13. Build systems

13. Build systems
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It is strongly recommended that you choose a build system that supports dependency management, and one that can consume artifacts published to the “Maven Central” repository. We would recommend that you choose Maven or Gradle. It is possible to get Spring Boot to work with other build systems (Ant for example), but they will not be particularly well supported.

13.1 Dependency management

Each release of Spring Boot provides a curated list of dependencies it supports. In practice, you do not need to provide a version for any of these dependencies in your build configuration as Spring Boot is managing that for you. When you upgrade Spring Boot itself, these dependencies will be upgraded as well in a consistent way.

	Note
	You can still specify a version and override Spring Boot’s recommendations if you feel that’s necessary.

The curated list contains all the spring modules that you can use with Spring Boot as well as a refined list of third party libraries. The list is available as a standard Bills of Materials (spring-boot-dependencies) and additional dedicated support for Maven and Gradle are available as well.

	Warning
	Each release of Spring Boot is associated with a base version of the Spring Framework so we highly recommend you to not specify its version on your own.

13.2 Maven

Maven users can inherit from the spring-boot-starter-parent project to obtain sensible defaults. The parent project provides the following features:

Java 1.6 as the default compiler level.
UTF-8 source encoding.
A Dependency Management section, allowing you to omit <version> tags for common dependencies, inherited from the spring-boot-dependencies POM.
Sensible resource filtering.
Sensible plugin configuration (exec plugin, surefire, Git commit ID, shade).
Sensible resource filtering for application.properties and application.yml including profile-specific files (e.g. application-foo.properties and application-foo.yml)

On the last point: since the default config files accept Spring style placeholders (${…}) the Maven filtering is changed to use @..@ placeholders (you can override that with a Maven property resource.delimiter).

13.2.1 Inheriting the starter parent

To configure your project to inherit from the spring-boot-starter-parent simply set the parent:

<!-- Inherit defaults from Spring Boot -->
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.21.RELEASE</version>
</parent>

	Note
	You should only need to specify the Spring Boot version number on this dependency. If you import additional starters, you can safely omit the version number.

With that setup, you can also override individual dependencies by overriding a property in your own project. For instance, to upgrade to another Spring Data release train you’d add the following to your pom.xml.

<properties>
    <spring-data-releasetrain.version>Fowler-SR2</spring-data-releasetrain.version>
</properties>

	Tip
	Check the `spring-boot-dependencies` pom for a list of supported properties.

13.2.2 Using Spring Boot without the parent POM

Not everyone likes inheriting from the spring-boot-starter-parent POM. You may have your own corporate standard parent that you need to use, or you may just prefer to explicitly declare all your Maven configuration.

If you don’t want to use the spring-boot-starter-parent, you can still keep the benefit of the dependency management (but not the plugin management) by using a scope=import dependency:

<dependencyManagement>
     <dependencies>
        <dependency>
            <!-- Import dependency management from Spring Boot -->
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-dependencies</artifactId>
            <version>1.5.21.RELEASE</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

That setup does not allow you to override individual dependencies using a property as explained above. To achieve the same result, you’d need to add an entry in the dependencyManagement of your project before the spring-boot-dependencies entry. For instance, to upgrade to another Spring Data release train you’d add the following to your pom.xml.

<dependencyManagement>
    <dependencies>
        <!-- Override Spring Data release train provided by Spring Boot -->
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-releasetrain</artifactId>
            <version>Fowler-SR2</version>
            <scope>import</scope>
            <type>pom</type>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-dependencies</artifactId>
            <version>1.5.21.RELEASE</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

	Note
	In the example above, we specify a BOM but any dependency type can be overridden that way.

13.2.3 Changing the Java version

The spring-boot-starter-parent chooses fairly conservative Java compatibility. If you want to follow our recommendation and use a later Java version you can add a java.version property:

<properties>
    <java.version>1.8</java.version>
</properties>

13.2.4 Using the Spring Boot Maven plugin

Spring Boot includes a Maven plugin that can package the project as an executable jar. Add the plugin to your <plugins> section if you want to use it:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

	Note
	If you use the Spring Boot starter parent pom, you only need to add the plugin, there is no need for to configure it unless you want to change the settings defined in the parent.

