riak_core cluster formation

riak_core_cluster_formation.md

riak_core cluster formation

Set up libcluster

Use libcluster to set up cluster automatically.

Add dependency in mix.exs and run mix deps.get:

defp deps do
  [
    # ...
    {:libcluster, "~> 3.3"}
    # ...
  ]
end

Add Cluster.Supervisor process in the supervision tree of the app (usually in lib/appname/application.ex):

defmodule MyApp.App do
  use Application

  def start(_type, _args) do
    topologies = [
      local_udp_gossip_aja: [
        strategy: Cluster.Strategy.Gossip,
        config: [
          secret: "this_is_a_shared_secret"
        ]
      ]
    ]

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

Running

Run 3 nodes:

MIX_ENV=node1 iex --name [email protected] --cookie this_is_a_shared_secret -S mix
MIX_ENV=node2 iex --name [email protected] --cookie this_is_a_shared_secret -S mix
MIX_ENV=node3 iex --name [email protected] --cookie this_is_a_shared_secret -S mix

On node2 and node3 run:

:riak_core.join('[email protected]')

On node1 run:

# To see the planned changes in the ring:
:riak_core_claimant.plan()

# Now we can commit the plan:
:riak_core_claimant.commit()

# Periodically run some of these:

:riak_core_console.member_status([])

:riak_core_handoff_manager.status()

:riak_core_console.transfers([])

{:ok, ring} = :riak_core_ring_manager.get_my_ring()
:riak_core_ring.pretty_print(ring, [:legend])

:riak_core_status.ringready()

Todo: automatically admit new node to riak core cluster using something like Horde's NodeListener