Spring Boot调用 Shell 脚本实现看门狗功能

需要实现看门狗功能，定时检测另外一个程序是否在运行，使用 crontab 仅可以实现检测程序是否正在运行，无法做到扩展，如：手动重启、程序升级(如果只需要实现自动升级功能可以使用 inotify)等功能；最后决定使用 spring boot 调用 shell 脚本来实现

一、脚本

1.1 启动脚本

#!/bin/bash

ps -ef | grep "demo-app-0.0.1-snapshot.jar" | grep -v "grep"

if [ "$?" -eq 0 ]
then

# sleep
echo $(date "+%y-%m-%d %h:%m:%s") "process already started!"

else

nohup java -jar -server /project/watchdog/demo-app-0.0.1-snapshot.jar &
echo $(date "+%y-%m-%d %h:%m:%s") "process has been started!"

fi

1.2 重启脚本

#!/bin/bash

pid=`ps -ef | grep "demo-app-0.0.1-snapshot.jar" | grep -v "grep" | awk '{print $2}'`

for id in $pid
do
 kill -9 $id
 echo "killed $id"
done

nohup java -jar -server /project/watchdog/demo-app-0.0.1-snapshot.jar &
echo $(date "+%y-%m-%d %h:%m:%s") "process has been restarted!"

二、功能实现

将脚本放置在程序的资源目录下，每次程序启动时将脚本读取到指定位置，然后再通过定时任务执行脚本

配置内容：

shell:
 directory: /project/watchdog
 startupfilename: startup.sh
 restartfilename: restart.sh
@configuration
@configurationproperties(prefix = "shell")
public class shellproperties {

 private string directory;
 private string startupfilename;
 private string restartfilename;

 /* getter & setter */

 public string getfullname(string filename) {
 return directory + file.separator + filename;
 }
}

2.1 启动时将脚本读取到指定位置

@component
public class initrunner implements commandlinerunner {

 @autowired
 private shellproperties shellproperties;

 @autowired
 resourceloader resourceloader;

 @override
 public void run(string... args) throws exception {
 generatefile(shellproperties.getstartupfilename());
 generatefile(shellproperties.getrestartfilename());
 }

 private void generatefile(string filename) throws ioexception {

 string filefullname = shellproperties.getfullname(filename);
 file file = new file(filefullname);
 if(file.exists()) {
 return;
 }

 // 如果文件已存在，filewriter 会先删除再新建
 filewriter filewriter = new filewriter(filefullname);

 resource resource = resourceloader.getresource("classpath:" + filename);
 inputstream inputstream = resource.getinputstream();
 inputstreamreader inputstreamreader = new inputstreamreader(inputstream);
 bufferedreader bufferedreader = new bufferedreader(inputstreamreader);

 string data;
 while ((data = bufferedreader.readline()) != null) {
 filewriter.write(data + "\n");
 }

 bufferedreader.close();
 inputstreamreader.close();
 inputstream.close();

 filewriter.close();

 // 设置权限，否则会报 permission denied
 file.setreadable(true);
 file.setwritable(true);
 file.setexecutable(true);
 }
}

2.2 定时任务定时任务执行脚本

@component
public class shelltask {

 private static final logger logger = loggerfactory.getlogger(shelltask.class);

 @autowired
 private shellproperties shellproperties;

 @scheduled(cron = "0/10 * * * * ? ")
 public void start() throws ioexception {
 executeshell(shellproperties.getstartupfilename());
 }

 private void executeshell(string filename) throws ioexception {

 string filefullname = shellproperties.getfullname(filename);
 file file = new file(filefullname);
 if(!file.exists()) {
 logger.error("file {} not existed!", filefullname);
 return;
 }

 processbuilder processbuilder = new processbuilder(filefullname);
 processbuilder.directory(new file(shellproperties.getdirectory()));

 process process = processbuilder.start();

// string input;
// bufferedreader stdinput = new bufferedreader(new inputstreamreader(process.getinputstream()));
// bufferedreader stderror = new bufferedreader(new inputstreamreader(process.geterrorstream()));
// while ((input = stdinput.readline()) != null) {
// logger.info(input);
// }
// while ((input = stderror.readline()) != null) {
// logger.error(input);
// }

 int runningstatus = 0;
 try {
 runningstatus = process.waitfor();
 } catch (interruptedexception e) {
 logger.error("shell", e);
 }

 if(runningstatus != 0) {
 logger.error("failed.");
 }else {
 logger.info("success.");
 }
 }
}

2.3 扩展

本例只实现了定时检测程序是否运行，如果没有运行则启动程序；如有需要可以添加接口，调用接口重启程序；或者添加定时任务定时检测程序是否有更新，如果有更新则下载新的 jar 包然后重启程序

看门狗程序自己可以使用 crontab 定时检测是否正在运行，模仿上面的启动脚本编写看门狗的启动脚本，然后添加定时任务：

crontab -e
*/10 * * * * /project/watchdog/watchdog.sh
sudo systemctl reload crond.service

完整代码：github

参考：

总结

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