在服务中调用sd_notify(0,"WATCHDOG = 1")

Question

我有一个系统服务.我想为此实施看门狗.它是这样的,

[Unit]
Description=Watchdog example service

[Service]
Type=notify
Environment=NOTIFY_SOCKET=/run/%p.sock
ExecStartPre=-/usr/bin/docker kill %p
ExecStartPre=-/usr/bin/docker rm %p
ExecStart=/usr/libexec/sdnotify-proxy /run/%p.sock /usr/bin/docker run \
    --env=NOTIFY_SOCKET=/run/%p.sock \
    --name %p pranav93/test_watchdogged python hello.py
ExecStop=/usr/bin/docker stop %p

Restart=on-success
WatchdogSec=30s
RestartSec=30s


[Install]
WantedBy=multi-user.target

根据文档,我要调用sd_notify("watchdog=1")指定间隔的每一半(在这种情况下是它15s).但我不知道如何在服务中调用该函数.帮助将受到高度赞赏.

Answer 1

我不得不安装systemd lib:

sudo apt-get install libsystemd-dev

并编译将程序传递给链接器:

gcc testWatchDogProcess.c -o testWatchDogProcess -lsystemd

我在@rameshrgtvl代码中进行了一些更改,使其直接运行,没有任何警告或错误.

#include <systemd/sd-daemon.h>
#include <fcntl.h>
#include <time.h>
/* This should be sent once you are done with your initialization */
/* Until you call this systemd will keep your service as activating status */
/* Once you called, systemd will change the status of ur service to active */

#define true  1

int main ()
{
        sd_notify (0, "READY=1");

        /* Way to get the WatchdogSec value from service file */
        char * env;
        int interval=0;
        int isRun = true;
        env = getenv("WATCHDOG_USEC");
        if (env)
        {
                interval = atoi(env)/(2*1000000);
        }
        /* Ping systsemd once you are done with Init */
        sd_notify (0, "WATCHDOG=1");

        /* Now go for periodic notification */
        while(isRun == true)
        {
                sleep(interval);
            /* Way to ping systemd */
                sd_notify (0, "WATCHDOG=1");
        }
        return 0;
}

Answer 2

sd_notify(0,"WATCHDOG=1") 是用于通知systemd您的进程运行正常的API。

正如Type=notify已经使用过的，sd_notify(0,"WATCHDOG=1")应该在不使用服务的应用程序中调用它，并且必须定期进行调用（在30秒之前，因为在服务文件中提到了WatchdogSec = 30s），这样systemd就可以得到其他通知，

systemd会将其视为失败的服务，因此systemd将终止您的服务并重新启动它。

Answer 3

样本服务文件

[Unit]
Description=Test watchdog Demo process
DefaultDependencies=false
Requires=basic.target

[Service]
Type=notify
WatchdogSec=10s
ExecStart=/usr/bin/TestWatchDogProcess
StartLimitInterval=5min
StartLimitBurst=5
StartLimitAction=reboot
Restart=always

testWatchDogProcess.c的示例代码:

#include "systemd/sd-daemon.h"
#include <fcntl.h>
#include <time.h>

/* This should be sent once you are done with your initialization */
/* Until you call this systemd will keep your service as activating status */
/* Once you called, systemd will change the status of ur service to active */

sd_notify (0, "READY=1");

/* Way to get the WatchdogSec value from service file */
env = getenv("WATCHDOG_USEC");
if(env != NULL)
int interval = atoi(env)/(2*1000000);

/* Ping systsemd once you are done with Init */
sd_notify (0, "WATCHDOG=1");

/* Now go for periodic notification */
while(isRun == true)
{
    sleep(interval);
    /* Way to ping systemd */
    sd_notify (0, "WATCHDOG=1");
}

    return 0;

}

注意:根据您的systemd版本,请注意在编译期间包含正确的标题和库.