How to shutdown dropwizard application?

问题

I am trying to come up with a microservice using dropwizard. The documentation tells how to start the application, but says nothing about terminating it gracefully. Fir example, apache tomcat has both startup and shutdown scripts.

So does anyone know how to terminate a dropwizard application other than pressing Ctrl+C of kill ?

回答1:

Dropwizard Jetty has shutdown hooks. So kill -SIGINT <pid> works out really well.

回答2:

Inspired by praveenag's answer, I dug into Jetty's code.

If you start DropWizard providing:

-DSTOP.PORT=xxxx -DSTOP.KEY=my_secret_key

as Java options,

It tells Jetty to listen on that port for a stop request.

You can then write to that socket to tell Jetty to shutdown. I did this from R like this:

socket = make.socket("localhost", 8082)
write.socket(socket, "my_secret_key\r\n")
write.socket(socket, "stop\r\n")
close.socket(socket)

I guess you can do the same from any other language.

回答3:

The other answers here are great, but if you want to go a bit further up the stack and easily add custom logging / security / arbitrarily complex shutdown logic, then adding a shutdown hook via a dropwizard admin Task is a nice pattern.

Create a shutdown Task with any logic you like

import io.dropwizard.servlets.tasks.Task;

public class ShutdownTask extends Task {

  public ShutdownTask() {
    super("shutdown"); // the task name, used in the endpoint to execute it 
  }

  public void execute(
    ImmutableMultimap<String, String> immutableMultimap,
    PrintWriter printWriter
  ) throws Exception {
    // kill the process asynchronously with some nominal delay
    // to allow the task http response to be sent
    new Timer().schedule(new TimerTask() {
      public void run() {
        // any custom logging / logic here prior to shutdown
        System.exit(0);
      }
    }, 5000);
  }
}

environment.admin().addTask(new ShutdownTask());

And then execute it via a POST to the following endpoint on the admin port

http://localhost:<ADMIN PORT>/tasks/shutdown

回答4:

I am assuming this is not a question for your development environment but for your deployments. The answer depends on your deployment strategy. In the past we have handled deployments where the drop wizard application is bundled as a java process that can be started and the pid being recorded and forcefully kill the process. Or bundle the java process in an upstart/init script to gracefully start and shutdown the system.

On the other hand when you start a dropwizard application what it eventually does is start a jetty server. http://eureka.ykyuen.info/2010/07/26/jetty-stop-a-jetty-server-by-command. This can maybe shed some light on how you can pass the stop port as arguments when you start the dropwizard application.

回答5:

In Java:

// In case vm shutdown
Runtime.getRuntime().addShutdownHook(new Thread() {
    @Override
    public void run()
    {
        // what should be closed if forced shudown
        // ....

        LOG.info(String.format("--- End of ShutDownHook (%s) ---", "APPLICATION_NAME"));
    }
});

Build your own strategy, how to shutdown your app.

来源：https://stackoverflow.com/questions/25812816/how-to-shutdown-dropwizard-application

标签

java

dropwizard

microservices