Add support for publishing docker images to a registry

This commit adds options to the Maven and Gradle plugins to publish
to a Docker registry the image generated by the image-building goal
and task.

The Docker registry auth configuration added in an earlier commit
was modified to accept separate auth configs for the builder/run
image and the generated image, since it is likely these images will
be stored in separate registries or repositories with distinct
auth required for each.

Fixes gh-21001

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/asciidoc/packaging-oci-image.adoc

@@ -56,11 +56,14 @@ For more details, see also <<build-image-example-docker,examples>>.
 
 [[build-image-docker-registry]]
 === Docker Registry
-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.registry` properties.
-Properties are provided for user authentication or identity token authentication.
-Consult the documentation for the Docker registry being used to store builder or run images for further information on supported authentication methods.
+If the Docker images specified by the `builder` or `runImage` properties are stored in a private Docker image registry that requires authentication, the authentication credentials can be provided using `docker.builderRegistry` properties.
 
-The following table summarizes the available properties:
+If the generated Docker image is to be published to a Docker image registry, the authentication credentials can be provided using `docker.publishRegistry` properties.
+
+Properties are provided for user authentication or identity token authentication.
+Consult the documentation for the Docker registry being used to store images for further information on supported authentication methods.
+
+The following table summarizes the available properties for `docker.builderRegistry` and `docker.publishRegistry`:
 
 |===
 | Property | Description
@@ -133,6 +136,11 @@ Acceptable values are `ALWAYS`, `NEVER`, and `IF_NOT_PRESENT`.
 |
 | Enables verbose logging of builder operations.
 | `false`
+
+| `publish`
+| `--publishImage`
+| Whether to publish the generated image to a Docker registry.
+| `false`
 |===
 
 NOTE: The plugin detects the target Java compatibility of the project using the JavaPlugin's `targetCompatibility` property.
@@ -236,6 +244,29 @@ The image name can be specified on the command line as well, as shown in this ex
 	$ gradle bootBuildImage --imageName=example.com/library/my-app:v1
 ----
 
+[[build-image-example-publish]]
+==== Image Publishing
+The generated image can be published to a Docker registry by enabling a `publish` option and configuring authentication for the registry using `docker.publishRegistry` properties.
+
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
+----
+include::../gradle/packaging/boot-build-image-publish.gradle[tags=publish]
+----
+
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/packaging/boot-build-image-publish.gradle.kts[tags=publish]
+----
+
+The publish option can be specified on the command line as well, as shown in this example:
+
+[indent=0]
+----
+	$ gradle bootBuildImage --imageName=docker.example.com/library/my-app:v1 --publishImage
+----
+
 [[build-image-example-docker]]
 ==== Docker Configuration
 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` properties as shown in the following example:
@@ -252,7 +283,7 @@ include::../gradle/packaging/boot-build-image-docker-host.gradle[tags=docker-hos
 include::../gradle/packaging/boot-build-image-docker-host.gradle.kts[tags=docker-host]
 ----
 
-If the builder or run image are stored in a private Docker registry that supports user authentication, authentication details can be provided using `docker.registry` properties 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.buiderRegistry` properties as shown in the following example:
 
 [source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
 .Groovy
@@ -266,7 +297,7 @@ include::../gradle/packaging/boot-build-image-docker-auth-user.gradle[tags=docke
 include::../gradle/packaging/boot-build-image-docker-auth-user.gradle.kts[tags=docker-auth-user]
 ----
 
-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.registry` 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` as shown in the following example:
 
 [source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
 .Groovy

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-build-image-docker-auth-token.gradle

@@ -10,7 +10,7 @@ bootJar {
 // tag::docker-auth-token[]
 bootBuildImage {
 	docker {
-		registry {
+		builderRegistry {
 			token = "9cbaf023786cd7..."
 		}
 	}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-build-image-docker-auth-token.gradle.kts

@@ -13,7 +13,7 @@ tasks.getByName<BootJar>("bootJar") {
 // tag::docker-auth-token[]
 tasks.getByName<BootBuildImage>("bootBuildImage") {
 	docker {
-		registry {
+		builderRegistry {
 			token = "9cbaf023786cd7..."
 		}
 	}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-build-image-docker-auth-user.gradle

@@ -10,7 +10,7 @@ bootJar {
 // tag::docker-auth-user[]
 bootBuildImage {
 	docker {
-		registry {
+		builderRegistry {
 			username = "user"
 			password = "secret"
 			url = "https://docker.example.com/v1/"

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-build-image-docker-auth-user.gradle.kts

@@ -13,7 +13,7 @@ tasks.getByName<BootJar>("bootJar") {
 // tag::docker-auth-user[]
 tasks.getByName<BootBuildImage>("bootBuildImage") {
 	docker {
-		registry {
+		builderRegistry {
 			username = "user"
 			password = "secret"
 			url = "https://docker.example.com/v1/"

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-build-image-publish.gradle

@@ -0,0 +1,23 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '{gradle-project-version}'
+}
+
+bootJar {
+	mainClassName 'com.example.ExampleApplication'
+}
+
+// tag::publish[]
+bootBuildImage {
+	imageName = "docker.example.com/library/${project.name}"
+	publish = true
+	docker {
+		publishRegistry {
+			username = "user"
+			password = "secret"
+			url = "https://docker.example.com/v1/"
+			email = "user@example.com"
+		}
+	}
+}
+// end::publish[]

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-build-image-publish.gradle.kts

@@ -0,0 +1,26 @@
+import org.springframework.boot.gradle.tasks.bundling.BootJar
+import org.springframework.boot.gradle.tasks.bundling.BootBuildImage
+
+plugins {
+	java
+	id("org.springframework.boot") version "{gradle-project-version}"
+}
+
+tasks.getByName<BootJar>("bootJar") {
+	mainClassName = "com.example.ExampleApplication"
+}
+
+// tag::publish[]
+tasks.getByName<BootBuildImage>("bootBuildImage") {
+	imageName = "docker.example.com/library/${project.name}"
+	publish = true
+	docker {
+		publishRegistry {
+			username = "user"
+			password = "secret"
+			url = "https://docker.example.com/v1/"
+			email = "user@example.com"
+		}
+	}
+}
+// end::publish[]