How to configure port for a Spring Boot application

Question

How do I configure the TCP/IP port listened on by a Spring Boot application, so it does not use the default port of 8080.

Answer 1

By default spring boot app start with embedded tomcat server start at default port 8080. spring provides you with following different customization you can choose one of them.

NOTE – you can use server.port=0 spring boot will find any unassigned http random port for us.

1) application.properties

server.port=2020

2) application.yml

server:  
     port : 2020

3) Change the server port programatically

3.1) By implementing WebServerFactoryCustomizer interface - Spring 2.x

@Component
public class MyTomcatWebServerCustomizer implements WebServerFactoryCustomizer {

    @Override
    public void customize(TomcatServletWebServerFactory factory) {
        // customize the factory here
        factory.setPort(2020);
    }
}

3.2) By Implementing EmbeddedServletContainerCustomizer interface - Spring 1.x

@Component
public class CustomizationBean implements EmbeddedServletContainerCustomizer {

    @Override
    public void customize(ConfigurableEmbeddedServletContainer container) {
        // customize here
        container.setPort(2020);
    }
}

4) By using command line option

 java -jar spring-boot-app.jar -Dserver.port=2020