Add env var for disabling token auth (#696)

README.md

@@ -174,6 +174,9 @@ The following environment variables configure Livebook:
     long and it can be generated by commands such as: 'openssl rand -base64 48'.
     Defaults to a random secret on every boot.
 
+  * LIVEBOOK_TOKEN_ENABLED - controls whether token authentication is enabled.
+    Enabled by default unless `LIVEBOOK_PASSWORD` is set.
+
 <!-- Environment variables -->
 
 If running Livebook as a Docker image or an Elixir release, [the environment

lib/livebook.ex

@@ -31,10 +31,15 @@ defmodule Livebook do
       config :livebook, LivebookWeb.Endpoint, http: [ip: ip]
     end
 
-    if password = Livebook.Config.password!("LIVEBOOK_PASSWORD") do
-      config :livebook, authentication_mode: :password, password: password
-    else
-      config :livebook, token: Livebook.Utils.random_id()
+    cond do
+      password = Livebook.Config.password!("LIVEBOOK_PASSWORD") ->
+        config :livebook, authentication_mode: :password, password: password
+
+      Livebook.Config.token_enabled!("LIVEBOOK_TOKEN_ENABLED") ->
+        config :livebook, token: Livebook.Utils.random_id()
+
+      true ->
+        config :livebook, authentication_mode: :disabled
     end
 
     if runtime = Livebook.Config.default_runtime!("LIVEBOOK_DEFAULT_RUNTIME") do

lib/livebook/config.ex

@@ -168,6 +168,13 @@ defmodule Livebook.Config do
     end
   end
 
+  @doc """
+  Parses token auth setting from env.
+  """
+  def token_enabled!(env) do
+    System.get_env(env, "1") in ~w(true 1)
+  end
+
   @doc """
   Parses and validates default runtime from env.
   """