Spring Boot without the web server

Question

if you want to run spring boot without a servlet container, but with one on the classpath (e.g. for tests), use the following, as described in the spring boot documentation:

@Configuration
@EnableAutoConfiguration
public class MyClass {
    public static void main(String[] args) throws JAXBException {
         SpringApplication app = new SpringApplication(MyClass.class);
         app.setWebEnvironment(false); //<<<<<<<<<
         ConfigurableApplicationContext ctx = app.run(args);
    }
}

also, I just stumbled across this property:

spring.main.web-environment=false

Spring Boot 2.x

• Application Properties

  spring.main.web-application-type=NONE 
  # REACTIVE, SERVLET
  

• or SpringApplicationBuilder

  @SpringBootApplication
  public class MyApplication {
  
      public static void main(String[] args) {
          new SpringApplicationBuilder(MyApplication.class)
              .web(WebApplicationType.NONE) // .REACTIVE, .SERVLET
              .run(args);
     }
  }
  

---

Where WebApplicationType:

• NONE - The application should not run as a web application and should not start an embedded web server.
• REACTIVE - The application should run as a reactive web application and should start an embedded reactive web server.
• SERVLET - The application should run as a servlet-based web application and should start an embedded servlet web server.

You can create something like this:

@SpringBootApplication
public class Application {
  public static void main(String[] args) {
    new SpringApplicationBuilder(Application.class).web(false).run(args);
  }
}

And

@Component
public class CommandLiner implements CommandLineRunner {

  @Override
  public void run(String... args) throws Exception {
    // Put your logic here
  }

}

The dependency is still there though but not used.

Spring boot will not include embedded tomcat if you don't have Tomcat dependencies on the classpath. You can view this fact yourself at the class EmbeddedServletContainerAutoConfiguration whose source you can find here.

The meat of the code is the use of the @ConditionalOnClass annotation on the class EmbeddedTomcat

---

Also, for more information check out this and this guide and this part of the documentation

Use this code.

SpringApplication application = new SpringApplication(DemoApplication.class);
application.setWebApplicationType(WebApplicationType.NONE);
application.run(args);