chore(userspace/falco): deprecate old 'rules_file' config key.

Signed-off-by: Federico Di Pierro <nierro92@gmail.com>

falco.yaml

@@ -28,7 +28,7 @@
 # Falco config files
 #     configs_files
 # Falco rules files
-#     rules_file
+#     rules_files
 # Falco engine
 #     engine
 # Falco plugins
@@ -128,7 +128,7 @@
 # Therefore, loaded config files *can* override values from main config file.
 # Also, nested include is not allowed, ie: included config files won't be able to include other config files.
 #
-# Like for 'rules_file', specifying a folder will load all the configs files present in it in a lexicographical order.
+# Like for 'rules_files', specifying a folder will load all the configs files present in it in a lexicographical order.
 configs_files:
   - /etc/falco/config.d
 
@@ -136,11 +136,12 @@ configs_files:
 # Falco rules files #
 #####################
 
-# [Stable] `rules_file`
+# [Stable] `rules_files`
 #
 # Falco rules can be specified using files or directories, which are loaded at
-# startup. The name "rules_file" is maintained for backwards compatibility. If
+# startup. The old name "rules_file" is maintained for backwards compatibility.
-# the entry is a file, it will be read directly. If the entry is a directory,
+#
+# If the entry is a file, it will be read directly. If the entry is a directory,
 # all files within that directory will be read in alphabetical order.
 #
 # The falco_rules.yaml file ships with the Falco package and is overridden with
@@ -169,7 +170,7 @@ configs_files:
 # "first match wins" principle. However, enabling the `all` matching option may result
 # in a performance penalty. We recommend carefully testing this alternative setting  
 # before deploying it in production. Read more under the `rule_matching` configuration.
-rules_file:
+rules_files:
   - /etc/falco/falco_rules.yaml
   - /etc/falco/falco_rules.local.yaml
   - /etc/falco/rules.d

userspace/falco/configuration.cpp

@@ -167,6 +167,18 @@ void falco_configuration::merge_configs_files(const std::string& config_name, st
 	}
 }
 
+void falco_configuration::init_logger()
+{
+	m_log_level = config.get_scalar<std::string>("log_level", "info");
+	falco_logger::set_level(m_log_level);
+	falco_logger::set_sinsp_logging(
+		config.get_scalar<bool>("libs_logger.enabled", false),
+		config.get_scalar<std::string>("libs_logger.severity", "debug"),
+		"[libs]: ");
+	falco_logger::log_stderr = config.get_scalar<bool>("log_stderr", false);
+	falco_logger::log_syslog = config.get_scalar<bool>("log_syslog", true);
+}
+
 void falco_configuration::load_engine_config(const std::string& config_name)
 {
 	// Set driver mode if not already set.
@@ -238,12 +250,28 @@ void falco_configuration::load_engine_config(const std::string& config_name)
 
 void falco_configuration::load_yaml(const std::string& config_name)
 {
+	init_logger();
 	load_engine_config(config_name);
-	m_log_level = config.get_scalar<std::string>("log_level", "info");
 
 	std::list<std::string> rules_files;
 
+	// Small glue code to support old deprecated 'rules_file' config key.
+	int num_rules_files_opts = 0;
+	if (config.is_defined("rules_files"))
+	{
+		num_rules_files_opts++;
+		config.get_sequence<std::list<std::string>>(rules_files, std::string("rules_files"));
+	}
+	if (config.is_defined("rules_file"))
+	{
+		num_rules_files_opts++;
 		config.get_sequence<std::list<std::string>>(rules_files, std::string("rules_file"));
+		falco_logger::log(falco_logger::level::WARNING, "Using deprecated config key 'rules_file'. Please use new 'rules_files' config key.");
+	}
+	if (num_rules_files_opts == 2)
+	{
+		throw std::logic_error("Error reading config file (" + config_name + "): both 'rules_files' and 'rules_file' keys set");
+	}
 
 	m_rules_filenames.clear();
 	m_loaded_rules_filenames.clear();
@@ -393,19 +421,6 @@ void falco_configuration::load_yaml(const std::string& config_name)
 		m_outputs.push_back(grpc_output);
 	}
 
-	m_log_level = config.get_scalar<std::string>("log_level", "info");
-
-	falco_logger::set_level(m_log_level);
-
-
-	falco_logger::set_sinsp_logging(
-		config.get_scalar<bool>("libs_logger.enabled", false),
-		config.get_scalar<std::string>("libs_logger.severity", "debug"),
-		"[libs]: ");
-
-	falco_logger::log_stderr = config.get_scalar<bool>("log_stderr", false);
-	falco_logger::log_syslog = config.get_scalar<bool>("log_syslog", true);
-
 	m_output_timeout = config.get_scalar<uint32_t>("output_timeout", 2000);
 
 	std::string rule_matching = config.get_scalar<std::string>("rule_matching", "first");

userspace/falco/configuration.h

@@ -173,13 +173,10 @@ public:
 
 private:
 	void merge_configs_files(const std::string& config_name, std::vector<std::string>& loaded_config_files);
-
 	void load_yaml(const std::string& config_name);
-
+	void init_logger();
 	void load_engine_config(const std::string& config_name);
-
 	void init_cmdline_options(const std::vector<std::string>& cmdline_options);
-
 	/**
 	 * Given a <key>=<value> specifier, set the appropriate option
 	 * in the underlying yaml config. <key> can contain '.'