Spring Boot

Spring Boot makes it easy to create Spring-powered, production-grade applications and services with absolute minimum fuss. It takes an opinionated view of the Spring platform so that new and existing users can quickly get to the bits they need.

You can use Spring Boot to create stand-alone Java applications that can be started using java -jar or more traditional WAR deployments. We also provide a command line tool that runs spring scripts.

Our primary goals are:

• Provide a radically faster and widely accessible getting started experience for all Spring development
• Be opinionated out of the box, but get out of the way quickly as requirements start to diverge from the defaults
• Provide a range of non-functional features that are common to large classes of projects (e.g. embedded servers, security, metrics, health checks, externalized configuration)
• Absolutely no code generation and no requirement for XML configuration

Installing the CLI

The Spring Boot command line tool uses Groovy underneath so that we can present simple Spring snippets that can 'just run'. You don't need the CLI to get started (see the Java example below), but it's the quickest way to get a Spring application off the ground. You need Java SDK v1.6 or higher to run the command line tool (there are even some issues with the 1.7.0_25 build of openjdk, so stick to earlier builds or use 1.6 for preference). You should check your current Java installation before you begin:

$ java -version

MacOS with Brew

If you are on a Mac and using homebrew, all you need do to install the Spring Boot CLI is:

$ brew install spring-boot-cli

It will install /usr/local/bin/spring. Now you can jump right to a quick start example.

Note: If you don't see the formula, you're installation of brew might be out-of-date. Just execute brew update and try again

Cross Platform java - jar

An alternative way to install Spring Boot CLI is to downloaded it from our Maven repository, and then you can use a shell alias:

$ wget http://maven.springframework.org/milestone/org/springframework/boot/spring-boot-cli/0.5.0.M1/spring-boot-cli-0.5.0.M1.jar
$ alias spring="java -jar `pwd`/spring-boot-cli-0.5.0.M1.jar"

If you don't have wget installed on your system you might have curl (with -o for setting the output filename). Windows users will need cygwin to use the alias command, but they can run java -jar directly and that will work.

Complete installation including a downloadable .zip with a shell script TBD.

Quick Start Script Example

Here's a really simple web application. Create a file called app.groovy:

@Controller
class ThisWillActuallyRun {
	
	@RequestMapping("/")
	@ResponseBody
	String home() {
		return "Hello World!"
	}
	
}

Then run it from a shell:

$ spring run app.groovy --verbose
$ curl localhost:8080
Hello World!

It might take a few minutes the first time you do this while some dependencies are downloaded (which is why we added the --verbose option - you can remove that if you prefer). If you are a maven user and have a fully loaded local cache with all the required dependencies you will find it is much faster.

## Quick Start Java Example If you don't want to use the command line tool, or you would rather work using Java and an IDE you can. Create a `pom.xml` (or the equivalent with your favourite build system):

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <modelVersion>4.0.0</modelVersion>
    <artifactId>myproject</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>0.5.0.M1</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>${project.groupId}</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
    <!-- TODO: remove once Spring Boot is in Maven Central -->
    <repositories>
        <repository>
            <id>spring-milestone</id>
            <url>http://repo.springsource.org/milestone</url>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>spring-milestone</id>
            <url>http://repo.springsource.org/milestone</url>
        </pluginRepository>
    </pluginRepositories>
</project>

Then just add a class in src/main/java with a main() method that calls SpringApplication and add @EnableAutoConfiguration, e.g:

src/main/java/SampleController.java

import org.springframework.boot.*;
import org.springframework.boot.autoconfigure.*;
import org.springframework.stereotype.*;
import org.springframework.web.bind.annotation.*;

@Controller
@EnableAutoConfiguration
public class SampleController {

    @RequestMapping("/")
	@ResponseBody
	String home() {
		return "Hello World!";
	}

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

You can run this application by building a jar and executing it:

$ mvn package
$ java -jar target/myproject-0.0.1-SNAPSHOT.jar
... Spring starting up ...

and in anonther terminal:

$ curl localhost:8080
Hello World!

