Shutown Spring when DB is lost

Question

Use case

Our spring-boot-backend (v 2.3.1) using a postgres-database with HikariCP as connection pool.
The application is online and a admin accidentally kills the database.

Expected behavior

Spring notice that the connection to DB was lost. The application will gracefully shutdown.

Actual behavior

Spring is still running. All methods, which needs the db, ending up in exceptions.
To recover a complete good state, we need manually to restart spring.

Notes
We have a lot of async workers and they cannot recover correctly, when the database is going back online.
And docker/kubernetes will notice when the application shutdown and can automatically restart it.

Question

How can I reach the expected behavior?
Sadly I found nothing similar in the web.

Answer 1

With the hints from @Zubair I build a new small solution.
Iam using the Spring-Actuator-package, because they have some ready classes for this use-case.

All what I need was a HealthIndicator-Bean, like this

@Bean
public HealthIndicator dataSourceHealthIndicator(final DataSource dataSource) {
  return new DataSourceHealthIndicator(dataSource, "SELECT 1;");
}

and scheduled watcher (because HikariCP nor the HealthIndicators has any events).

@Scheduled(fixedRate = 10000L)
public void checkDBHealth() {
  final Status status = this.dataSourceHealthIndicator.health().getStatus();
  if (!Status.UP.equals(status)) {
    log.error("DATABASE IS OFFLINE! SHUTTING DOWN!");
    System.exit(1);
  }
}

I hope that will be useful for others.

Edit

I had to change the config of HikariCP. Otherwise the health-checker waiting almost endless for database-connection.

@Bean
public DataSource dataSource() {
  final HikariConfig config = new HikariConfig();
  // default settings with user, password, jdbc, ...
  config.setInitializationFailTimeout(1000);
  config.setConnectionTimeout(1000);
  config.setValidationTimeout(1000);

  return new HikariDataSource(config);
}