Timeout for Dropwizard's health checks?

Question

I have two sql database connections for which health checks are automatically added by dropwizard. But when the application loses connection to one of them, the /healthcheck endpoint takes indefinitely long to respond, where I would want it to timeout after a few seconds.

I've already set the maxWaitForConnection setting, and I've also experimented with the various checkConnectionOn.. settings, but nothing helped.

UPDATE: The health check correctly fails if the server actively refuses the connection, but it hangs indefinitely if it's not the case, for instance, a network issue.

Is it possible to have sql health checks timeout at a specified time value whatever the problem is?

Answer 1

If the JDBC timeout settings aren't working you could always just wrap the DB check in a Future and limit how long it can run:

protected Result check() throws Exception {
  ExecutorService executor = Executors.newSingleThreadExecutor();
  Future<Void> future = executor.submit(new DbConnectionChecker());

  try {
    future.get(SECONDS_THRESHOLD, TimeUnit.SECONDS);
  } catch (TimeoutException e) {
    return Result.unhealthy("DB timed out");
  }
  executor.shutdownNow();
  return Result.healthy();
}

Where DbConnectionChecker is something like:

static class DbConnectionChecker implements Callable<Void> {
  public Void call() throws Exception {
    // Check your DB connection as you normally would
  }
}

Would be nice to figure out why the JDBC connection settings aren't working as expected, though.