Load log levels from environment variables

nano/lib/logging.cpp

@@ -269,22 +269,32 @@ spdlog::level::level_enum nano::to_spdlog_level (nano::log::level level)
 
 nano::log_config nano::log_config::cli_default ()
 {
-	log_config config;
+	log_config config{};
 	config.default_level = nano::log::level::critical;
+	config.console.to_cerr = true; // Use cerr to avoid interference with CLI output that goes to stdout
+	config.file.enable = false;
 	return config;
 }
 
 nano::log_config nano::log_config::daemon_default ()
 {
-	log_config config;
+	log_config config{};
 	config.default_level = nano::log::level::info;
 	return config;
 }
 
 nano::log_config nano::log_config::tests_default ()
 {
-	log_config config;
-	config.default_level = nano::log::level::critical;
+	log_config config{};
+	config.default_level = nano::log::level::off;
+	return config;
+}
+
+nano::log_config nano::log_config::sample_config ()
+{
+	log_config config{};
+	config.default_level = nano::log::level::info;
+	config.levels = default_levels (nano::log::level::info); // Populate with default levels
 	return config;
 }
 
@@ -349,7 +359,7 @@ void nano::log_config::deserialize (nano::tomlconfig & toml)
 	if (toml.has_key ("default_level"))
 	{
 		auto default_level_l = toml.get<std::string> ("default_level");
-		default_level = nano::log::to_level (default_level_l);
+		default_level = nano::log::parse_level (default_level_l);
 	}
 
 	if (toml.has_key ("console"))
@@ -376,7 +386,7 @@ void nano::log_config::deserialize (nano::tomlconfig & toml)
 			try
 			{
 				auto & [name_str, level_str] = level;
-				auto logger_level = nano::log::to_level (level_str);
+				auto logger_level = nano::log::parse_level (level_str);
 				auto logger_id = parse_logger_id (name_str);
 
 				levels[logger_id] = logger_level;
@@ -399,14 +409,14 @@ nano::log_config::logger_id_t nano::log_config::parse_logger_id (const std::stri
 	auto pos = logger_name.find ("::");
 	if (pos == std::string::npos)
 	{
-		return { nano::log::to_type (logger_name), nano::log::detail::all };
+		return { nano::log::parse_type (logger_name), nano::log::detail::all };
 	}
 	else
 	{
 		auto logger_type = logger_name.substr (0, pos);
 		auto logger_detail = logger_name.substr (pos + 1);
 
-		return { nano::log::to_type (logger_type), nano::log::to_detail (logger_detail) };
+		return { nano::log::parse_type (logger_type), nano::log::parse_detail (logger_detail) };
 	}
 }
 
@@ -430,6 +440,62 @@ nano::log_config nano::load_log_config (nano::log_config fallback, const std::fi
 	try
 	{
 		auto config = nano::load_config_file<nano::log_config> (fallback, config_filename, data_path, config_overrides);
+
+		// Parse default log level from environment variable, e.g. "NANO_LOG=debug"
+		auto env_level = nano::get_env ("NANO_LOG");
+		if (env_level)
+		{
+			try
+			{
+				config.default_level = nano::log::parse_level (*env_level);
+
+				std::cerr << "Using default log level from NANO_LOG environment variable: " << *env_level << std::endl;
+			}
+			catch (std::invalid_argument const & ex)
+			{
+				std::cerr << "Invalid log level from NANO_LOG environment variable: " << ex.what () << std::endl;
+			}
+		}
+
+		// Parse per logger levels from environment variable, e.g. "NANO_LOG_LEVELS=ledger=debug,node=trace"
+		auto env_levels = nano::get_env ("NANO_LOG_LEVELS");
+		if (env_levels)
+		{
+			std::map<nano::log_config::logger_id_t, nano::log::level> levels;
+			for (auto const & env_level_str : nano::util::split (*env_levels, ','))
+			{
+				try
+				{
+					// Split 'logger_name=level' into a pair of 'logger_name' and 'level'
+					auto arr = nano::util::split (env_level_str, '=');
+					if (arr.size () != 2)
+					{
+						throw std::invalid_argument ("Invalid entry: " + env_level_str);
+					}
+
+					auto name_str = arr[0];
+					auto level_str = arr[1];
+
+					auto logger_id = nano::log_config::parse_logger_id (name_str);
+					auto logger_level = nano::log::parse_level (level_str);
+
+					levels[logger_id] = logger_level;
+
+					std::cerr << "Using logger log level from NANO_LOG_LEVELS environment variable: " << name_str << "=" << level_str << std::endl;
+				}
+				catch (std::invalid_argument const & ex)
+				{
+					std::cerr << "Invalid log level from NANO_LOG_LEVELS environment variable: " << ex.what () << std::endl;
+				}
+			}
+
+			// Merge with existing levels
+			for (auto const & [logger_id, level] : levels)
+			{
+				config.levels[logger_id] = level;
+			}
+		}
+
 		return config;
 	}
 	catch (std::runtime_error const & ex)

