Spring Boot

= Spring Boot image:https://ci.spring.io/api/v1/teams/spring-boot/pipelines/spring-boot-2.3.x/jobs/build/badge["Build Status", link="https://ci.spring.io/teams/spring-boot/pipelines/spring-boot-2.3.x?groups=Build"] image:https://badges.gitter.im/Join Chat.svg["Chat",link="https://gitter.im/spring-projects/spring-boot?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge"]
:docs: https://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference
:github: https://github.com/spring-projects/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

== Installation and Getting Started
The {docs}/html/[reference documentation] includes detailed
{docs}/html/getting-started.html#getting-started-installing-spring-boot[installation
instructions] as well as a comprehensive
{docs}/html/getting-started.html#getting-started-first-application[getting started]
guide.

Here is a quick teaser of a complete Spring Boot application in Java:

[source,java,indent=0]

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

@RestController
@SpringBootApplication
public class Example {

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

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

}

== Getting help
Having trouble with Spring Boot? We'd like to help!

• Check the {docs}/html/[reference documentation], especially the
  {docs}/html/howto.html#howto[How-to's] -- they provide solutions to the most common
  questions.
• Learn the Spring basics -- Spring Boot builds on many other Spring projects, check
  the https://spring.io[spring.io] web-site for a wealth of reference documentation. If
  you are just starting out with Spring, try one of the https://spring.io/guides[guides].
• If you are upgrading, read the {github}/wiki[release notes] for upgrade instructions and
  "new and noteworthy" features.
• Ask a question - we monitor https://stackoverflow.com[stackoverflow.com] for questions
  tagged with https://stackoverflow.com/tags/spring-boot[`spring-boot`]. You can also chat
  with the community on https://gitter.im/spring-projects/spring-boot[Gitter].
• Report bugs with Spring Boot at {github}/issues[github.com/spring-projects/spring-boot/issues].

== Reporting Issues
Spring Boot uses GitHub's integrated issue tracking system to record bugs and feature
requests. If you want to raise an issue, please follow the recommendations below:

• Before you log a bug, please search the {github}/issues[issue tracker] to see if someone
  has already reported the problem.
• If the issue doesn't already exist, {github}/issues/new[create a new issue].
• Please provide as much information as possible with the issue report, we like to know
  the version of Spring Boot that you are using, as well as your Operating System and
  JVM version.
• If you need to paste code, or include a stack trace use Markdown +++```+++ escapes
  before and after your text.
• If possible try to create a test-case or project that replicates the problem and attach
  it to the issue.

== Building from Source
You don't need to build from source to use Spring Boot (binaries in
https://repo.spring.io[repo.spring.io]), but if you want to try out the latest and
greatest, Spring Boot can be built and published to your local Maven cache using the
https://docs.gradle.org/current/userguide/gradle_wrapper.html[Gradle wrapper]. You also
need JDK 1.8.

[indent=0]

$ ./gradlew publishToMavenLocal

This will build all of the jars and documentation and publish them to your local
Maven cache. It won't run any of the tests. If you want to build everything, use the
build task:

[indent=0]

$ ./gradlew build

Also see link:CONTRIBUTING.adoc[CONTRIBUTING.adoc] if you wish to submit pull requests,
and in particular please fill out the
https://support.springsource.com/spring_committer_signup[Contributor's Agreement]
before your first change, however trivial.

== Modules
There are a number of modules in Spring Boot, here is a quick overview:

=== 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, Jetty or Undertow)
• First class externalized configuration support
• Convenience ApplicationContext initializers, including support for sensible logging
  defaults

=== 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.

=== 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.

=== 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.

=== spring-boot-actuator
Actuator endpoints let you monitor and interact with your application.
Spring Boot Actuator provides the infrastructure required for actuator endpoints. It contains
annotation support for actuator endpoints. Out of the box, this module provides a number of endpoints
including the HealthEndpoint, EnvironmentEndpoint, BeansEndpoint and many more.

=== spring-boot-actuator-autoconfigure
This provides auto-configuration for actuator endpoints based on the content of the classpath and a set of properties.
For instance, if Micrometer is on the classpath, it will auto-configure the MetricsEndpoint.
It contains configuration to expose endpoints over HTTP or JMX.
Just like Spring Boot AutoConfigure, this will back away as the user starts to define their own beans.

=== spring-boot-test
This module contains core items and annotations that can be helpful when testing your application.

=== spring-boot-test-autoconfigure
Like other Spring Boot auto-configuration modules, spring-boot-test-autoconfigure, provides auto-configuration
for tests based on the classpath. It includes a number of annotations that can be used to automatically
configure a slice of your application that needs to be tested.

=== 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
link:spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin[Gradle] or
link:spring-boot-project/spring-boot-tools/spring-boot-maven-plugin[Maven] plugin.

=== spring-boot-devtools
The spring-boot-devtools module provides additional development-time features such as automatic restarts,
for a smoother application development experience. Developer tools are automatically disabled when
running a fully packaged application.

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

== Guides
The https://spring.io/[spring.io] site contains several guides that show how to use Spring
Boot step-by-step:

• https://spring.io/guides/gs/spring-boot/[Building an Application with Spring Boot] is a
  very basic guide that shows you how to create a simple application, run it and add some
  management services.
• https://spring.io/guides/gs/actuator-service/[Building a RESTful Web Service with Spring
  Boot Actuator] is a guide to creating a REST web service and also shows how the server
  can be configured.
• https://spring.io/guides/gs/convert-jar-to-war/[Converting a Spring Boot JAR Application
  to a WAR] shows you how to run applications in a web server as a WAR file.

== License
Spring Boot is Open Source software released under the
https://www.apache.org/licenses/LICENSE-2.0.html[Apache 2.0 license].