CODEWITHSUNDEEP
javadropwizardshutdown-hook
heaphach
heaphach

Reputation: 1492

Dropwizard Shutdown Hook

The problem is, that I stop Dropwizard application (via ctrl + c) and I have inserted a Shutdown Hook in main class to do some stuff before shutdown. But now ServerConnector for the application is closed before I can do what I want to do.

There is a polling service (polls one of my resources) and I need to tell them, that application will go down soon to prevent some problems. I need at least 15 seconds before ressource goes down.

Some idea how to solve this problem?

Upvotes: 7

Views: 7383

Answers (2)

Natan
Natan

Reputation: 2858

Add a Dropwizard Task that will change the state of a static field (or however you want to pass the data) which your polling resource will be using to respond.

public class ShutdownTask extends Task {
    private int timeoutSeconds;

    public ShutdownTask (int timeoutSeconds) {
        super("shutdown");
        this.timeoutSeconds = timeoutSeconds;
    }

      @Override
    public void execute(ImmutableMultimap<String, String> parameters, PrintWriter output) throws Exception {
        // you probably can take the timeout parameter from the request via 'parameters' instead of the constructor.
        PollingResource.shuttingDownIn = timeoutSeconds;
    }
}


environment.admin().addTask(new ShutdownTask(15));

Then write a bash script which will curl to task

curl -X POST http://dw.example.com:8081/tasks/shutdown

And:

  • This is probably not recommended (people don't like System.exit(0)) but you can add the following to execute method:

Thread.sleep(timeoutSeconds * 1000); System.exit(0)

  • Or do the waiting and kill the dropwizard app in the bash script.

kill -SIGINT <pid>

Upvotes: 6

scanning
scanning

Reputation: 111

You can use a lifecycle hook to manage certain resources. 

public class ManagedObject implements Managed {

    private final Object obj;

    public ManagedObject(Object obj) {
        this.obj = obj;
    }

    @Override
    public void start() throws Exception {
        // Do something to start the object
    }

    @Override
    public void stop() throws Exception {
        // Do something to stop the object
    }
}

Then register on the environment

ManagedObject myManagedObject = new ManagedObject(obj);
environment.lifecycle().manage(myManagedObject);

Upvotes: 9

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