Different Ways of Running Spring Boot Application

In this article, we will discuss different ways of running the Spring Boot application.

Spring boot offers several ways of running Spring boot applications.

Five ways we can run Spring Boot Application

1. Running from an IDE
2. Running as a Packaged Application
3. Using the Maven Plugin
4. Using External Tomcat
5. Using the Gradle Plugin

1. Running from an IDE

You can run a Spring Boot application from your IDE as a simple Java application (Application.java or Main class).

2. Running as a Packaged Application

If you use the Spring Boot Maven or Gradle plugins to create an executable jar, you can run your application using java -jar. For example, change directory to the current project directory and run following command in cmd.

$ java -jar target/myapplication-0.0.1-SNAPSHOT.jar

It is also possible to run a packaged application with remote debugging support enabled. Doing so lets you attach a debugger to your packaged application, as shown in the following example:

$ java -Xdebug -Xrunjdwp:server=y,transport=dt_socket,address=8000,suspend=n \
       -jar target/myapplication-0.0.1-SNAPSHOT.jar

3. Using the Maven Plugin

The Spring Boot Maven plugin includes a run goal that can be used to quickly compile and run your application. Applications run in an exploded form, as they do in your IDE. The following example shows a typical Maven command to run a Spring Boot application:

$ mvn spring-boot:run

We can also use the MAVEN_OPTS operating system environment variable, as shown in the following example:

$ export MAVEN_OPTS=-Xmx1024m

4. Using External Tomcat

We can also deploy Spring Boot web application WAR file to the external Tomcat servlet container. There are three steps we can follow to create a war file and deploy in external Tomcat servlet container.

Step 1: Change the packaging type.

<packaging>war</packaging>

Step 2. Add spring-boot-starter-tomcat as the provided scope

  <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-tomcat</artifactId>
      <scope>provided</scope>
  </dependency>

Step 3: Spring Boot Application or Main class extends SpringBootServletInitializer

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;

@SpringBootApplication
public class Application extends SpringBootServletInitializer{

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
    }
 
    public static void main(String[] args) {
         SpringApplication.run(Application.class, args);
    }
}

There is a separate article to know more how to deploy Spring boot WAR file to external tomcat on

Spring Boot Deploy WAR file to External Tomcat

5. Using the Gradle Plugin

The Spring Boot Gradle plugin also includes a bootRun task that can be used to run your application in an exploded form. The bootRun task is added whenever you apply the org.springframework.boot and java plugins and is shown in the following example:

$ gradle bootRun

You might also want to use the JAVA_OPTS operating system environment variable, as shown in the following example:

$ export JAVA_OPTS=-Xmx1024m

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