[[build-image]]
== Packaging OCI Images

The plugin can create an https://github.com/opencontainers/image-spec[OCI image] using https://buildpacks.io/[Cloud Native Buildpacks].
Images can be built using the `build-image` goal and a local Docker installation.

The easiest way to get started is to to invoke `mvn spring-boot:build-image` on a project.
It is possible to automate the creation of an image whenever the `package` phase is invoked, as shown in the following example:

[source,xml,indent=0,subs="verbatim,attributes"]
----
	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
				<version>{gradle-project-version}</version>
				<executions>
					<execution>
						<goals>
							<goal>build-image</goal>
						</goals>
					</execution>
				</executions>
			</plugin>
		</plugins>
	</build>
----

TIP: While the buildpack runs from an <<repackage,executable archive>>, it is not necessary to execute the `repackage` goal first as the executable archive is created automatically if necessary.
When the `build-image` repackages the application, it applies the same settings as the `repackage` goal would, i.e. dependencies can be excluded using one of the exclude options, and Devtools is automatically excluded by default (you can control that using the `excludeDevtools` property).



[[build-image-customization]]
=== Image Customizations
The plugin invokes a {buildpacks-reference}/concepts/components/builder/[builder] to orchestrate the generation of an image.
The builder includes multiple {buildpacks-reference}/concepts/components/buildpack[buildpacks] that can inspect the application to influence the generated image.
By default, the plugin chooses a builder image.
The name of the generated image is deduced from project properties.

The `image` parameter allows to configure how the builder should operate on the project.
The following table summarizes the available properties and their default values:

|===
| Property | Description | Default value

| `builder`
| Name of the Builder image to use.
| `cloudfoundry/cnb:0.0.53-bionic`

| `name`
| {spring-boot-api}/buildpack/platform/docker/type/ImageReference.html#of-java.lang.String-[Image name] for the generated image.
| `docker.io/library/${project.artifactId}:${project.version}`

| `env`
| Environment variables that should be passed to the builder.
|

| `cleanCache`
| Whether to clean the cache before building.
| `false`

| `verboseLogging`
| Enables verbose logging of builder operations.
| `false`
|===

For more details, see <<build-image-example-custom-image-builder,custom image builder>> and <<build-image-example-custom-image-name,custom image name>>.

include::goals/build-image.adoc[leveloffset=+1]



[[build-image-examples]]
=== Examples



[[build-image-example-custom-image-builder]]
==== Custom Image Builder
If you need to customize the builder used to create the image, configure yours as shown in the following example:

[source,xml,indent=0,subs="verbatim,attributes"]
----
	<project>
		<build>
			<plugins>
				<plugin>
					<groupId>org.springframework.boot</groupId>
					<artifactId>spring-boot-maven-plugin</artifactId>
					<version>{gradle-project-version}</version>
					<configuration>
						<image>
							<builder>mine/java-cnb-builder</builder>
						</image>
					</configuration>
				</plugin>
			</plugins>
		</build>
	</project>
----

This configuration will use a builder image with the name `mine/java-cnb-builder` and the tag `latest`.

If the builder exposes configuration options, those can be set using the `env` attributes, as shown in the following example:

[source,xml,indent=0,subs="verbatim,attributes"]
----
	<project>
		<build>
			<plugins>
				<plugin>
					<groupId>org.springframework.boot</groupId>
					<artifactId>spring-boot-maven-plugin</artifactId>
					<version>{gradle-project-version}</version>
					<configuration>
						<image>
							<builder>mine/java-cnb-builder</builder>
							<env>
								<BP_JAVA_VERSION>13.0.1</BP_JAVA_VERSION>
							</env>
						</image>
					</configuration>
				</plugin>
			</plugins>
		</build>
	</project>
----

The example above assumes that `mine/java-cnb-builder` defines a `BP_JAVA_VERSION` property (typically used to customize the JDK version the image should use).



[[build-image-example-custom-image-name]]
==== Custom Image Name
By default, the image name is inferred from the `artifactId` and the `version` of the project, something like `docker.io/library/${project.artifactId}:${project.version}`.
You can take control over the name, as shown in the following example:

[source,xml,indent=0,subs="verbatim,attributes"]
----
	<project>
		<build>
			<plugins>
				<plugin>
					<groupId>org.springframework.boot</groupId>
					<artifactId>spring-boot-maven-plugin</artifactId>
					<version>{gradle-project-version}</version>
					<configuration>
						<image>
							<name>example.com/library/${project.artifactId}</name>
						</image>
					</configuration>
				</plugin>
			</plugins>
		</build>
	</project>
----

Note that this configuration does not provide an explicit tag so `latest` is used.
It is possible to specify a tag as well, either using `${project.version}`, any property available in the build or a hardcoded version.