From d2e875a94f29bfd0a94954b35d1d714c8ee75662 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonatan=20K=C5=82osko?= <jonatanklosko@gmail.com>
Date: Mon, 23 Oct 2023 20:01:05 +0200
Subject: [PATCH] Add env var for debug logs (#2292)

---
 README.md              |  3 +++
 lib/livebook.ex        |  4 ++++
 lib/livebook/config.ex | 13 +++++++++++++
 3 files changed, 20 insertions(+)

diff --git a/README.md b/README.md
index 9215cdc01..38e7450c0 100644
--- a/README.md
+++ b/README.md
@@ -224,6 +224,9 @@ The following environment variables can be used to configure Livebook on boot:
     configuration. Defaults to "livebook" under the default user data
     directory.
 
+  * LIVEBOOK_DEBUG - enables verbose logging, when set to "true". Disabled
+    by default.
+
   * LIVEBOOK_DEFAULT_RUNTIME - sets the runtime type that is used by default
     when none is started explicitly for the given notebook. Must be either
     "standalone" (Elixir standalone), "attached:NODE:COOKIE" (Attached node)
diff --git a/lib/livebook.ex b/lib/livebook.ex
index 671d62925..3f3807296 100644
--- a/lib/livebook.ex
+++ b/lib/livebook.ex
@@ -91,6 +91,10 @@ defmodule Livebook do
         Livebook.Config.secret!("LIVEBOOK_SECRET_KEY_BASE") ||
           Base.encode64(:crypto.strong_rand_bytes(48))
 
+    if Livebook.Config.debug!("LIVEBOOK_DEBUG") do
+      config :logger, level: :debug
+    end
+
     if port = Livebook.Config.port!("LIVEBOOK_PORT") do
       config :livebook, LivebookWeb.Endpoint, http: [port: port]
     end
diff --git a/lib/livebook/config.ex b/lib/livebook/config.ex
index f3dc1dc14..c74f3cf2a 100644
--- a/lib/livebook/config.ex
+++ b/lib/livebook/config.ex
@@ -420,6 +420,19 @@ defmodule Livebook.Config do
     end
   end
 
+  @doc """
+  Parses and validates debug mode from env.
+  """
+  def debug!(env) do
+    if debug = System.get_env(env) do
+      cond do
+        debug in ["1", "true"] -> true
+        debug in ["0", "false"] -> false
+        true -> abort!("expected #{env} to be a boolean, got: #{inspect(debug)}")
+      end
+    end
+  end
+
   @doc """
   Parses and validates the port from env.
   """