Notify systemd when the service is ready or stopping

librepomgr/CMakeLists.txt

@@ -104,6 +104,17 @@ if (BOOST_ASIO_IO_URING)
     use_pkg_config_module(PKG_CONFIG_MODULES "liburing" VISIBILITY PUBLIC)
 endif ()
 
+# find systemd library
+option(SYSTEMD_SUPPORT "enable use of libsystemd for signaling when the service is ready" ON)
+if (SYSTEMD_SUPPORT)
+    message(STATUS "Using libsystemd")
+    set_property(
+        SOURCE serversetup.cpp webapi/server.cpp
+        APPEND
+        PROPERTY COMPILE_DEFINITIONS USE_LIBSYSTEMD)
+    use_pkg_config_module(PKG_CONFIG_MODULES "libsystemd" VISIBILITY PRIVATE)
+endif ()
+
 # find reflective-rapidjson
 find_package(reflective_rapidjson${CONFIGURATION_PACKAGE_SUFFIX} REQUIRED)
 use_reflective_rapidjson(VISIBILITY PUBLIC)

librepomgr/serversetup.cpp

@@ -35,6 +35,10 @@
 #include <sys/resource.h>
 #endif
 
+#ifdef USE_LIBSYSTEMD
+#include <systemd/sd-daemon.h>
+#endif
+
 #include <algorithm>
 #include <cerrno>
 #include <cstdlib>
@@ -768,6 +772,10 @@ void ServiceSetup::initStorage()
 
 int ServiceSetup::run()
 {
+#ifdef USE_LIBSYSTEMD
+    sd_notify(0, "STATUS=Loading databases");
+#endif
+
 #ifndef CPP_UTILITIES_DEBUG_BUILD
     try {
 #endif
@@ -793,12 +801,21 @@ int ServiceSetup::run()
 #endif
         printDatabases();
 
+#ifdef USE_LIBSYSTEMD
+        sd_notify(0, "STATUS=Initializing SSL");
+#endif
         cout << Phrases::SuccessMessage << "Initializing SSL" << Phrases::End;
         webServer.initSsl();
 
+#ifdef USE_LIBSYSTEMD
+        sd_notify(0, "STATUS=Allocating worker thread pool");
+#endif
         cout << Phrases::SuccessMessage << "Allocating worker thread pool (thread count: " << building.threadCount << ")" << Phrases::End;
         const auto buildWorker = building.allocateBuildWorker();
 
+#ifdef USE_LIBSYSTEMD
+        sd_notify(0, "STATUS=Starting web server");
+#endif
         cout << Phrases::SuccessMessage << "Starting web server (thread count: " << webServer.threadCount << "):" << TextAttribute::Reset
              << " http://" << webServer.address << ':' << webServer.port << endl;
         WebAPI::Server::serve(*this);

librepomgr/webapi/server.cpp

@@ -9,6 +9,10 @@
 
 #include <boost/asio/signal_set.hpp>
 
+#ifdef USE_LIBSYSTEMD
+#include <systemd/sd-daemon.h>
+#endif
+
 #include <iostream>
 #include <thread>
 
@@ -76,9 +80,19 @@ void Server::serve(ServiceSetup &setup)
         }
     });
 
+    // signal systemd that the service is ready
+#ifdef USE_LIBSYSTEMD
+    sd_notify(0, argsToString("READY=1\nSTATUS=Listening on http://", setup.webServer.address.to_string(), ':', setup.webServer.port).data());
+#endif
+
     // run the IO service on the requested number of threads
     const auto additionalThreads = ThreadPool("Web server", setup.webServer.ioContext, setup.webServer.threadCount - 1);
     setup.webServer.ioContext.run();
+
+    // signal systemd that the service is stopping
+#ifdef USE_LIBSYSTEMD
+    sd_notify(0, "STOPPING=1");
+#endif
 }
 
 void Server::stop()

srv/cmake/templates/systemd.service.in

@@ -3,6 +3,7 @@ Description=@SYSTEMD_SERVICE_DESCRIPTION@
 After=network.target
 
 [Service]
+Type=notify
 User=@SYSTEMD_SERVICE_USER_NAME@
 ExecStart=@SYSTEMD_SERVICE_EXEC@
 KillSignal=SIGQUIT