Add feature flag to disable registration in prod by default.

config/config.exs

@@ -11,6 +11,11 @@ config :freedive,
   ecto_repos: [Freedive.Repo],
   generators: [timestamp_type: :utc_datetime]
 
+config :freedive,
+  features: [
+    register_account: true
+  ]
+
 # Configures the endpoint
 config :freedive, FreediveWeb.Endpoint,
   url: [host: "localhost"],

config/runtime.exs

@@ -21,6 +21,12 @@ if System.get_env("PHX_SERVER") do
 end
 
 if config_env() == :prod do
+  # Account registration in production is disabled by default.
+  # To enable, set the REGISTER_ACCOUNT_ENABLE environment variable to "true".
+  if System.get_env("REGISTER_ACCOUNT_ENABLE") != "true" do
+    config :freedive, :features, register_account: false
+  end
+
   database_path =
     System.get_env("DATABASE_PATH") ||
       raise """

lib/freedive/application.ex

@@ -25,7 +25,8 @@ defmodule Freedive.Application do
       # Start a worker by calling: Freedive.Worker.start_link(arg)
       # {Freedive.Worker, arg},
       # Start to serve requests, typically the last entry
-      FreediveWeb.Endpoint
+      FreediveWeb.Endpoint,
+      Freedive.Features
     ]
 
     children = if minimal, do: app_minimal, else: app_minimal ++ app_features

lib/freedive/features.ex

@@ -0,0 +1,45 @@
+defmodule Freedive.Features do
+  use GenServer
+  require Logger
+
+  def start_link(_args) do
+    GenServer.start_link(__MODULE__, nil, name: __MODULE__)
+  end
+
+  def enable(feature) do
+    GenServer.cast(__MODULE__, {:enable, feature})
+  end
+
+  def disable(feature) do
+    GenServer.cast(__MODULE__, {:disable, feature})
+  end
+
+  def enabled?(feature) do
+    GenServer.call(__MODULE__, {:enabled?, feature})
+  end
+
+  def init(nil) do
+    state = feature_flags_from_config()
+    Logger.info("Feature flags: #{inspect(state)}")
+    {:ok, state}
+  end
+
+  defp feature_flags_from_config() do
+    Application.get_env(:freedive, :features)
+  end
+
+  def handle_cast({:enable, feature}, state) do
+    Logger.info("Enabling feature: #{feature}")
+    {:noreply, Keyword.put(state, feature, true)}
+  end
+
+  def handle_cast({:disable, feature}, state) do
+    Logger.info("Disabling feature: #{feature}")
+    {:noreply, Keyword.put(state, feature, false)}
+  end
+
+  def handle_call({:enabled?, feature}, _from, state) do
+    enabled = Keyword.get(state, feature, false)
+    {:reply, enabled, state}
+  end
+end

lib/freedive_web/live/user_registration_live.ex

@@ -3,8 +3,10 @@ defmodule FreediveWeb.UserRegistrationLive do
 
   alias Freedive.Accounts
   alias Freedive.Accounts.User
+  alias Freedive.Features
 
   def render(assigns) do
+    if Features.enabled?(:register_account) do
       ~H"""
       <div class="mx-auto max-w-sm">
         <.header class="text-center">
@@ -40,6 +42,18 @@ defmodule FreediveWeb.UserRegistrationLive do
         </.simple_form>
       </div>
       """
+    else
+      ~H"""
+      <.section>
+        <.title>
+          Sorry!
+        </.title>
+        <.subtitle>
+          Registration is closed.
+        </.subtitle>
+      </.section>
+      """
+    end
   end
 
   def mount(_params, _session, socket) do
@@ -54,6 +68,7 @@ defmodule FreediveWeb.UserRegistrationLive do
   end
 
   def handle_event("save", %{"user" => user_params}, socket) do
+    if Features.enabled?(:register_account) do
       case Accounts.register_user(user_params) do
         {:ok, user} ->
           {:ok, _} =
@@ -68,6 +83,9 @@ defmodule FreediveWeb.UserRegistrationLive do
         {:error, %Ecto.Changeset{} = changeset} ->
           {:noreply, socket |> assign(check_errors: true) |> assign_form(changeset)}
       end
+    else
+      {:noreply, socket}
+    end
   end
 
   def handle_event("validate", %{"user" => user_params}, socket) do

test/freedive_web/live/user_registration_live_test.exs

@@ -1,9 +1,22 @@
 defmodule FreediveWeb.UserRegistrationLiveTest do
   use FreediveWeb.ConnCase
+  alias Freedive.Features
 
   import Phoenix.LiveViewTest
   import Freedive.AccountsFixtures
 
+  describe "Registration closed" do
+    test "shows registrations closed message", %{conn: conn} do
+      Features.disable(:register_account)
+
+      {:ok, _lv, html} = live(conn, ~p"/users/register")
+
+      assert html =~ "Registration is closed"
+
+      Features.enable(:register_account)
+    end
+  end
+
   describe "Registration page" do
     test "renders registration page", %{conn: conn} do
       {:ok, _lv, html} = live(conn, ~p"/users/register")