[[managing-dependencies]]
== Managing dependencies

When you apply the {dependency-management-plugin}[`io.spring.dependency-management`]
plugin, Spring Boot's plugin will
automatically <<reacting-to-other-plugins-dependency-management,import the
`spring-boot-dependencies` bom>> from the version of Spring Boot that you are using.
This provides a similar dependency management experience to the one that's enjoyed by
Maven users. For example, it allows you to omit version numbers when declaring
dependencies that are managed in the bom. To make use of this functionality, simply
declare dependencies in the usual way but omit the version number:

[source,groovy,indent=0,subs="verbatim",role="primary"]
.Groovy
----
include::../gradle/managing-dependencies/dependencies.gradle[tags=dependencies]
----

[source,kotlin,indent=0,subs="verbatim",role="secondary"]
.Kotlin
----
include::../gradle/managing-dependencies/dependencies.gradle.kts[tags=dependencies]
----


[[managing-dependencies-customizing]]
=== Customizing managed versions

The `spring-boot-dependencies` bom that is automatically imported when the dependency
management plugin is applied uses properties to control the versions of the dependencies
that it manages. Please refer to the {github-code}/spring-boot-project/spring-boot-dependencies/pom.xml[bom]
for a complete list of these properties.

To customize a managed version you set its corresponding property. For example, to
customize the version of SLF4J which is controlled by the `slf4j.version` property:

[source,groovy,indent=0,subs="verbatim",role="primary"]
.Groovy
----
include::../gradle/managing-dependencies/custom-version.gradle[tags=custom-version]
----

[source,kotlin,indent=0,subs="verbatim",role="secondary"]
.Kotlin
----
include::../gradle/managing-dependencies/custom-version.gradle.kts[tags=custom-version]
----


WARNING: Each Spring Boot release is designed and tested against a specific set of
third-party dependencies. Overriding versions may cause compatibility issues and should
be done with care.



[[managing-dependencies-using-in-isolation]]
=== Using Spring Boot's dependency management in isolation

Spring Boot's dependency management can be used in a project without applying Spring
Boot's plugin to that project. The `SpringBootPlugin` class provides a `BOM_COORDINATES`
constant that can be used to import the bom without having to know its group ID,
artifact ID, or version.

First, configure the project to depend on the Spring Boot plugin but do not apply it:

ifeval::["{version-type}" == "RELEASE"]
[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
.Groovy
----
include::../gradle/managing-dependencies/depend-on-plugin-release.gradle[]
----

[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
.Kotlin
----
include::../gradle/managing-dependencies/depend-on-plugin-release.gradle.kts[]
----
endif::[]
ifeval::["{version-type}" == "MILESTONE"]
[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
.Groovy
----
include::../gradle/managing-dependencies/depend-on-plugin-milestone.gradle[]
----
[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
.Kotlin
----
include::../gradle/managing-dependencies/depend-on-plugin-release.gradle.kts[]
----
endif::[]
ifeval::["{version-type}" == "SNAPSHOT"]
[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
.Groovy
----
include::../gradle/managing-dependencies/depend-on-plugin-snapshot.gradle[]
----
[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
.Kotlin
----
include::../gradle/managing-dependencies/depend-on-plugin-release.gradle.kts[]
----
endif::[]

The Spring Boot plugin's dependency on the dependency management plugin means that you
can use the dependency management plugin without having to declare a dependency on it.
This also means that you will automatically use the same version of the dependency
management plugin as Spring Boot uses.

Apply the dependency management plugin and then configure it to import Spring Boot's bom:

[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
.Groovy
----
include::../gradle/managing-dependencies/configure-bom.gradle[tags=configure-bom]
----

[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
.Kotlin
----
include::../gradle/managing-dependencies/configure-bom.gradle.kts[tags=configure-bom]
----


The Kotlin code above is a bit awkward. That's because we're using the imperative way of
applying the dependency management plugin.

We can make the code less awkward by applying the plugin from the root parent project, or
by using the `plugins` block as we're doing for the Spring Boot plugin. A downside of this
method is that it forces us to specify the version of the dependency management plugin:

[source,kotlin,indent=0,subs="verbatim,attributes"]
----
include::../gradle/managing-dependencies/configure-bom-with-plugins.gradle.kts[tags=configure-bom]
----


[[managing-dependencies-learning-more]]
=== Learning more

To learn more about the capabilities of the dependency management plugin, please refer to
its {dependency-management-plugin-documentation}[documentation].
