By default, Spring boot applications start with embedded tomcat server start on default port 8080. We can change default server port to any other port, using any one of below technique.

1. Update default spring boot server port from application properties file

We can do parcels of brilliant things by basically making few passages in application properties record in any spring boot application. Changing server port is one of them.

1.1. application.properties

server.port=8081

1.1. application.yml

server:
  port : 8081

2. Update the spring boot server port number programmatically

EmbeddedServletContainerCustomizer interface is used to customize inbuilt tomcat configuration.

2.1. Spring boot2 – WebServerFactoryCustomizer interface

Alter default application server port in spring boot2 applications by implementing ConfigurableWebServerFactory interface.

@Component
public class AppContainerCustomizer 
			implements WebServerFactoryCustomizer< ConfigurableWebServerFactory > {
  
    @Override
    public void customize(ConfigurableWebServerFactory factory) {
        factory.setPort(8081);
    }
}

2.2. Spring boot 1.x – EmbeddedServletContainerCustomizer interface

Alter default server port in spring boot 1.x applications by implementing EmbeddedServletContainerCustomizer interface.

@Component
public class AppContainerCustomizer implements EmbeddedServletContainerCustomizer {

	@Override
	public void customize(ConfigurableEmbeddedServletContainer container) {

		container.setPort(8081);
	}
}

3. Update Spring boot default port number from command line

We will pass ‘server.port’ argument during application run command.

java -jar -Dserver.port=8081 spring-boot-demo.jar