Libelection

Library to perform leader election in a cluster of containerized Elixir nodes.

Installation

def deps do
  [{:libelection, "~> 1.1.0"}]
end

Usage

if Election.leader? do
  # Code path executed only by the leader node
else
  # Code path executed by followers
end

How it works

Polls the API of the configured container orchestration platform to determine the oldest node of the cluster.

To configure the polling interval use:

config :libelection, :polling_interval, 2_000 # 2 seconds

To configure the function which lists the node of the cluster use:

config :libelection, :list_nodes, {module, function, args}
# it can also be a function reference
config :libelection, :list_nodes, &SomeModule.some_function/1

Configure the logger

config :libelection, :logger, %{level: :debug} # Default

Note: The configuration also supports confex style configurations.

Election Strategies

Rancher

The create_index identifier is used to pick the leader.

config :libelection,
  strategy: Election.Strategy.Rancher,
  rancher_node_basename: "some-app"

Kubernetes

The resourceVersion identifier is used to pick the leader.

config :libelection,
  strategy: Election.Strategy.Kubernetes,
  kubernetes_selector: "app=some-app",
  kubernetes_node_basename: "some-app"

Documentation

• exdoc
• wiki (coming soon)

License

GPLv3