How to Change the Default Port in Spring Boot

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Hello Friends!, We are going to learn how to change Spring Boot Application Port.By Default Spring Boot application runs on embedded Tomcat Server on port 8080

In this tutorial, we will cover common ways to change port number of embedded server.

you can check our other post on the Maven project, on how to create Spring Boot Application using the below ways.

Using Spring Initializr.

Application in STS.

Application with Eclipse and Maven manually

Using Property Files or YAML File

this is easiest and simple way to change Spring Boot default properties.

for server port we need to change server.port property value, let see how we can do that.

application.properties

create application.properties file under src/main/resources/ folder.

server.port=8181

now application will start with 8181 port.

application.yaml

create application.yaml file under src/main/resources/ folder.

server:
  port: 8282

now application will start with 8282 port.

If Both files used in the application , application.propertiesfile will get used. Both the file will get loaded by Spring Boot application if it’s placed under src/main/resources/

Using Command Line Arguments

when running application as jar, we can provide server.port argument while starting of Spring Boot application in two ways.

java -jar -Dserver.port=8383 springboot-first-application.jar

or

java -jar springboot-first-application.jar --server.port=8383

Programmatic Configuration

we can configure port programmatically in the following ways. as in SpringBootApplication main class or implement WebServerFactoryCustomizer.

@SpringBootApplication main class

while starting the application. we can provide port details to SpringApplication class as shown in the below code.

package com.gyanideveloper.springboot;

import java.util.Collections;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class App {

	public static void main(String[] args) {
		SpringApplication application = new SpringApplication(App.class);
		application.setDefaultProperties(Collections.singletonMap("server.port", "8484"));
		application.run(args);
	}

}

using WebServerFactoryCustomizer 

implement WebServerFactoryCustomizer  to configure port.

package com.gyanideveloper.springboot;

import org.springframework.boot.web.server.ConfigurableWebServerFactory;
import org.springframework.boot.web.server.WebServerFactoryCustomizer;
import org.springframework.stereotype.Component;

@Component
public class WebServerCustomizer implements WebServerFactoryCustomizer<ConfigurableWebServerFactory> {

	@Override
	public void customize(ConfigurableWebServerFactory factory) {
		factory.setPort(8585);
	}

}

This applies to Spring Boot 2.x

For Spring Boot 1.x

we can implement as follows.

@Configuration
public class ServletConfig {
    @Bean
    public EmbeddedServletContainerCustomizer containerCustomizer() {
        return (container -> {
            container.setPort(8585);
        });
    }
}

Order Of Evaluation By Spring Boot application

as we have used different way to configure server port , let see order in which evaluated by Spring Boot Application.

 the configurations priority is

  • Embedded server configuration or WebServerFactoryCustomizer configuration.
  • common line arguments
  • properties file
  • SpringBootApplication main class configuration

Use a Random Port

we can configure random port by setting server.port=0 , Spring scan for a free port (using OS natives to prevent clashes) .

server.port=0

Final Note

we have learn how to set server port in spring boot application.

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