13.3 Gradle

Gradle users can directly import ‘starters’ in their dependencies section. Unlike Maven, there is no “super parent” to import to share some configuration.

repositories {
    jcenter()
}

dependencies {
    compile("org.springframework.boot:spring-boot-starter-web:1.5.21.RELEASE")
}

The spring-boot-gradle-plugin is also available and provides tasks to create executable jars and run projects from source. It also provides dependency management that, among other capabilities, allows you to omit the version number for any dependencies that are managed by Spring Boot:

plugins {
    id 'org.springframework.boot' version '1.5.21.RELEASE'
    id 'java'
}


repositories {
    jcenter()
}

dependencies {
    compile("org.springframework.boot:spring-boot-starter-web")
    testCompile("org.springframework.boot:spring-boot-starter-test")
}

13.4 Ant

It is possible to build a Spring Boot project using Apache Ant+Ivy. The spring-boot-antlib “AntLib” module is also available to help Ant create executable jars.

To declare dependencies a typical ivy.xml file will look something like this:

<ivy-module version="2.0">
    <info organisation="org.springframework.boot" module="spring-boot-sample-ant" />
    <configurations>
        <conf name="compile" description="everything needed to compile this module" />
        <conf name="runtime" extends="compile" description="everything needed to run this module" />
    </configurations>
    <dependencies>
        <dependency org="org.springframework.boot" name="spring-boot-starter"
            rev="${spring-boot.version}" conf="compile" />
    </dependencies>
</ivy-module>

A typical build.xml will look like this:

<project
    xmlns:ivy="antlib:org.apache.ivy.ant"
    xmlns:spring-boot="antlib:org.springframework.boot.ant"
    name="myapp" default="build">

    <property name="spring-boot.version" value="1.5.21.RELEASE" />

    <target name="resolve" description="--> retrieve dependencies with ivy">
        <ivy:retrieve pattern="lib/[conf]/[artifact]-[type]-[revision].[ext]" />
    </target>

    <target name="classpaths" depends="resolve">
        <path id="compile.classpath">
            <fileset dir="lib/compile" includes="*.jar" />
        </path>
    </target>

    <target name="init" depends="classpaths">
        <mkdir dir="build/classes" />
    </target>

    <target name="compile" depends="init" description="compile">
        <javac srcdir="src/main/java" destdir="build/classes" classpathref="compile.classpath" />
    </target>

    <target name="build" depends="compile">
        <spring-boot:exejar destfile="build/myapp.jar" classes="build/classes">
            <spring-boot:lib>
                <fileset dir="lib/runtime" />
            </spring-boot:lib>
        </spring-boot:exejar>
    </target>
</project>

	Tip
	See the Section 85.10, “Build an executable archive from Ant without using spring-boot-antlib” “How-to” if you don’t want to use the `spring-boot-antlib` module.

13.5 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.

The starters contain a lot of the dependencies that you need to get a project up and running quickly and with a consistent, supported set of managed transitive dependencies.

What’s in a name

All official starters follow a similar naming pattern; spring-boot-starter-*, where * is a particular type of application. This naming structure is intended to help when you need to find a starter. The Maven integration in many IDEs allow you to search dependencies by name. For example, with the appropriate Eclipse or STS plugin installed, you can simply hit ctrl-space in the POM editor and type “spring-boot-starter” for a complete list.

As explained in the Creating your own starter section, third party starters should not start with spring-boot as it is reserved for official Spring Boot artifacts. A third-party starter for acme will be typically named acme-spring-boot-starter.

The following application starters are provided by Spring Boot under the org.springframework.boot group:

