Galaxy

This library provides a mechanism for automatically forming clusters of Erlang nodes, with either static or dynamic node membership. It provides a publish/subscribe mechanism for cluster events so that you can easily be notified when cluster members join or leave with a variety of strategies provided out of the box.

You can find supporting documentation here.

Features

• Automatic cluster formation/healing
• Choice of multiple clustering strategies out of the box:
  • Standard Distributed Erlang facilities (e.g. .hosts.erlang), which supports IP-based or DNS-based names
  • DNS via its metadata API using via a configurable label selector and node basename; or alternatively, using DNS.
• Easy to provide your own custom clustering strategies for your specific environment.
• Easy to use provide your own distribution plumbing (i.e. something other than Distributed Erlang), by implementing a small set of callbacks. This allows galaxy to support projects like Partisan.

Installation

defp deps do
  [{:galaxy, github: "~> 0.3"}]
end

Usage

It is easy to get started using galaxy, start the module in the supervision tree of an application in your Elixir system. And configure the it using:

# In your config/releases.exs file
headless_service =
  System.get_env("SERVICE_NAME") ||
    raise """
    environment variable SERVICE_NAME is missing.
    You can retrieve a headless service using a StatefulSets
    """

config :cruise, Cruise.Cluster,
  services: [headless_service],
  polling: 10_000

# In your application code
defmodule MyApp.Cluster do
  use Galaxy.Cluster,
    otp_app: :my_app,
    topology: Galaxy.Topology.ErlDist
end

The following section describes topology configuration in more detail.

Clustering

You have a handful of choices with regards to cluster management out of the box:

• Galaxy.Host, which uses the .hosts.erlang file to determine which hosts to connect to.
• Galaxy.DNS, which query the DNS server based on the services configuration.

License

MIT