This post shows how to deploy a spring boot war file to the separate tomcat container in maven.

Step 1 : extends SpringBootServletInitializer subclass and overrides its configure method.

Typically, update your application’s main class to extend SpringBootServletInitializer.
For example:

Before extend:

package net.mzouabi.ng2.server;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.CrossOrigin;@SpringBootApplication
@CrossOrigin(origins = "http://localhost:4200")public class ServerApplication {
   public static void main(String[] args) {
      SpringApplication.run(ServerApplication.class, args);
   }
}

After extend:

package net.mzouabi.ng2.server;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.boot.web.support.SpringBootServletInitializer;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
@CrossOrigin(origins = "http://localhost:4200")
public class ServerApplication extends SpringBootServletInitializer{
   public static void main(String[] args) {
      SpringApplication.run(ServerApplication.class, args);
   }

   @Bean
   public TomcatEmbeddedServletContainerFactory tomcatEmbeddedServletContainerFactory() {
      return new TomcatEmbeddedServletContainerFactory();
   }

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

Step 2: pom.xml changes
need to modify pom.xml to change the packaging to war:
<packaging>war</packaging>

and also need to mark the embedded servlet container dependency as provided.

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

Step 3: run the maven command mvn package.
I got the following output:

and war file created in the project target as I show in follow:

Step 4: Copy the WAR to tomcat webapps.
Here the name is important – whatever filename we choose will be used to map HTTP requests to our application.
I got the following output:

Step 5: After that, test your war file