ConditionalChild - Start and stop processes conditionally (e.g. via feature flags)

[guisehn]

Announcing a tiny library called Conditional Child, that allows you to define directly in your supervision tree a condition for when a process should run. The condition is checked periodically, so it allows you to toggle processes in runtime.

A common use case is to manage processes using feature flags, but any condition can be used.

Example:

defmodule Demo.Application do
  @moduledoc false

  use Application

  @impl true
  def start(_type, _args) do
    children = [
      {ConditionalChild, child: Demo.Worker, start_if: fn -> your_condition() end}
    ]

    opts = [strategy: :one_for_one, name: Demo.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

Links:

• GitHub repo: GitHub - TheRealReal/conditional_child: A wrapper for starting and stopping a child process in runtime, based on periodic checks
• Hex docs: Conditional Child v0.1.1 — Documentation

[mindok]

That looks pretty handy, particularly during the development cycle where running internal “services” make a mess of the logs.