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：java去调用并执行shell脚本以及问题总结

总结

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