Super simple Spring REST service, no Groovy but works with external server as well.

Application.java

package com.gleason.itext;
import java.util.Arrays;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.context.web.SpringBootServletInitializer;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.bind.annotation.PathVariable;

@Configuration
@ComponentScan
@EnableAutoConfiguration
public class Application extends SpringBootServletInitializer {

    public static void main(String[] args) {
        SpringApplication.run(applicationClass, args);
    }

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

    private static Class<Application> applicationClass = Application.class;
}

build.gradle

buildscript {
  repositories {
    mavenLocal()
    mavenCentral()
    maven { url "http://repo.spring.io/snapshot" }
    maven { url "http://repo.spring.io/milestone" }
  }
  dependencies {
    classpath("org.springframework.boot:spring-boot-gradle-plugin:1.1.2.BUILD-SNAPSHOT")
  }
}
apply plugin: 'war'
apply plugin: 'spring-boot'
war { baseName='itext' }
repositories {
  mavenLocal()
  mavenCentral()
  maven { url "http://repo.spring.io/snapshot" }
  maven { url "http://repo.spring.io/milestone" }
}
dependencies {
  compile("org.springframework.boot:spring-boot-starter-web")
  providedRuntime("org.springframework.boot:spring-boot-starter-tomcat")
  testCompile("org.springframework.boot:spring-boot-starter-test")
}

GreetingController.java

package com.gleason.itext.controllers;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class GreetingController {
    @RequestMapping("/")
    public String test(){
      System.out.println("Test");
      return "Test";
    }
}