How to shutdown a Spring Boot Application in a cor

Question

In the Spring Boot Document, they said that 'Each SpringApplication will register a shutdown hook with the JVM to ensure that the ApplicationContext is closed gracefully on exit.'

When I click ctrl+c on the shell command, the application can be shutdown gracefully. If I run the application in a production machine, I have to use the command java -jar ProApplicaton.jar. But I can't close the shell terminal, otherwise it will close the process.

If I run command like nohup java -jar ProApplicaton.jar &, I can't use ctrl+c to shutdown it gracefully.

What is the correct way to start and stop a Spring Boot Application in the production environment?

Answer 1

If you are in a linux environment all you have to do is to create a symlink to your .jar file from inside /etc/init.d/

sudo ln -s /path/to/your/myboot-app.jar /etc/init.d/myboot-app

Then you can start the application like any other service

sudo /etc/init.d/myboot-app start

To close the application

sudo /etc/init.d/myboot-app stop

This way, application will not terminate when you exit the terminal. And application will shutdown gracefully with stop command.

Answer 2

If you are using the actuator module, you can shutdown the application via JMX or HTTP if the endpoint is enabled (add endpoints.shutdown.enabled=true to your application.properties file).

/shutdown - Allows the application to be gracefully shutdown (not enabled by default).

Depending on how an endpoint is exposed, the sensitive parameter may be used as a security hint. For example, sensitive endpoints will require a username/password when they are accessed over HTTP (or simply disabled if web security is not enabled).

From the Spring boot documentation

Answer 3

SpringApplication implicitly registers a shutdown hook with the JVM to ensure that ApplicationContext is closed gracefully on exit. That will also call all bean methods annotated with @PreDestroy. That means we don't have to explicitly use the registerShutdownHook() method of a ConfigurableApplicationContext in a boot application, like we have to do in spring core application.

@SpringBootConfiguration
public class ExampleMain {
    @Bean
    MyBean myBean() {
        return new MyBean();
    }

    public static void main(String[] args) {
        ApplicationContext context = SpringApplication.run(ExampleMain.class, args);
        MyBean myBean = context.getBean(MyBean.class);
        myBean.doSomething();

        //no need to call context.registerShutdownHook();
    }

    private static class MyBean {

        @PostConstruct
        public void init() {
            System.out.println("init");
        }

        public void doSomething() {
            System.out.println("in doSomething()");
        }

        @PreDestroy
        public void destroy() {
            System.out.println("destroy");
        }
    }
}

Answer 4

Here is another option that does not require you to change the code or exposing a shut-down endpoint. Create the following scripts and use them to start and stop your app.

start.sh

#!/bin/bash
java -jar myapp.jar & echo $! > ./pid.file &

Starts your app and saves the process id in a file

stop.sh

#!/bin/bash
kill $(cat ./pid.file)

Stops your app using the saved process id

start_silent.sh

#!/bin/bash
nohup ./start.sh > foo.out 2> foo.err < /dev/null &

If you need to start the app using ssh from a remote machine or a CI pipeline then use this script instead to start your app. Using start.sh directly can leave the shell to hang.

After eg. re/deploying your app you can restart it using:

sshpass -p password ssh -oStrictHostKeyChecking=no [e-mail] 'cd /home/user/pathToApp; ./stop.sh; ./silent_start.sh'

Answer 5

They are many ways to shutdown a spring application. One is to call close() on the ApplicationContext:

ApplicationContext ctx =
    SpringApplication.run(HelloWorldApplication.class, args);
// ...
ctx.close()

Your question suggest you want to close your application by doing Ctrl+C, that is frequently used to terminate a command. In this case...

Use endpoints.shutdown.enabled=true is not the best recipe. It means you expose an end-point to terminate your application. So, depending on your use case and your environment, you will have to secure it...

Ctrl+C should work very well in your case. I assume your issue is caused by the ampersand (&) More explanation:

A Spring Application Context may have register a shutdown hook with the JVM runtime. See ApplicationContext documentation.

I don't know if Spring Boot configure this hook automatically as you said. I assume it is.

On Ctrl+C, your shell sends an INT signal to the foreground application. It means "please interrupt your execution". The application can trap this signal and do cleanup before its termination (the hook registered by Spring), or simply ignore it (bad).

nohup is command that execute the following program with a trap to ignore the HUP signal. HUP is used to terminate program when you hang up (close your ssh connexion for example). Moreover it redirects outputs to avoid that your program blocks on a vanished TTY. nohupdoes NOT ignore INT signal. So it does NOT prevent Ctrl+C to work.

I assume your issue is caused by the ampersand (&), not by nohup. Ctrl+C sends a signal to the foreground processes. The ampersand causes your application to be run in background. One solution: do

kill -INT pid

Use kill -9 or kill -KILL is bad because the application (here the JVM) cannot trap it to terminate gracefully.

Another solution is to bring back your application in foreground. Then Ctrl+C will work. Have a look on Bash Job control, more precisely on fg.

Answer 6

All of the answers seem to be missing the fact that you may need to complete some portion of work in coordinated fashion during graceful shutdown (for example, in an enterprise application).

@PreDestroy allows you to execute shutdown code in the individual beans. Something more sophisticated would look like this:

@Component
public class ApplicationShutdown implements ApplicationListener<ContextClosedEvent> {
     @Autowired ... //various components and services

     @Override
     public void onApplicationEvent(ContextClosedEvent event) {
         service1.changeHeartBeatMessage(); // allows loadbalancers & clusters to prepare for the impending shutdown
         service2.deregisterQueueListeners();
         service3.finishProcessingTasksAtHand();
         service2.reportFailedTasks();
         service4.gracefullyShutdownNativeSystemProcessesThatMayHaveBeenLaunched(); 
         service1.eventLogGracefulShutdownComplete();
     }
}