Cron in Elixir Ref: https://dockyard.com/blog/2017/11/29/need-an-elixir-dependency-to-manage-recurring-jobs-not-so-fast

application.ex

defmodule KeycloakSync.Application do
  # See https://hexdocs.pm/elixir/Application.html
  # for more information on OTP Applications
  @moduledoc false

  use Application

  def start(_type, _args) do
    # List all child processes to be supervised
    import Supervisor.Spec

    children = [
      # Starts a worker by calling: KeycloakSync.Worker.start_link(arg)
      # {KeycloakSync.Worker, arg},
      supervisor(Cis.Repo, []),
      supervisor(Clsacom.Repo, []),
      supervisor(KeycloakSync.Repo, []),
      worker(KeycloakSync.Cron, [])
    ]

    # See https://hexdocs.pm/elixir/Supervisor.html
    # for other strategies and supported options
    opts = [strategy: :one_for_one, name: KeycloakSync.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

cron.ex

# my_app/lib/my_app/my_job/recurring_job.ex

defmodule MyApp.MyJob.RecurringJob do
  @moduledoc """
  Responsible of handling my job's schedule.

  * Runs job on start and every minute thereafter.
  """
  use GenServer
  alias MyApp.MyJob

  def start_link() do
    GenServer.start_link(__MODULE__, nil)
  end

  def init(_) do
    schedule_initial_job()
    {:ok, nil}
  end

  def handle_info(:perform, state) do
    MyJob.perform()
    schedule_next_job()
    {:noreply, state}
  end

  defp schedule_initial_job() do
    Process.send_after(self(), :perform, 5_000) # In 5 seconds
  end

  defp schedule_next_job() do
    Process.send_after(self(), :perform, 60_000) # In 60 seconds
  end
end