Converting a Spring Boot Executable Jar to a Deployable War File

By default Spring Boot applications build an executable jar file. This is ideal for development and testing however when it’s time to deploy to a production container such as VMware tc Server there are a few simple steps which must be performed.

There are two options.

Option 1: Start with a Deployable War

If using the Spring Initializer to start the project choose the War option for Packaging

Packaging: War

and deploy to VMware tc Server for testing.

Option 2: Converting to Deployable War (Gradle)

If the project was already started with an executable Jar file there are just a few steps which need to be performed

1. Add the war plugin

   plugins {
       id 'org.springframework.boot' version '2.3.4.RELEASE'
       id 'io.spring.dependency-management' version '1.0.10.RELEASE'
       id 'java'
       id 'war' // Insert this line
   }
   

2. Change the embedded tomcat to provided

   dependencies {
       implementation 'org.springframework.boot:spring-boot-starter-web'
       providedRuntime 'org.springframework.boot:spring-boot-starter-tomcat' // Insert this line
       testImplementation('org.springframework.boot:spring-boot-starter-test') {
               exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
       }
   }
   

3. Add ServletInitializer

   package com.example.demo;
   
   import org.springframework.boot.builder.SpringApplicationBuilder;
   import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
   
   public class ServletInitializer extends SpringBootServletInitializer {
   
       @Override
       protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
               return application.sources(DemoApplication.class); // Replace DemoApplication with your main class
       }
   
   }
   

Option 2: Converting to Deployable War (Maven)

If the project was already started with an executable Jar file there are just a few steps which need to be performed

1. Add the war plugin

   <groupId>com.example</groupId>
   <artifactId>demo</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <packaging>war</packaging> // Change this from jar to war
   <name>demo</name>
   <description>Demo project for Spring Boot</description>
   

2. Change the embedded tomcat to provided

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

3. Add ServletInitializer

   package com.example.demo;
   
   import org.springframework.boot.builder.SpringApplicationBuilder;
   import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
   
   public class ServletInitializer extends SpringBootServletInitializer {
   
       @Override
       protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
               return application.sources(DemoApplication.class); // Replace DemoApplication with your main class
       }
   
   }