ha-handler/lib/ha_handler/pgsql/supervisor.ex

defmodule HAHandler.PGSQL.Supervisor do
  use Supervisor

  alias HAHandler.PGSQL.Watcher, as: PGSQLWatcher

  def start_link(opts) do
    Supervisor.start_link(__MODULE__, opts, name: __MODULE__)
  end

  @impl true
  def init(instances) do
    children =
      Enum.map(instances, fn conf ->
        %{
          id: Keyword.get(conf, :hostname),
          start: {PGSQLWatcher, :start_link, [conf]}
        }
      end)

    opts = [strategy: :one_for_one]
    Supervisor.init(children, opts)
  end
end