Table 13.1. Spring Boot application starters

Name	Description	Pom
`spring-boot-starter`	Core starter, including auto-configuration support, logging and YAML	Pom
`spring-boot-starter-activemq`	Starter for JMS messaging using Apache ActiveMQ	Pom
`spring-boot-starter-amqp`	Starter for using Spring AMQP and Rabbit MQ	Pom
`spring-boot-starter-aop`	Starter for aspect-oriented programming with Spring AOP and AspectJ	Pom
`spring-boot-starter-artemis`	Starter for JMS messaging using Apache Artemis	Pom
`spring-boot-starter-batch`	Starter for using Spring Batch	Pom
`spring-boot-starter-cache`	Starter for using Spring Framework’s caching support	Pom
`spring-boot-starter-cloud-connectors`	Starter for using Spring Cloud Connectors which simplifies connecting to services in cloud platforms like Cloud Foundry and Heroku	Pom
`spring-boot-starter-data-cassandra`	Starter for using Cassandra distributed database and Spring Data Cassandra	Pom
`spring-boot-starter-data-couchbase`	Starter for using Couchbase document-oriented database and Spring Data Couchbase	Pom
`spring-boot-starter-data-elasticsearch`	Starter for using Elasticsearch search and analytics engine and Spring Data Elasticsearch	Pom
`spring-boot-starter-data-gemfire`	Starter for using GemFire distributed data store and Spring Data GemFire	Pom
`spring-boot-starter-data-jpa`	Starter for using Spring Data JPA with Hibernate	Pom
`spring-boot-starter-data-ldap`	Starter for using Spring Data LDAP	Pom
`spring-boot-starter-data-mongodb`	Starter for using MongoDB document-oriented database and Spring Data MongoDB	Pom
`spring-boot-starter-data-neo4j`	Starter for using Neo4j graph database and Spring Data Neo4j	Pom
`spring-boot-starter-data-redis`	Starter for using Redis key-value data store with Spring Data Redis and the Jedis client	Pom
`spring-boot-starter-data-rest`	Starter for exposing Spring Data repositories over REST using Spring Data REST	Pom
`spring-boot-starter-data-solr`	Starter for using the Apache Solr search platform with Spring Data Solr	Pom
`spring-boot-starter-freemarker`	Starter for building MVC web applications using FreeMarker views	Pom
`spring-boot-starter-groovy-templates`	Starter for building MVC web applications using Groovy Templates views	Pom
`spring-boot-starter-hateoas`	Starter for building hypermedia-based RESTful web application with Spring MVC and Spring HATEOAS	Pom
`spring-boot-starter-integration`	Starter for using Spring Integration	Pom
`spring-boot-starter-jdbc`	Starter for using JDBC with the Tomcat JDBC connection pool	Pom
`spring-boot-starter-jersey`	Starter for building RESTful web applications using JAX-RS and Jersey. An alternative to `spring-boot-starter-web`	Pom
`spring-boot-starter-jooq`	Starter for using jOOQ to access SQL databases. An alternative to `spring-boot-starter-data-jpa` or `spring-boot-starter-jdbc`	Pom
`spring-boot-starter-jta-atomikos`	Starter for JTA transactions using Atomikos	Pom
`spring-boot-starter-jta-bitronix`	Starter for JTA transactions using Bitronix	Pom
`spring-boot-starter-jta-narayana`	Spring Boot Narayana JTA Starter	Pom
`spring-boot-starter-mail`	Starter for using Java Mail and Spring Framework’s email sending support	Pom
`spring-boot-starter-mobile`	Starter for building web applications using Spring Mobile	Pom
`spring-boot-starter-mustache`	Starter for building MVC web applications using Mustache views	Pom
`spring-boot-starter-security`	Starter for using Spring Security	Pom
`spring-boot-starter-social-facebook`	Starter for using Spring Social Facebook	Pom
`spring-boot-starter-social-linkedin`	Stater for using Spring Social LinkedIn	Pom
`spring-boot-starter-social-twitter`	Starter for using Spring Social Twitter	Pom
`spring-boot-starter-test`	Starter for testing Spring Boot applications with libraries including JUnit, Hamcrest and Mockito	Pom
`spring-boot-starter-thymeleaf`	Starter for building MVC web applications using Thymeleaf views	Pom
`spring-boot-starter-validation`	Starter for using Java Bean Validation with Hibernate Validator	Pom
`spring-boot-starter-web`	Starter for building web, including RESTful, applications using Spring MVC. Uses Tomcat as the default embedded container	Pom
`spring-boot-starter-web-services`	Starter for using Spring Web Services	Pom
`spring-boot-starter-websocket`	Starter for building WebSocket applications using Spring Framework’s WebSocket support	Pom

In addition to the application starters, the following starters can be used to add production ready features:

Table 13.2. Spring Boot production starters

Name	Description	Pom
`spring-boot-starter-actuator`	Starter for using Spring Boot’s Actuator which provides production ready features to help you monitor and manage your application	Pom
`spring-boot-starter-remote-shell`	Starter for using the CRaSH remote shell to monitor and manage your application over SSH. Deprecated since 1.5	Pom

Finally, Spring Boot also includes some starters that can be used if you want to exclude or swap specific technical facets:

Table 13.3. Spring Boot technical starters

Name	Description	Pom
`spring-boot-starter-jetty`	Starter for using Jetty as the embedded servlet container. An alternative to `spring-boot-starter-tomcat`	Pom
`spring-boot-starter-log4j2`	Starter for using Log4j2 for logging. An alternative to `spring-boot-starter-logging`	Pom
`spring-boot-starter-logging`	Starter for logging using Logback. Default logging starter	Pom
`spring-boot-starter-tomcat`	Starter for using Tomcat as the embedded servlet container. Default servlet container starter used by `spring-boot-starter-web`	Pom
`spring-boot-starter-undertow`	Starter for using Undertow as the embedded servlet container. An alternative to `spring-boot-starter-tomcat`	Pom

	Tip
	For a list of additional community contributed starters, see the README file in the `spring-boot-starters` module on GitHub.