Spring Boot Modules

There are a number of modules in Spring Boot. Here are the important ones:

spring-boot

The main library providing features that support the other parts of Spring Boot, these include:

• The SpringApplication class, providing static convenience methods that make it easy to write a stand-alone Spring Application. Its sole job is to create and refresh an appropriate Spring ApplicationContext
• Embedded web applications with a choice of container (Tomcat or Jetty for now)
• First class externalized configuration support
• Convenience ApplicationContext initializers, including support for sensible logging defaults.

See spring-boot/README.md.

spring-boot-autoconfigure

Spring Boot can configure large parts of common applications based on the content of their classpath. A single @EnableAutoConfiguration annotation triggers auto-configuration of the Spring context.

Auto-configuration attempts to deduce which beans a user might need. For example, If 'HSQLDB' is on the classpath, and the user has not configured any database connections, then they probably want an in-memory database to be defined. Auto-configuration will always back away as the user starts to define their own beans.

See spring-boot-autoconfigure/README.md.

spring-boot-starters

Starters are a set of convenient dependency descriptors that you can include in your application. You get a one-stop-shop for all the Spring and related technology that you need without having to hunt through sample code and copy paste loads of dependency descriptors. For example, if you want to get started using Spring and JPA for database access just include the spring-boot-starter-data-jpa dependency in your project, and you are good to go.

See spring-boot-starters/README.md.

spring-boot-cli

The Spring command line application compiles and runs Groovy source, making it super easy to write the absolute minimum of code to get an application running. Spring CLI can also watch files, automatically recompiling and restarting when they change.

See spring-boot-cli/README.md.

spring-boot-actuator

Spring Boot Actuator provides additional auto-configuration to decorate your application with features that make it instantly deployable and supportable in production. For instance if you are writing a JSON web service then it will provide a server, security, logging, externalized configuration, management endpoints, an audit abstraction, and more. If you want to switch off the built in features, or extend or replace them, it makes that really easy as well.

See spring-boot-actuator/README.md.

spring-boot-loader

Spring Boot Loader provides the secret sauce that allows you to build a single jar file that can be launched using java -jar. Generally you will not need to use spring-boot-loader directly but instead work with the Gradle or Maven plugin.

See spring-boot-loader/README.md.

Samples

Groovy samples for use with the command line application are available in spring-boot-cli/samples. To run the CLI samples type spring run <sample>.groovy from samples directory.

Java samples are available in spring-boot-samples and should be build with maven and run use java -jar target/<sample>.jar. The following java samples are provided:

• spring-boot-sample-simple - A simple command line application
• spring-boot-sample-tomcat - Embedded Tomcat
• spring-boot-sample-jetty - Embedded Jetty
• spring-boot-sample-actuator - Simple REST service with production features
• spring-boot-sample-actuator-ui - A web UI example with production features
• spring-boot-sample-web-ui - A thymeleaf web application
• spring-boot-sample-web-static - A web application service static files
• spring-sample-batch - Define and run a Batch job in a few lines of code
• spring-sample-data-jpa - Spring Data JPA + Hibernate + HSQLDB
• spring-boot-sample-integration - A spring integration application
• spring-boot-sample-profile - example showing Spring's @profile support
• spring-boot-sample-traditional - shows more traditional WAR packaging (but also executable using java -jar)
• spring-boot-sample-xml - Example show how Spring Boot can be mixed with traditional XML configuration (we generally recommend using Java @Configuration whenever possible)

Building Spring Boot from source You don't need to build from

source to use Spring Boot (it's in the Maven repositories), but if you want to try out the latest and greatest, Spring Boot can be built with maven v3.0 or above.

$ mvn clean install

Also see CONTRIBUTING.md if you wish to submit pull requests.