Spring Boot – how to build war?

Spring Boot – How to Build a WAR?

Spring Boot applications are typically packaged as executable JAR files, which include an embedded web server. However, there are scenarios where deploying a WAR (Web Application Archive) is necessary, such as when deploying to a traditional application server like Tomcat, JBoss, or WebSphere. Building a WAR file involves configuring your Spring Boot application to be deployable in these environments, which requires some adjustments to the project setup.

Solution: Building a WAR in Spring Boot

To build a WAR file in Spring Boot, you need to make several changes to your project configuration and code. Below are the steps and code examples to achieve this:

1. Modify the pom.xml or build.gradle

For Maven:

In your pom.xml, change the packaging type from jar to war:

<packaging>war</packaging>

Ensure you have the spring-boot-starter-tomcat dependency provided:

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

For Gradle:

In your build.gradle, apply the war plugin:

apply plugin: 'war'

Ensure the spring-boot-starter-tomcat dependency is provided:

dependencies {
    providedRuntime 'org.springframework.boot:spring-boot-starter-tomcat'
}

2. Extend SpringBootServletInitializer

Create a class that extends SpringBootServletInitializer and override the configure method:

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
class MySpringBootApplication : SpringBootServletInitializer() {
    override fun configure(application: SpringApplicationBuilder): SpringApplicationBuilder {
        return application.sources(MySpringBootApplication::class.java)
    }
}

fun main(args: Array<String>) {
    SpringApplication.run(MySpringBootApplication::class.java, *args)
}

3. Build the WAR

For Maven:

Run the following command to build the WAR file:

mvn clean package

For Gradle:

Run the following command to build the WAR file:

./gradlew clean build

Output

After building, you will find the WAR file in the target directory for Maven or build/libs for Gradle. This WAR file can be deployed to any compatible application server.

Advantages

• Compatibility: Allows deployment on traditional application servers.
• Flexibility: Supports environments where embedded servers are not suitable.

Disadvantages

• Complexity: Requires additional configuration compared to JAR packaging.
• Dependency Management: Must ensure all dependencies are correctly scoped.

Similar Topics

1. How to deploy a Spring Boot application to Tomcat?
2. Differences between JAR and WAR packaging in Spring Boot.
3. How to configure a Spring Boot application for a traditional server?
4. Steps to migrate a Spring Boot JAR to a WAR.
5. How to handle servlet configurations in a Spring Boot WAR?
6. Best practices for deploying Spring Boot applications in enterprise environments.
7. How to troubleshoot deployment issues in application servers?
8. Configuring Spring Boot for multi-environment deployments.
9. How to integrate Spring Boot with legacy systems?
10. Understanding the Spring Boot application lifecycle in a WAR deployment.