The plugin can create an https://github.com/opencontainers/image-spec[OCI image] from an executable jar file using https://buildpacks.io/[Cloud Native Buildpacks] (CNB).
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>
<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).
The `build-image` goal requires access to a Docker daemon.
By default, it will communicate with a Docker daemon over a local connection.
This works with https://docs.docker.com/install/[Docker Engine] on all supported platforms without configuration.
Environment variables can be set to configure the `build-image` goal to use the https://minikube.sigs.k8s.io/docs/tasks/docker_daemon/[Docker daemon provided by minikube].
The following table shows the environment variables and their values:
If the Docker images specified by the `builder` or `runImage` parameters are stored in a private Docker image registry that requires authentication, the authentication credentials can be provided using `docker.builderRegistry` parameters.
If the generated Docker image is to be published to a Docker image registry, the authentication credentials can be provided using `docker.publishRegistry` parameters.
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.
NOTE: The plugin detects the target Java compatibility of the project using the compiler's plugin configuration or the `maven.compiler.target` property.
If you need to customize the builder used to create the image or the run image used to launch the built image, configure the plugin as shown in the following example:
This configuration will use a builder image with the name `mine/java-cnb-builder` and the tag `latest`, and the run image named `mine/java-cnb-run` and the tag `latest`.
The following is an example of {paketo-java-reference}/#configuring-the-jvm-version[configuring the JVM version] used by the Paketo Java buildpacks at build time:
If there is a network proxy between the Docker daemon the builder runs in and network locations that buildpacks download artifacts from, you will need to configure the builder to use the proxy.
When using the Paketo builder, this can be accomplished by setting the `HTTPS_PROXY` and/or `HTTP_PROXY` environment variables as show in the following example:
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}`.
By default, the builder will use buildpacks included in the builder image and apply them in a pre-defined order.
An alternative set of buildpacks can be provided to apply buildpacks that are not included in the builder, or to change the order of included buildpacks.
When one or more buildpacks are provided, only the specified buildpacks will be applied.
The following example instructs the builder to use a custom buildpack packaged in a `.tgz` file, followed by a buildpack included in the builder.
The generated image can be published to a Docker registry by enabling a `publish` option and configuring authentication for the registry using `docker.publishRegistry` parameters.
If you need the plugin to communicate with the Docker daemon using a remote connection instead of the default local connection, the connection details can be provided using `docker` parameters as shown in the following example:
If the builder or run image are stored in a private Docker registry that supports user authentication, authentication details can be provided using `docker.builderRegistry` parameters as shown in the following example:
If the builder or run image is stored in a private Docker registry that supports token authentication, the token value can be provided using `docker.builderRegistry` parameters as shown in the following example:
