Fork new process from previous daemon on reload.

The previously planned logic of forking a new daemon from the reload-process didn't work with
systemd: systemd does not allow long-running processes started from within the reload command.

Replaces parameter --reload with --reload-internal which is used when starting the new daemon.

Refs #5788

etc/init.d/icinga2.cmake

@@ -106,11 +106,13 @@ stop() {
 # Reload Icinga 2
 reload() {
 	printf "Reloading Icinga 2: "
-	if ! $DAEMON -c $ICINGA2_CONFIG_FILE -d --reload -e $ICINGA2_ERROR_LOG -u $ICINGA2_USER -g $ICINGA2_GROUP; then
-		echo "Error reloading Icinga."
-		exit 1
-	else
+
+	pid=`cat $ICINGA2_PID_FILE`
+	if kill -HUP $pid >/dev/null 2>&1; then
 		echo "Done"
+	else
+		echo "Error: Icinga not running"
+		exit 3
 	fi
 }
 

icinga-app/icinga.cpp

@@ -203,7 +203,7 @@ static void TerminateAndWaitForEnd(pid_t target)
 	while(Utility::GetTime() < timeout && (ret==0 || errno!=ESRCH))
 	{
 		Utility::Sleep(0.1);
-		ret = kill(target, 0);
+		ret = kill(target, SIGTERM);
 	}
 
 	// timeout and the process still seems to live: kill it
@@ -280,7 +280,7 @@ int Main(void)
 		("validate,C", "exit after validating the configuration")
 		("debug,x", "enable debugging")
 		("errorlog,e", po::value<std::string>(), "log fatal errors to the specified log file (only works in combination with --daemonize)")
-		("reload,r", "reload a running icinga instance")
+		("reload-internal", "used internally to implement config reload: do not call manually, send SIGHUP instead")
 #ifndef _WIN32
 		("daemonize,d", "detach from the controlling terminal")
 		("user,u", po::value<std::string>(), "user to run Icinga as")
@@ -434,15 +434,12 @@ int Main(void)
 		return EXIT_FAILURE;
 	}
 
-	pid_t runningpid = Application::ReadPidFile(Application::GetPidPath());
-	if (g_AppParams.count("reload")) {
-		if (runningpid < 0) {
-			Log(LogCritical, "icinga-app", "No instance of Icinga currently running: can't reload.");
+	if (!g_AppParams.count("validate") && !g_AppParams.count("reload-internal")) {
+		pid_t runningpid = Application::ReadPidFile(Application::GetPidPath());
+		if (runningpid >= 0) {
+			Log(LogCritical, "icinga-app", "Another instance of Icinga already running with PID " + Convert::ToString(runningpid));
 			return EXIT_FAILURE;
 		}
-	} else if (!g_AppParams.count("validate") && runningpid >= 0) {
-		Log(LogCritical, "icinga-app", "Another instance of Icinga already running at PID " + Convert::ToString(runningpid));
-		return EXIT_FAILURE;
 	}
 
 	if (!LoadConfigFiles(appType))
@@ -453,9 +450,9 @@ int Main(void)
 		return EXIT_SUCCESS;
 	}
 
-	if (g_AppParams.count("reload")) {
-		Log(LogInformation, "icinga-app", "Terminating previous instance of icinga (PID " + Convert::ToString(runningpid) + ")");
-		TerminateAndWaitForEnd(runningpid);
+	if(g_AppParams.count("reload-internal")) {
+		Log(LogInformation, "icinga-app", "Terminating previous instance of Icinga (PID " + Convert::ToString(Utility::GetParentPid()) + ")");
+		TerminateAndWaitForEnd(Utility::GetParentPid());
 		Log(LogInformation, "icinga-app", "Previous instance has ended, taking over now.");
 	}
 

lib/base/application.cpp

@@ -46,6 +46,7 @@ REGISTER_TYPE(Application);
 
 Application *Application::m_Instance = NULL;
 bool Application::m_ShuttingDown = false;
+bool Application::m_RequestRestart = false;
 bool Application::m_Restarting = false;
 bool Application::m_Debugging = false;
 int Application::m_ArgC;
@@ -219,7 +220,8 @@ void Application::RunEventLoop(void) const
 
 	double lastLoop = Utility::GetTime();
 
-	while (!m_ShuttingDown && !m_Restarting) {
+mainloop:
+	while (!m_ShuttingDown && !m_RequestRestart) {
 		/* Watches for changes to the system time. Adjusts timers if necessary. */
 		Utility::Sleep(2.5);
 
@@ -238,8 +240,21 @@ void Application::RunEventLoop(void) const
 		}
 
 		lastLoop = now;
-	}
 
+		if (m_RequestRestart) {
+			m_RequestRestart = false;         // we are now handling the request, once is enough
+		
+			// are we already restarting? ignore request if we already are
+			if (m_Restarting)
+				goto mainloop;
+
+			m_Restarting = true;
+			StartReloadProcess();
+
+			goto mainloop;
+		}
+	}
+	
 	Log(LogInformation, "base", "Shutting down Icinga...");
 	DynamicObject::StopObjects();
 	Application::GetInstance()->OnShutdown();
@@ -259,6 +274,33 @@ void Application::OnShutdown(void)
 	/* Nothing to do here. */
 }
 
+void Application::StartReloadProcess(void) const
+{
+	Log(LogInformation, "base", "Got reload command: Starting new instance.");
+
+	// prepare arguments
+	std::vector<String> args;
+	args.push_back(GetExePath(m_ArgV[0]));
+
+	for (int i=1; i < Application::GetArgC(); i++)
+		if (std::string(Application::GetArgV()[i]) != "--reload-internal")
+			args.push_back(Application::GetArgV()[i]);
+	args.push_back("--reload-internal");
+
+	Process::Ptr process = make_shared<Process>(args);
+
+	process->SetTimeout(15);
+
+	process->Run(boost::bind(&Application::ReloadProcessCallback, _1));
+}
+
+void Application::ReloadProcessCallback(const ProcessResult& pr)
+{
+	if (pr.ExitStatus != 0)
+		Log(LogCritical, "base", "Found error in config: reloading aborted");
+	m_Restarting=false;
+}
+
 /**
  * Signals the application to shut down during the next
  * execution of the event loop.
@@ -274,7 +316,7 @@ void Application::RequestShutdown(void)
  */
 void Application::RequestRestart(void)
 {
-	m_Restarting = true;
+	m_RequestRestart = true;
 }
 
 /**
@@ -563,29 +605,6 @@ int Application::Run(void)
 
 	result = Main();
 
-	if (m_Restarting) {
-		Log(LogInformation, "base", "Restarting application.");
-
-#ifndef _WIN32
-		String exePath = GetExePath(m_ArgV[0]);
-
-		int fdcount = getdtablesize();
-
-		for (int i = 3; i < fdcount; i++)
-			(void) close(i);
-
-		(void) execv(exePath.CStr(), m_ArgV);
-#else /* _WIN32 */
-		STARTUPINFO si;
-		PROCESS_INFORMATION pi;
-		memset(&si, 0, sizeof(si));
-		si.cb = sizeof(si);
-		CreateProcess(NULL, GetCommandLine(), NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi);
-#endif /* _WIN32 */
-
-		_exit(0);
-	}
-
 	return result;
 }
 

lib/base/application.h

@@ -24,6 +24,7 @@
 #include "base/application.th"
 #include "base/threadpool.h"
 #include "base/dynamicobject.h"
+#include "base/process.h"
 
 namespace icinga {
 
@@ -109,6 +110,8 @@ protected:
 
 	void RunEventLoop(void) const;
 
+	void StartReloadProcess(void) const;
+
 	virtual void OnShutdown(void);
 
 private:
@@ -116,6 +119,7 @@ private:
 
 	static bool m_ShuttingDown; /**< Whether the application is in the process of
 				  shutting down. */
+	static bool m_RequestRestart;
 	static bool m_Restarting;
 	static int m_ArgC; /**< The number of command-line arguments. */
 	static char **m_ArgV; /**< Command-line arguments. */
@@ -135,6 +139,8 @@ private:
 
 	static void SigAbrtHandler(int signum);
 	static void ExceptionHandler(void);
+
+	static void ReloadProcessCallback(const ProcessResult& pr);
 };
 
 }

lib/base/utility.cpp

@@ -331,6 +331,21 @@ pid_t Utility::GetPid(void)
 #endif /* _WIN32 */
 }
 
+/**
+ * Returns the ID of the parent process.
+ *
+ * @returns The PID.
+ */
+pid_t Utility::GetParentPid(void)
+{
+#ifndef _WIN32
+	return getppid();
+#else /* _WIN32 */
+	// TODO
+	return 0;
+#endif /* _WIN32 */
+}
+
 /**
  * Sleeps for the specified amount of time.
  *

lib/base/utility.h

@@ -74,6 +74,7 @@ public:
 	static double GetTime(void);
 
 	static pid_t GetPid(void);
+	static pid_t GetParentPid(void);
 
 	static void Sleep(double timeout);