Spring Boot – Deploy WAR file to Tomcat

In this article, we will show you how to deploy a Spring Boot WAR file to the Tomcat servlet container.

For Spring Boot WAR deployment, you need to do three steps:

1. Extends SpringBootServletInitializer
2. Marked the embedded servlet container as provided.
3. Update packaging to war

Tested

1. Spring Boot 1.4.2.RELEASE
2. Tomcat 8.5.9
3. Maven 3

1. Extends SpringBootServletInitializer

Make the existing @SpringBootApplication class extends SpringBootServletInitializer

1.1 Classic Spring Boot JAR deployment. (Update this file to support WAR deployment)

import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringBootWebApplication {

    public static void main(String[] args) throws Exception {
        SpringApplication.run(SpringBootWebApplication.class, args);
    }

}

1.2 Spring Boot WAR deployment.

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

@SpringBootApplication
public class SpringBootWebApplication extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(SpringBootWebApplication.class);
    }

    public static void main(String[] args) throws Exception {
        SpringApplication.run(SpringBootWebApplication.class, args);
    }

}

/*@SpringBootApplication
public class SpringBootWebApplication {

    public static void main(String[] args) throws Exception {
        SpringApplication.run(SpringBootWebApplication.class, args);
    }

}*/

If you create a extra SpringBootWebApplication class for deployment, make sure tell Spring Boot which main class to start :

  <properties>
        <start-class>com.mkyong.NewSpringBootWebApplicationForWAR</start-class>
  </properties>

Read this – Spring Boot – Which main class to start

2. Marked the embedded servlet container as provided

<dependencies>

	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-thymeleaf</artifactId>
	</dependency>

	<!-- marked the embedded servlet container as provided -->
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-tomcat</artifactId>
		<scope>provided</scope>
	</dependency>

</dependencies>

3. Update packaging to war

  <packaging>war</packaging>

Done, mvn package and copy the $project/target/xxx.war to Tomcat for deployment.

4. Full example – Spring Boot WAR + Tomcat Deployment

4.1 Take this Spring Boot Thymeleaf example, update it and deploy to Tomcat manually.

4.2 Update the existing SpringBootWebApplication and make it extends the SpringBootServletInitializer

package com.mkyong;

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

@SpringBootApplication
public class SpringBootWebApplication extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(SpringBootWebApplication.class);
    }

    public static void main(String[] args) throws Exception {
        SpringApplication.run(SpringBootWebApplication.class, args);
    }

}

4.3 Update the packaging to war and mark the spring-boot-starter-tomcat as provided.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
	http://maven.apache.org/xsd/maven-4.0.0.xsd">
	
    <modelVersion>4.0.0</modelVersion>

    <artifactId>spring-boot-web-thymeleaf</artifactId>
    <packaging>war</packaging>
    <name>Spring Boot Web Thymeleaf Example</name>
    <description>Spring Boot Web Thymeleaf Example</description>
    <url>https://www.mkyong.com</url>
    <version>1.0</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.2.RELEASE</version>
    </parent>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

        <!-- marked the embedded servlet container as provided -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>

        <!-- hot swapping, disable cache for template, enable live reload -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
        </dependency>

        <!-- Optional, for bootstrap -->
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>bootstrap</artifactId>
            <version>3.3.7</version>
        </dependency>

    </dependencies>
    <build>
        <plugins>
            <!-- Package as an executable jar/war -->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

4.4 This is optional, update the contextPath to /mkyong for demonstration later. Done. Ready for WAR deployment.

welcome.message: Hello Mkyong

server.contextPath=/mkyong

4.5 Get Tomcat and Deploy WAR file.

# Get Tomcat 8.5.9
spring-boot-project$ curl -O  http://www-us.apache.org/dist/tomcat/tomcat-8/v8.5.9/bin/apache-tomcat-8.5.9.tar.gz
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 9112k  100 9112k    0     0   799k      0  0:00:11  0:00:11 --:--:-- 1348k

# Extract it
$ tar -xvzf apache-tomcat-8.5.9.tar.gz 

# Maven clean and package everything into a WAR file.
$ mvn clean package

# Copy WAR to Tomcat/webapp, renamed to mkyong.war
# By default, Tomcat take the war file name as the context path
$ cp target/spring-boot-web-thymeleaf-1.0.war apache-tomcat-8.5.9/webapps/mkyong.war

# Start Tomcat
$ ./apache-tomcat-8.5.9/bin/startup.sh 
Using CATALINA_BASE:   /Users/mkyong/projects/spring-boot-web-thymeleaf/apache-tomcat-8.5.9
Using CATALINA_HOME:   /Users/mkyong/projects/spring-boot-web-thymeleaf/apache-tomcat-8.5.9
Using CATALINA_TMPDIR: /Users/mkyong/projects/spring-boot-web-thymeleaf/apache-tomcat-8.5.9/temp
Using JRE_HOME:        /Library/Java/JavaVirtualMachines/jdk1.8.0_74.jdk/Contents/Home
Using CLASSPATH:       /Users/mkyong/projects/spring-boot-web-thymeleaf/apache-tomcat-8.5.9/bin/bootstrap.jar:
/Users/mkyong/projects/spring-boot-web-thymeleaf/apache-tomcat-8.5.9/bin/tomcat-juli.jar
Tomcat started.

4.6 Access http://localhost:8080/mkyong/

4.7 Done. Shut down Tomcat.

$ ./apache-tomcat-8.5.9/bin/shutdown.sh 

Download Source Code

References

1. Spring Boot – Traditional deployment
2. Spring Boot Hello World Example – Thymeleaf
3. How to Install Apache Tomcat 8 On Debian