How to fix all the errors and successfully run the Akka Distributed Workers Sample Project?

1
votes

I am trying to run the Akka Distributed Workers project following the guide here https://developer.lightbend.com/guides/akka-distributed-workers-scala/

On run, it fails with series of error messages. The first one that caught my attention was:

14:42:36.747 [ClusterSystem-akka.actor.default-dispatcher-4] ERROR akka.cluster.ClusterActorRefProvider - No root guardian at [akka.tcp://[email protected]:2554]
java.lang.IllegalArgumentException: Wrong protocol of [akka.tcp://[email protected]:2554/], expected [akka]

Indeed when I take a look at the configuration "akka.tcp://[email protected]:2554" is used.

But why is the sample with the wrong format? Maybe the format changed?

Anyways I changed to "akka://[email protected]:2554" then attempted to run again...

The error about wrong protocol seems to be gone, but now I got the following error:

[error] (run-main-1) java.lang.IllegalStateException: Detected possible incompatible versions on the classpath. Please note that a given Akka version MUST be the same across all modules of Akka that you are using, e.g. if you use [2.6.0] all other modules that are released together MUST be of the same version. Make sure you're using a compatible set of libraries. Possibly conflicting versions [2.6.0, 2.5.23] in libraries [akka-persistence:2.6.0, akka-persistence-query:2.5.23, akka-coordination:2.6.0, akka-actor:2.6.0, akka-slf4j:2.6.0, akka-remote:2.6.0, akka-cluster:2.6.0, akka-protobuf-v3:2.6.0, akka-stream:2.6.0, akka-cluster-tools:2.6.0]

Which is also strange as I did not modify any of the dependencies...why does the sample project ship with incompatible versions for dependencies?

Anyways I noticed akka-persistence-query:2.5.23 is the offending one. it is version 2.5.23 instead of 2.6.0 like everyone else.

But there is no where akka-persistence-query is explicitly added. How then to correct the version?

Then the finally set of errors has to do with binding to ports:

java.lang.IllegalStateException: Failed to bind port 9042 on 127.0.0.1.
        at org.apache.cassandra.transport.Server.start(Server.java:160) ~[cassandra-bundle.jar:0.100-SNAPSHOT]
        at java.util.Collections$SingletonSet.forEach(Collections.java:4767) ~[na:1.8.0_161]

Not quite sure why this is error is occurring. Is it related to the prior version issue?

Well, I would appreciate insights from anyone more knowledeable than myself:

  1. Is changing the protocol URL actually the right thing to do?
  2. How to resolve the version incompatibility error?
  3. How to resolve the port error?
1
scalaakkaakka-cluster
I've logged an issue on github: github.com/akka/akka-distributed-workers-scala.g8/issues/17 - Levi Ramsey

1 Answers

1
votes

Ok, so after discussion with someone from Lightbend on the Gitter, It was discovered that the sample was temporary broken, and the upgrade to version 2.6.0 should not have been the case.

I modified the version to 2.5.26 and everything works fine.

An issue was opened to fix this here https://github.com/akka/akka-distributed-workers-scala.g8/issues/17