hacst · June 5, 2018 23:18 · Jun 5, 2018
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -0,0 +1,5 @@
+cmake_minimum_required(VERSION 2.8)
+project(sdnotify)
+
+add_executable(sdnotify sdnotify.cpp)
+target_link_libraries(sdnotify PUBLIC systemd)
diff --git a/sdnotify.cpp b/sdnotify.cpp
@@ -0,0 +1,33 @@
+#include <systemd/sd-daemon.h>
+#include <stdio.h>
+#include <unistd.h>
+
+int main()
+{
+    setbuf(stdout, NULL);
+
+    uint64_t watchdogIntervalInUs;
+    const bool watchdog = sd_watchdog_enabled(0, &watchdogIntervalInUs) > 0; // Service WatchdogSec must be set for this to return > 0
+    if (watchdog) {
+        printf("Watchdog is enabled with %lu us\n", watchdogIntervalInUs);
+    } else {
+        printf("Not running in a watchdog env\n");
+        return 1;
+    }
+
+    // To be able to use sd_notify at all have to set service NotifyAccess (e.g. to main)
+    sd_notify(0, "READY=1"); // If service Type=notify the service is only considered ready once we send this (this is independent of watchdog capability)
+    printf("Notified as ready. Now sleeping with watchdog\n");
+
+    //usleep(watchdogIntervalInUs * 2); // Should get the process killed
+
+    int i = 0;
+    while(true) {
+        usleep(watchdogIntervalInUs / 2); // Recommended reporting interval is half the watchdog interval
+        sd_notify(0, "WATCHDOG=1");
+        sd_notifyf(0, "STATUS=Watchdog notify count %d", i); // Visible in systemctl status
+        ++i;
+    }
+
+    return 0;
+}
diff --git a/sdnotify.service b/sdnotify.service
@@ -0,0 +1,9 @@
+[Unit]
+Description=Just a test for watchdogs etc
+
+[Service]
+ExecStart=/path/to/binary/sdnotify
+Type=notify
+NotifyAccess=main
+WatchdogSec=5s
+Restart=on-failure