LibclusterGCE

This is a Google Compute Engine (GCE) clustering strategy for libcluster. It currently supports identifying nodes based on compute engine labels.

Installation

Add :libcluster_gce to your project's mix dependencies.

def deps do
  [
    {:libcluster_gce, "~> 0.0.1"}
  ]
end

Requirements

libcluster_gce requires Elixir 1.11+ & Erlang/OTP 22+

Deployment Assumptions

Clustering will only apply to nodes that are accessible via the GCP internal DNS. If this doesn't fit your deployment strategy, please open a Github issue describing your deployment configuration.

Configuration

To cluster an application running in Google Compute Engine, define a topology for libcluster.

# config.exs
config :libcluster,
  topologies: [
    my_app: [
      strategy: ClusterGCE.Strategy.Labels,
      config: [
        project: "my-project",
        labels: %{
          "env" => "prod"
        }
      ]
    ]
  ]

Make sure a cluster supervisor is part of your application.

defmodule MyApp.App do
  use Application

  def start(_type, _args) do
    topologies = Application.get_env(:libcluster, :topologies)

    children = [
      {Cluster.Supervisor, [topologies, [name: MyApp.ClusterSupervisor]]},
      # ...
    ]
    Supervisor.start_link(children, strategy: :one_for_one, name: MyApp.Supervisor)
  end
end

Update your release's vm.args file to include the following lines.

## Name of the node
-name <%= release_name%>@${GOOGLE_COMPUTE_ENGINE_INSTANCE}.${GOOGLE_COMPUTE_ENGINE_ZONE}.c.${GOOGLE_CLOUD_PROJECT}.internal

## Limit distributed erlang ports to a single port
-kernel inet_dist_listen_min 9999
-kernel inet_dist_listen_max 9999

Run your application with the environment variable REPLACE_OS_VARS=true and forward the following tcp ports:

• 4369 # epmd
• 9999 # erlang distribution

Thanks

Shout out to @alexgaribay for the hard work in libcluster_gae.

Authors

• Alex Kwiatkowski - alex+git@fremantle.io

License

libcluster_gce is released under the MIT license