CODEWITHSUNDEEP
javaspringspring-boot
Neymar
Neymar

Reputation: 41

How can I shutdown / not start a spring app if a flag was not provided?

I inject a flag using @Value("${FOO}") and I don't want my spring app start at all if it wasn't provided (i.e., FOO is a mandatory flag).

Here's my main class:

@SpringBootApplication
public class Application {
  public static void main(String[] args) {
    SpringApplication.run(Application.class, args);
  }
}

and I inject FOO into one of the services.

How can I do it?

Upvotes: 1

Views: 322

Answers (3)

user12047085
user12047085

Reputation: 162

SpringBoot runners can you used for doing this before the application starts up. you can find examples here https://www.tutorialspoint.com/spring_boot/spring_boot_runners.htm

Upvotes: 0

Kirill Simonov
Kirill Simonov

Reputation: 8491

Resolving of properties placeholders is controlled by PlaceholderConfigurerSupport. And by default it should throw an exception if it was unable to resolve a placeholder:

If a configurer cannot resolve a placeholder, a BeanDefinitionStoreException will be thrown.

However, when I tried to use a @Value with a property that didn't exist, it threw an exception, but it didn't stop the JVM.

What you can do to force it to stop is to implement InitializingBean and check the property in the afterPropertiesSet() method:

@Service
public class YourService implements InitializingBean {

    @Value("${foo:#{null}}") // set the default value to null
    private String foo;

    public void afterPropertiesSet() {
        if (foo == null) {
            throw new IllegalArgumentException("foo flag must be provided");
        }
    }
}

Upvotes: 1

Sujay Mohan
Sujay Mohan

Reputation: 952

If you want to inject Foo you need to start your application. This may not be the proper way but this will work. What you can do is to create a bean like this. In the bean you can add your own condition to shutdown the app. This will prevent the start of the app while the bean gets created. 

@SpringBootApplication
public class SampleApplication {

    @Value("${foo}")
    private String foo;

    @Bean
    public String preventStart() {
        if("no".equals(foo) ) {
            System.exit(0);
        }
        return "started";
    }

    public static void main(String[] args) {
        SpringApplication.run(SampleApplication.class, args);
    }
}

Upvotes: 0

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