BoxTurtle.Runtime.Application.Helper (BoxTurtle v0.1.0)

Utilities for building an application's supervision tree.

Import the module in your Application and build the children list step by step:

defmodule MyApp.Application do
  use Application

  import BoxTurtle.Runtime.Application.Helper

  @impl true
  def start(_type, _args) do
    children =
      [MyApp.Repo]
      # A boolean, e.g. from config: config :my_app, start_web?: false
      |> conditional_append(Application.get_env(:my_app, :start_web?, true), MyAppWeb.Endpoint)
      # A function, called when the tree is built
      |> conditional_append(&MyApp.Features.workers_enabled?/0, [MyApp.Worker, MyApp.Scheduler])
      # A function with arguments
      |> conditional_append(&Code.ensure_loaded?/1, MyApp.Metrics, [Telemetry.Metrics])

    Supervisor.start_link(children, strategy: :one_for_one, name: MyApp.Supervisor)
  end
end

Summary

Types

condition()

A boolean, or a function returning one when applied to the args list.

Functions

conditional_append(current, condition, conditional, args \\ [])

Appends conditional (a single child or a list of children) to current when condition holds.