How to Package Spring Boot as a WAR and Deploy to an External Tomcat

Overview

Spring Boot normally runs with an embedded Tomcat, but many production environments use a separately managed Tomcat instance. This article walks through converting a Spring Boot application into a deployable WAR file and deploying it to an external Tomcat container.

Change Packaging to WAR

<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>

Remove Embedded Tomcat

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
  <!-- Remove embedded Tomcat plugin -->
  <exclusions>
    <exclusion>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-tomcat</artifactId>
    </exclusion>
  </exclusions>
</dependency>

Add servlet‑api Dependency

<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>javax.servlet-api</artifactId>
  <version>3.1.0</version>
  <scope>provided</scope>
</dependency>

Create Servlet Initializer

public class SpringBootStartApplication extends SpringBootServletInitializer {
    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
        // Point to the original Application class that contains the main method
        return builder.sources(Application.class);
    }
}

Build and Deploy

Run mvn clean package in the project root (where pom.xml resides). The build should finish with [INFO] BUILD SUCCESS and produce a .war file in the target directory.

Copy the generated WAR to Tomcat’s webapps directory and start Tomcat. Tomcat will automatically unpack and deploy the application.

Access the application via http://YOUR_IP:PORT/your‑project‑name. Optionally rename the WAR to ROOT.war to make it accessible at the root context ( http://YOUR_IP:PORT/).

Verification

The following screenshots show the successful deployment and access of the Spring Boot application on the external Tomcat server.