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Basic Systemd sd_notify + watchdog usage
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| cmake_minimum_required(VERSION 2.8) | |
| project(sdnotify) | |
| add_executable(sdnotify sdnotify.cpp) | |
| target_link_libraries(sdnotify PUBLIC systemd) |
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| #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; | |
| } |
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| [Unit] | |
| Description=Just a test for watchdogs etc | |
| [Service] | |
| ExecStart=/path/to/binary/sdnotify | |
| Type=notify | |
| NotifyAccess=main | |
| WatchdogSec=5s | |
| Restart=on-failure |
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