libcluster v2.5.0 Cluster.Strategy.DNSPoll

Assumes you have nodes that respond to the specified DNS query (A record), and which follow the node name pattern of <sname>@<ip-address>. If your setup matches those assumptions, this strategy will periodically poll DNS and connect all nodes it finds.

Options

poll_interval - How often to poll in milliseconds (optional; default: 5_000)
query - DNS query to use (required; e.g. “my-app.example.com”)
node_sname - The short name of the nodes you wish to connect to (required; e.g. “my-app”)

Usage

config :libcluster,
  topologies: [
    dns_poll_example: [
      strategy: Elixir.Cluster.Strategy.DNSPoll,
      config: [
        poll_interval: 5_000,
        query: "my-app.example.com",
        node_sname: "my-app"]]]

Link to this section Summary

Functions

child_spec(arg)

Returns a specification to start this module under a supervisor

init(opts)

Invoked when the server is started. start_link/3 or start/3 will block until it returns

start_link(opts)

Callback implementation for Cluster.Strategy.start_link/1

Link to this section Functions

child_spec(arg)

Returns a specification to start this module under a supervisor.

See Supervisor.

init(opts)

Invoked when the server is started. start_link/3 or start/3 will block until it returns.

args is the argument term (second argument) passed to start_link/3.

Returning {:ok, state} will cause start_link/3 to return {:ok, pid} and the process to enter its loop.

Returning {:ok, state, timeout} is similar to {:ok, state} except handle_info(:timeout, state) will be called after timeout milliseconds if no messages are received within the timeout.

Returning {:ok, state, :hibernate} is similar to {:ok, state} except the process is hibernated before entering the loop. See c:handle_call/3 for more information on hibernation.

Returning :ignore will cause start_link/3 to return :ignore and the process will exit normally without entering the loop or calling c:terminate/2. If used when part of a supervision tree the parent supervisor will not fail to start nor immediately try to restart the GenServer. The remainder of the supervision tree will be (re)started and so the GenServer should not be required by other processes. It can be started later with Supervisor.restart_child/2 as the child specification is saved in the parent supervisor. The main use cases for this are:

The GenServer is disabled by configuration but might be enabled later.
An error occurred and it will be handled by a different mechanism than the Supervisor. Likely this approach involves calling Supervisor.restart_child/2 after a delay to attempt a restart.

Returning {:stop, reason} will cause start_link/3 to return {:error, reason} and the process to exit with reason reason without entering the loop or calling c:terminate/2.

Callback implementation for GenServer.init/1.

start_link(opts)

Callback implementation for Cluster.Strategy.start_link/1.