Support podman for building images

Closes gh-30196

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

@@ -16,7 +16,7 @@ The `bootBuildImage` task 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 `bootBuildImage` task to use the https://minikube.sigs.k8s.io/docs/tasks/docker_daemon/[Docker daemon provided by minikube].
+Environment variables can be set to configure the `bootBuildImage` task to use an alternative local or remote connection.
 The following table shows the environment variables and their values:
 
 |===
@@ -32,8 +32,6 @@ The following table shows the environment variables and their values:
 | Path to certificate and key files for HTTPS (required if `DOCKER_TLS_VERIFY=1`, ignored otherwise)
 |===
 
-On Linux and macOS, these environment variables can be set using the command `eval $(minikube docker-env)` after minikube has been started.
-
 Docker daemon connection information can also be provided using `docker` properties in the plugin configuration.
 The following table summarizes the available properties:
 
@@ -416,7 +414,14 @@ include::../gradle/packaging/boot-build-image-caches.gradle.kts[tags=caches]
 [[build-image.examples.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:
+[[build-image.examples.docker.minikube]]
+==== Docker Configuration for minikube
+
+The plugin can communicate with the https://minikube.sigs.k8s.io/docs/tasks/docker_daemon/[Docker daemon provided by minikube] instead of the default local connection.
+
+On Linux and macOS, environment variables can be set using the command `eval $(minikube docker-env)` after minikube has been started.
+
+The plugin can also be configured to use the minikube daemon by providing connection details similar to those shown in the following example:
 
 [source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
 .Groovy
@@ -430,6 +435,28 @@ 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]
 ----
 
+[[build-image.examples.docker.podman]]
+==== Docker Configuration for podman
+
+The plugin can communicate with a https://podman.io/[podman container engine].
+
+The plugin can be configured to use podman local connection by providing connection details similar to those shown in the following example:
+
+[source,groovy,indent=0,subs="verbatim,attributes",role="primary"]
+.Groovy
+----
+include::../gradle/packaging/boot-build-image-docker-host-podman.gradle[tags=docker-host]
+----
+
+[source,kotlin,indent=0,subs="verbatim,attributes",role="secondary"]
+.Kotlin
+----
+include::../gradle/packaging/boot-build-image-docker-host-podman.gradle.kts[tags=docker-host]
+----
+
+[[build-image.examples.docker.auth]]
+==== Docker Configuration for Authentication
+
 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` properties as shown in the following example:
 
 [source,groovy,indent=0,subs="verbatim,attributes",role="primary"]

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/gradle/packaging/boot-build-image-docker-host-podman.gradle

@@ -0,0 +1,24 @@
+plugins {
+	id 'java'
+	id 'org.springframework.boot' version '{gradle-project-version}'
+}
+
+tasks.named("bootJar") {
+	mainClass = 'com.example.ExampleApplication'
+}
+
+// tag::docker-host[]
+tasks.named("bootBuildImage") {
+	docker {
+		host = "unix:///run/user/1000/podman/podman.sock"
+		bindHostToBuilder = true
+	}
+}
+// end::docker-host[]
+
+tasks.register("bootBuildImageDocker") {
+	doFirst {
+		println("host=${tasks.bootBuildImage.docker.host}")
+		println("bindHostToBuilder=${tasks.bootBuildImage.docker.bindHostToBuilder}")
+	}
+}

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

@@ -0,0 +1,27 @@
+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.named<BootJar>("bootJar") {
+	mainClass.set("com.example.ExampleApplication")
+}
+
+// tag::docker-host[]
+tasks.named<BootBuildImage>("bootBuildImage") {
+	docker {
+		host = "unix:///run/user/1000/podman/podman.sock"
+		isBindHostToBuilder = true
+	}
+}
+// end::docker-host[]
+
+tasks.register("bootBuildImageDocker") {
+	doFirst {
+		println("host=${tasks.getByName<BootBuildImage>("bootBuildImage").docker.host}")
+		println("bindHostToBuilder=${tasks.getByName<BootBuildImage>("bootBuildImage").docker.isBindHostToBuilder}")
+	}
+}

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

@@ -12,7 +12,7 @@ tasks.named("bootBuildImage") {
 	docker {
 		host = "tcp://192.168.99.100:2376"
 		tlsVerify = true
-		certPath = "/home/users/.minikube/certs"
+		certPath = "/home/user/.minikube/certs"
 	}
 }
 // end::docker-host[]

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

@@ -15,7 +15,7 @@ tasks.named<BootBuildImage>("bootBuildImage") {
 	docker {
 		host = "tcp://192.168.99.100:2376"
 		isTlsVerify = true
-		certPath = "/home/users/.minikube/certs"
+		certPath = "/home/user/.minikube/certs"
 	}
 }
 // end::docker-host[]

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/docs/PackagingDocumentationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -279,11 +279,19 @@ class PackagingDocumentationTests {
 	}
 
 	@TestTemplate
-	void bootBuildImageWithDockerHost() {
+	void bootBuildImageWithDockerHostMinikube() {
 		BuildResult result = this.gradleBuild.script("src/docs/gradle/packaging/boot-build-image-docker-host")
 				.build("bootBuildImageDocker");
 		assertThat(result.getOutput()).contains("host=tcp://192.168.99.100:2376").contains("tlsVerify=true")
-				.contains("certPath=/home/users/.minikube/certs");
+				.contains("certPath=/home/user/.minikube/certs");
+	}
+
+	@TestTemplate
+	void bootBuildImageWithDockerHostPodman() {
+		BuildResult result = this.gradleBuild.script("src/docs/gradle/packaging/boot-build-image-docker-host-podman")
+				.build("bootBuildImageDocker");
+		assertThat(result.getOutput()).contains("host=unix:///run/user/1000/podman/podman.sock")
+				.contains("bindHostToBuilder=true");
 	}
 
 	@TestTemplate