Simple DNS clustering for distributed Elixir nodes.

The package can be installed by adding dns_cluster to your list of dependencies in mix.exs:

def deps do
  [
    {:dns_cluster, "~> 0.1.1"}
  ]
end

Next, you can configure and start the cluster by adding it to your supervision tree in your application.ex:

children = [
  {Phoenix.PubSub, ...},
  {DNSCluster, query: Application.get_env(:my_app, :dns_cluster_query) || :ignore},
  MyAppWeb.Endpoint
]

If you are deploying with Elixir releases, the release must be set to support longnames and the node must be named. These can be set in your rel/env.sh.eex file:

#!/bin/sh
export RELEASE_DISTRIBUTION=name
export RELEASE_NODE="myapp@fully-qualified-host-or-ip"

By default, nodes from the same release will have the same cookie. If you want different applications or releases to connect to each other, then you must set the RELEASE_COOKIE, either in your deployment platform or inside rel/env.sh.eex:

#!/bin/sh
...
export RELEASE_COOKIE="my-app-cookie"