Intro

There's two things here: a cluster event logging extension and a visualizer. The visualizer is a work-in-progress and not yet functional.

Warning

All this stuff is experimental. Do not use in production.

Cluster Event Logging

This is an Akka extension that logs cluster events to a journal (via Akka Persistence). This extension contributes a route to Akka Management. The route simply returns the event stream.

Requirements

Akka Persistence Cassandra

Installation

To install, include this jar in your project.

Use:

object Main extends App {

  implicit val system = ActorSystem("system")

  AkkaManagement(system).start()

  // etc.

}

Get event stream

$ curl -XGET http://127.0.0.1:19999/events

data:{"self":{"address":{"protocol":"akka.tcp","system":"minimal","host":"127.0.0.1","port":2551}},"timestamp":1526144470504,"eventType":"MemberUp","event":{"member":{"uniqueAddress":{"address":{"protocol":"akka.tcp","system":"minimal","host":"127.0.0.1","port":2551}},"upNumber":1,"status":{},"roles":["dc-default"]}}}

data:{"self":{"address":{"protocol":"akka.tcp","system":"minimal","host":"127.0.0.1","port":2551}},"timestamp":1526144471232,"eventType":"LeaderChanged","event":{"leader":{"protocol":"akka.tcp","system":"minimal","host":"127.0.0.1","port":2551}}}

data:{"self":{"address":{"protocol":"akka.tcp","system":"minimal","host":"127.0.0.1","port":2551}},"timestamp":1526144491390,"eventType":"MemberLeft","event":{"member":{"uniqueAddress":{"address":{"protocol":"akka.tcp","system":"minimal","host":"127.0.0.1","port":2551}},"upNumber":1,"status":{},"roles":["dc-default"]}}}

data:{"self":{"address":{"protocol":"akka.tcp","system":"minimal","host":"127.0.0.1","port":2551}},"timestamp":1526144492053,"eventType":"MemberExited","event":{"member":{"uniqueAddress":{"address":{"protocol":"akka.tcp","system":"minimal","host":"127.0.0.1","port":2551}},"upNumber":1,"status":{},"roles":["dc-default"]}}}

Visualizer

The visualizer is a small scala.js program that displays the state of the cluster in a visual grid where led (i, j) highlights the state of node j as seen by node i. This representation is inspired by the Eric Loots' Pi-Akka-Cluster. This visualizer is not yet functional.