Conditional modules

In the previous sections, you’ve learned how to add modules by using the @AcrossApplication annotation. It is also possible to specify a module by defining it as a bean. When a module is defined as a bean, it will be added to the ApplicationContext, but since a module always implements the AcrossModule interface, it will also be picked up by the AcrossContext. By using this approach, Spring annotations can be used to define when exactly the module should be created. In the following examples, you’ll add DebugWebModule to the application once again, but instead of specifying the module by name, you’ll add it as a bean.

First off, you’ll add the module when starting the application with the dev profile.

If you haven’t read about application profiles yet, take a look at Application profiles.

Adding a module when the dev profile is present
@AcrossApplication( modules = { } )
public class DemoApplication
{
    ...

    @Bean (1)
    @Profile("dev") (2)
    public DebugWebModule debugWebModule(){
        return new DebugWebModule();  (3)
    }
}
1 We specify the module as a bean so that it can be picked up by the AcrossContext.
2 We specify the @Profile annotation so that it is only added when the dev profile is active.
3 We return an instance that will be bootstrapped as a module.

If we would now simply start up the application again, we would notice that neither DebugWebModule nor AcrossWebModule are bootstrapped into the application.

Starting the application without any profiles
...
INFO --- [  restartedMain] com.example.demo.DemoApplication         : No active profile set, falling back to default profiles: default (1)
...
INFO --- [ost-startStop-1] c.f.a.c.AcrossDynamicModulesConfigurer   : Adding package based APPLICATION module DemoApplicationModule, resources: demo, base package: com.example.demo.application
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : ---
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : AcrossContext: DemoApplication (AcrossContext-1)
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : Bootstrapping 2 modules in the following order: (2)
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : 1 - DemoApplicationModule [resources: demo]: class com.foreach.across.core.DynamicAcrossModule$DynamicApplicationModule
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : 2 - AcrossContextPostProcessorModule [resources: AcrossContextPostProcessorModule]: class com.foreach.across.core.AcrossContextConfigurationModule
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : ---
...
1 We started the application without any profile, so only the 'default' profile is present.
2 Neither DebugWebModule nor AcrossWebModule have been bootstrapped.

If we would then start up the application with the dev profile, these modules will be bootstrapped once again.

$ mvn spring-boot:run -Dspring-boot.run.profiles=dev

Starting the application with the dev profile
...
INFO --- [  restartedMain] com.example.demo.DemoApplication         : The following profiles are active: dev (1)
...
INFO --- [ost-startStop-1] c.f.a.c.AcrossDynamicModulesConfigurer   : Adding package based APPLICATION module DemoApplicationModule, resources: demo, base package: com.example.demo.application
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : ---
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : AcrossContext: DemoApplication (AcrossContext-1)
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : Bootstrapping 4 modules in the following order: (2)
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : 1 - AcrossWebModule [resources: ]: class com.foreach.across.modules.web.AcrossWebModule
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : 2 - DebugWebModule [resources: debugweb]: class com.foreach.across.modules.debugweb.DebugWebModule
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : 3 - DemoApplicationModule [resources: demo]: class com.foreach.across.core.DynamicAcrossModule$DynamicApplicationModule
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : 4 - AcrossContextPostProcessorModule [resources: AcrossContextPostProcessorModule]: class com.foreach.across.core.AcrossContextConfigurationModule
INFO --- [ost-startStop-1] c.f.a.c.c.bootstrap.AcrossBootstrapper   : ---
...
1 We have started the application with the dev profile.
2 DebugWebModule and AcrossWebModule are bootstrapped as well.
Adding a module based on configured properties
@AcrossApplication( modules = { } )
public class DemoApplication
{
    ...

    @Bean (1)
    @ConditionalOnProperty("dev") (2)
    public DebugWebModule debugWebModule(){
        return new DebugWebModule();  (3)
    }
}
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