VILLASnode/lib/api/requests/restart.cpp

/** The "restart" API request.
 *
 * @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
 * @copyright 2014-2020, Institute for Automation of Complex Power Systems, EONERC
 * @license GNU General Public License (version 3)
 *
 * VILLASnode
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************************/

#include <villas/super_node.hpp>
#include <villas/log.hpp>
#include <villas/node/exceptions.hpp>
#include <villas/utils.hpp>
#include <villas/api/request.hpp>
#include <villas/api/response.hpp>
#include <villas/api/session.hpp>

namespace villas {
namespace node {
namespace api {

class RestartRequest : public Request {

protected:
	static std::string configUri;

	static void handler()
	{
		int ret;
		const char *cfg = !configUri.empty()
				    ? configUri.c_str()
				    : nullptr;

		const char *argv[] = { "villas-node", cfg, nullptr };

		Logger logger = logging.get("api");

		logger->info("Restart instance: config={}", cfg);

		ret = execvp("/proc/self/exe", (char **) argv);
		if (ret)
			throw SystemError("Failed to restart");
	}

public:
	using Request::Request;

	virtual Response * execute()
	{
		int ret;
		json_error_t err;

		if (method != Session::Method::POST)
			throw InvalidMethod(this);

		json_t *json_config = nullptr;

		if (body) {
			ret = json_unpack_ex(body, &err, 0, "{ s?: o }",
				"config", &json_config
			);
			if (ret < 0)
				throw BadRequest("Failed to parse request body");
		}

		if (json_config) {
			if (json_is_string(json_config))
				configUri = json_string_value(json_config);
			else if (json_is_object(json_config)) {
				char configUriBuf[] = "villas-node.json.XXXXXX";
				int configFd = mkstemp(configUriBuf);

				FILE *configFile = fdopen(configFd, "w+");

				ret = json_dumpf(json_config, configFile, JSON_INDENT(4));
				if (ret < 0)
					throw Error(HTTP_STATUS_INTERNAL_SERVER_ERROR, "Failed to create temporary config file");

				fclose(configFile);
				configUri = configUriBuf;
			}
			else if (json_config != nullptr)
				throw BadRequest("Parameter 'config' must be either a URL (string) or a configuration (object)");
		}
		else	/* If no config is provided via request, we will use the previous one */
			configUri = session->getSuperNode()->getConfigUri();

		logger->info("Restarting to {}", configUri.c_str());

		/* Increment API restart counter */
		char *scnt = getenv("VILLAS_API_RESTART_COUNT");
		int cnt = scnt ? atoi(scnt) : 0;
		char buf[32];
		snprintf(buf, sizeof(buf), "%d", cnt + 1);

		/* We pass some env variables to the new process */
		setenv("VILLAS_API_RESTART_COUNT", buf, 1);

		auto *json_response = json_pack("{ s: i, s: o }",
			"restarts", cnt,
			"config", configUri.empty()
			            ? json_null()
				    : json_string(configUri.c_str())
		);

		/* Register exit handler */
		ret = atexit(handler);
		if (ret)
			throw Error(HTTP_STATUS_INTERNAL_SERVER_ERROR, "Failed to restart VILLASnode instance");

		/* Properly terminate current instance */
		utils::killme(SIGTERM);

		return new JsonResponse(session, HTTP_STATUS_OK, json_response);
	}
};

std::string RestartRequest::configUri;

/* Register API request */
static char n[] = "restart";
static char r[] = "/restart";
static char d[] = "restart VILLASnode with new configuration";
static RequestPlugin<RestartRequest, n, r, d> p;

} /* namespace api */
} /* namespace node */
} /* namespace villas */