new(userspace/falco): added --config-schema action to print config schema.

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

userspace/falco/CMakeLists.txt

@@ -49,6 +49,7 @@ add_library(falco_application STATIC
   app/actions/validate_rules_files.cpp
   app/actions/create_requested_paths.cpp
   app/actions/close_inspectors.cpp
+  app/actions/print_config_schema.cpp
   configuration.cpp
   falco_outputs.cpp
   outputs_file.cpp

userspace/falco/app/actions/actions.h

@@ -38,6 +38,7 @@ falco::app::run_result list_plugins(const falco::app::state& s);
 falco::app::run_result load_config(const falco::app::state& s);
 falco::app::run_result load_plugins(falco::app::state& s);
 falco::app::run_result load_rules_files(falco::app::state& s);
+falco::app::run_result print_config_schema(falco::app::state& s);
 falco::app::run_result print_generated_gvisor_config(falco::app::state& s);
 falco::app::run_result print_help(falco::app::state& s);
 falco::app::run_result print_ignored_events(const falco::app::state& s);

userspace/falco/app/actions/print_config_schema.cpp

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: Apache-2.0
+/*
+Copyright (C) 2024 The Falco Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+#include "actions.h"
+
+using namespace falco::app;
+using namespace falco::app::actions;
+
+falco::app::run_result falco::app::actions::print_config_schema(falco::app::state &s)
+{
+	if(s.options.print_config_schema)
+	{
+		printf("%s", s.config->m_config_schema.dump(2).c_str());
+		return run_result::exit();
+	}
+	return run_result::ok();
+}

userspace/falco/app/app.cpp

@@ -60,6 +60,7 @@ bool falco::app::run(falco::app::state& s, bool& restart, std::string& errstr)
 	// dependencies are honored (e.g. don't process events before
 	// loading plugins, opening inspector, etc.).
 	std::list<app_action> run_steps = {
+		falco::app::actions::print_config_schema,
 		falco::app::actions::load_config,
 		falco::app::actions::print_help,
 		falco::app::actions::print_kernel_version,

userspace/falco/app/options.cpp

@@ -110,10 +110,11 @@ void options::define(cxxopts::Options& opts)
 	opts.add_options()
 		("h,help",                        "Print this help list and exit.", cxxopts::value(help)->default_value("false"))
 #ifdef BUILD_TYPE_RELEASE
-		("c",                             "Configuration file. If not specified uses " FALCO_INSTALL_CONF_FILE ".", cxxopts::value(conf_filename), "<path>")
+		("c",                             	"Configuration file. If not specified uses " FALCO_INSTALL_CONF_FILE ".", cxxopts::value(conf_filename), "<path>")
 #else
 		("c",                             "Configuration file. If not specified tries " FALCO_SOURCE_CONF_FILE ", " FALCO_INSTALL_CONF_FILE ".", cxxopts::value(conf_filename), "<path>")
 #endif
+		("config-schema",                 "Print the config json schema and exit.", cxxopts::value(print_config_schema)->default_value("false"))
 		("A",                             "Monitor all events supported by Falco and defined in rules and configs. Some events are ignored by default when -A is not specified (the -i option lists these events ignored). Using -A can impact performance. This option has no effect when reproducing events from a capture file.", cxxopts::value(all_events)->default_value("false"))
 		("b,print-base64",                "Print data buffers in base64. This is useful for encoding binary data that needs to be used over media designed to consume this format.")
 #if !defined(_WIN32) && !defined(__EMSCRIPTEN__) && !defined(MINIMAL_BUILD)

userspace/falco/app/options.h

@@ -40,6 +40,7 @@ public:
 
 	// Each of these maps directly to a command line option.
 	bool help = false;
+	bool print_config_schema = false;
 	std::string conf_filename;
 	bool all_events = false;
 	sinsp_evt::param_fmt event_buffer_format = sinsp_evt::PF_NORMAL;