nano/lib/logging.hpp

@@ -27,7 +27,7 @@ public:
 	nano::log::level flush_level{ nano::log::level::error };
 
 	using logger_id_t = std::pair<nano::log::type, nano::log::detail>;
-	std::map<logger_id_t, nano::log::level> levels{ default_levels (default_level) };
+	std::map<logger_id_t, nano::log::level> levels;
 
 	struct console_config
 	{
@@ -50,10 +50,11 @@ public: // Predefined defaults
 	static log_config cli_default ();
 	static log_config daemon_default ();
 	static log_config tests_default ();
+	static log_config sample_config (); // For auto-generated sample config files
+
+	static logger_id_t parse_logger_id (std::string const &);
 
 private:
-	logger_id_t parse_logger_id (std::string const &);
-
 	/// Returns placeholder log levels for all loggers
 	static std::map<logger_id_t, nano::log::level> default_levels (nano::log::level);
 };

nano/lib/logging_enums.cpp

@@ -47,7 +47,7 @@ const std::vector<nano::log::type> & nano::log::all_types ()
 	return all;
 }
 
-nano::log::level nano::log::to_level (std::string_view name)
+nano::log::level nano::log::parse_level (std::string_view name)
 {
 	auto value = magic_enum::enum_cast<nano::log::level> (name);
 	if (value.has_value ())
@@ -64,7 +64,7 @@ nano::log::level nano::log::to_level (std::string_view name)
 	}
 }
 
-nano::log::type nano::log::to_type (std::string_view name)
+nano::log::type nano::log::parse_type (std::string_view name)
 {
 	auto value = magic_enum::enum_cast<nano::log::type> (name);
 	if (value.has_value ())
@@ -77,7 +77,7 @@ nano::log::type nano::log::to_type (std::string_view name)
 	}
 }
 
-nano::log::detail nano::log::to_detail (std::string_view name)
+nano::log::detail nano::log::parse_detail (std::string_view name)
 {
 	auto value = magic_enum::enum_cast<nano::log::detail> (name);
 	if (value.has_value ())

nano/lib/logging_enums.hpp

@@ -129,13 +129,13 @@ std::string_view to_string (nano::log::detail);
 std::string_view to_string (nano::log::level);
 
 /// @throw std::invalid_argument if the input string does not match a log::level
-nano::log::level to_level (std::string_view);
+nano::log::level parse_level (std::string_view);
 
 /// @throw std::invalid_argument if the input string does not match a log::type
-nano::log::type to_type (std::string_view);
+nano::log::type parse_type (std::string_view);
 
 /// @throw std::invalid_argument if the input string does not match a log::detail
-nano::log::detail to_detail (std::string_view);
+nano::log::detail parse_detail (std::string_view);
 
 std::vector<nano::log::level> const & all_levels ();
 std::vector<nano::log::type> const & all_types ();

nano/lib/utility.hpp

@@ -245,6 +245,18 @@ std::string join (Container const & container, std::string_view delimiter, Func
 	return join (container.begin (), container.end (), delimiter, transform);
 }
 
+inline std::vector<std::string> split (const std::string & str, char delimiter)
+{
+	std::stringstream ss{ str };
+	std::vector<std::string> result;
+	std::string item;
+	while (std::getline (ss, item, delimiter))
+	{
+		result.push_back (item);
+	}
+	return result;
+}
+
 template <class T>
 std::string to_str (T const & val)
 {

nano/node/cli.cpp

@@ -674,7 +674,7 @@ std::error_code nano::handle_node_options (boost::program_options::variables_map
 		else if (type == "log")
 		{
 			valid_type = true;
-			nano::log_config config{ nano::log_config::daemon_default () };
+			nano::log_config config = nano::log_config::sample_config ();
 			config.serialize_toml (toml);
 		}
 		else if (type == "tls")