How to Change the Default Port in Spring Boot

author : Sai K

By default, Spring Boot applications run on port 8080. However, you may need to change this port for various

reasons, such as avoiding conflicts with other applications. This tutorial will guide you through different methods

to change the default port in a Spring Boot application.

Method 1: Using application.properties

The simplest way to change the default port is by setting the server.port property in the application.properties file.

Step 1: Set Up a Spring Boot Project

Use Spring Initializr to create a new project with the following dependencies:

  • Spring Web

    • Download and unzip the project, then open it in your IDE.

    Step 2: Configure application.properties

    Set up the application properties to change the default port. This file is located in the src/main/resources

    directory. 

    
                        # src/main/resources/application.properties

                        # Server port configuration
                        server.port=9090

    Explanation:

    • server.port=9090: Changes the server port from the default 8080 to 9090.

    Method 2: Using application.yml

    You can also change the default port using the application.yml file.

    Step 1: Set Up a Spring Boot Project

    Use Spring Initializr to create a new project with the following dependencies:

  • Spring Web

    • Download and unzip the project, then open it in your IDE.

    Step 2: Configure application.yml

    Set up the application YAML configuration to change the default port. This file is located in the

    src/main/resources directory.

    
# src/main/resources/application.yml
server:
  port: 9090

    Explanation:

    server.port: 9090: Changes the server port from the default 8080 to 9090.

    Method 3: Using Command Line Arguments

    You can override the default port by passing a command line argument when starting the application.

    Step 1: Run the Application with a Command Line Argument

    Use the following command to run the Spring Boot application with a different port:

    ./mvnw spring-boot:run -Dspring-boot.run.arguments=--server.port=9090

    Explanation:

    • -Dspring-boot.run.arguments=--server.port=9090: Specifies the port as a command line argument.

    Method 4: Programmatically Setting the Port

    You can programmatically set the port by configuring a ConfigurableServletWebServerFactory bean.

    Step 1: Create a Configuration Class.

    Create a new configuration class to set the port programmatically.

    
    package com.example.demo.config;

import org.springframework.boot.web.server.ConfigurableWebServerFactory;
import org.springframework.boot.web.server.WebServerFactoryCustomizer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class WebServerConfig {

    @Bean
    public WebServerFactoryCustomizer webServerFactoryCustomizer() {
        return factory -> factory.setPort(9090);
    }
}

    Explanation:

    • WebServerFactoryCustomizer: Customizes the web server factory to set the port.

    • factory.setPort(9090): Sets the server port to 9090.

    Method 5: Using Environment Variables

    You can use environment variables to set the port.

    Step 1: Set the Environment Variable

    Set the SERVER_PORT environment variable before running the application.

    For Unix-based systems (Linux, macOS):

    
    export SERVER_PORT=9090
    ./mvnw spring-boot:run

    For Windows:

    
set SERVER_PORT=9090
./mvnw spring-boot:run

    Explanation:

    SERVER_PORT=9090: Sets the environment variable for the server port to 9090.

    Conclusion

    In this tutorial, you have learned different methods to change the default port in a Spring Boot application. The

    methods include:


    • Using application.properties

    • Using application.yml

    • Using command line arguments

    • Programmatically setting the port

    • Using environment variables

    By following these steps, you can effectively change the default port of your Spring Boot application to suit your

    needs.