (com.blogspot.nurkiewicz.akka.demo.RandomOrgBuffer#3012db7c)
15:35:24.584 [RandomOrgSystem-akka.actor.default-dispatcher-3] DEBUG akka.remote.EndpointManager - now supervising Actor[akka://RandomOrgSystem/system/endpointManager/reliableEndpointWriter-akka.tcp%3A%2F%2FRandomOrgSystem%40127.0.0.1%3A2552-0#-126941538]
15:35:24.594 [RandomOrgSystem-akka.actor.default-dispatcher-5] DEBUG a.remote.ReliableDeliverySupervisor - started (akka.remote.ReliableDeliverySupervisor#b8235a1)
15:35:24.594 [RandomOrgSystem-akka.actor.default-dispatcher-5] DEBUG a.remote.ReliableDeliverySupervisor - now monitoring Actor[akka://RandomOrgSystem/system/endpointManager#-594071077]
15:35:24.594 [RandomOrgSystem-akka.actor.default-dispatcher-5] DEBUG a.remote.ReliableDeliverySupervisor - now supervising Actor[akka://RandomOrgSystem/system/endpointManager/reliableEndpointWriter-akka.tcp%3A%2F%2FRandomOrgSystem%40127.0.0.1%3A2552-0/endpointWriter#118183353]
15:35:24.606 [RandomOrgSystem-akka.actor.default-dispatcher-5] DEBUG akka.remote.EndpointWriter - started (akka.remote.EndpointWriter#4b069693)
15:35:24.606 [RandomOrgSystem-akka.actor.default-dispatcher-5] DEBUG akka.remote.EndpointWriter - now monitoring Actor[akka://RandomOrgSystem/system/endpointManager/reliableEndpointWriter-akka.tcp%3A%2F%2FRandomOrgSystem%40127.0.0.1%3A2552-0#-126941538]
15:35:24.616 [RandomOrgSystem-akka.actor.default-dispatcher-3] DEBUG a.r.transport.AkkaProtocolManager - now supervising Actor[akka://RandomOrgSystem/system/transports/akkaprotocolmanager.tcp0/akkaProtocol-tcp%3A%2F%2FRandomOrgSystem%40127.0.0.1%3A2552-1#-1464884820]
15:35:24.631 [RandomOrgSystem-akka.actor.default-dispatcher-4] DEBUG a.r.transport.ProtocolStateActor - started (akka.remote.transport.ProtocolStateActor#620b5b80)
15:35:24.656 [RandomOrgSystem-akka.actor.default-dispatcher-5] ERROR akka.remote.EndpointWriter - AssociationError [akka.tcp://RandomOrgSystem#WWW.XXX.YYY.ZZZ:2552] -> [akka.tcp://RandomOrgSystem#127.0.0.1:2552]: Error [Association failed with [akka.tcp://RandomOrgSystem#127.0.0.1:2552]] [
akka.remote.EndpointAssociationException: Association failed with [akka.tcp://RandomOrgSystem#127.0.0.1:2552]
Caused by: akka.remote.transport.netty.NettyTransport$$anonfun$associate$1$$anon$2: Connection refused: /127.0.0.1:2552
]
I'd like it if the remoting started on the localhost address so that I don't have to reconfigure when I change IP address. My application.conf contains:
akka {
log-config-on-start = off
loggers = ["akka.event.slf4j.Slf4jLogger"]
loglevel = "DEBUG"
actor {
provider = "akka.remote.RemoteActorRefProvider"
debug {
receive = on
autoreceive = on
lifecycle = on
unhandled = on
}
deployment {
/buffer/client {
remote = "akka.tcp://RandomOrgSystem#127.0.0.1:2552"
}
}
}
remote {
transport = "akka.remote.netty.NettyRemoteTransport"
log-sent-messages = on
netty {
hostname = "127.0.0.1"
}
}
}
Thanks,
Tom

Answer 1

Try changing your remote section to:
remote {
transport = "akka.remote.netty.NettyRemoteTransport"
log-sent-messages = on
netty.tcp {
hostname = "127.0.0.1"
}
}
Because the config is wrong and you are not specifying the hostname property, it defaults to using the host ip. Setting up the config as above will allow you to use the loopback instead.