o7planning

Deploy Spring Boot Application on Tomcat Server

1- Objective of post

In this post, I will guide you for implementing a Spring Boot application on Tomcat Server. One of the characteristics of the Tomcat is compact. The capacity of theTomcat is only about 10MB, and an open source Java Web Server.
Ensure that you have installed the Tomcat successfully. If not, you can refer to Tomcat installations as in the following post:
In fact, the Spring Boot application can be packaged into an Executable JAR file. With this file you can run the application directly without needing to deploy it on any Web Server. The Executable JAR file may not be compatible with all Web servers, therefore, you want to deploy it on a particular Web server, you need to package the Spring Boot application into a WAR file.

2- Edit code

I have a Spring Boot project here, developed by Eclipse IDE. When creating the Spring Boot project, you have 2 choices to pack this project such as WAR or JAR.
When you create the Spring Boot project with the "Packaging = War" option, Eclipse will create 2 classes such as "AbcApplication & ServletInitializer" for you. The WAR files are suitable for being deployed on  Web Servers.
While, if you create a Spring Boot project with the "Packaging = Jar" choice, only one AbcApplication class will be created. When the Spring Boot application is packed into the JAR file, it can be independently executabe without being deployed on any Web Server. But the  JAR file is not suitable to be deployed on Web Servers.

WAR File.

If you have an available Spring Boot, you need to correct packaging method into WAR:
On the Eclipse, open the pom.xml file, and change packaging method into war.
If your project doesn't have a ServletInitializer class, create it.
ServletInitializer.java
package org.o7planning.example;

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(SpringBootTomcatApplication.class);
    }

}
Add the following configuration snippet to the pom.xml:
** pom.xml **
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-tomcat</artifactId>
    <scope>provided</scope>
</dependency>
If there are more than one Application class in your project, please tell the Spring Boot which class will be used for your application.
** pom.xml **
<properties>
        <start-class>org.o7planning.example.OtherSpringBootWebApplication</start-class>
</properties>

3- Install Spring Boot

In the next step, you need to use Maven to create  WAR file. You have to ensure that your Eclipse is using  JDK instead of JRE. If not, en error will occur in this process.
Right click on the Project and select:
  • Run As/Maven Install

At this moment, you will have a  WAR file in the target folder of the project, you can use this file to deploy on the Tomcat Server.
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