Fix Buildx build with Dockerfile outside of Docker build context

doc/changelog.md

@@ -2,6 +2,7 @@
 * **0.44-SNAPSHOT**:
   - Add new option "useDefaultExclusion" for build configuration to handle exclusion of hidden files ([1708](https://github.com/fabric8io/docker-maven-plugin/issues/1708))
   - The <noCache> option is now propagated down to the buildx command, if it is set in the <build> section. ([1717](https://github.com/fabric8io/docker-maven-plugin/pull/1717))
+  - Fix Buildx build with Dockerfile outside of the Docker build context directory ([1721](https://github.com/fabric8io/docker-maven-plugin/pull/1721))
 
 * **0.43.4** (2023-08-18):
   - Always pass `--config` option for latest versions of Docker CLI ([1701](https://github.com/fabric8io/docker-maven-plugin/issues/1701))

it/buildx-dockerfile_and_contextdir/Dockerfile

@@ -0,0 +1,4 @@
+FROM debian:bullseye-slim
+
+COPY resource.properties /
+CMD [ "echo", "Hello World" ]

it/buildx-dockerfile_and_contextdir/pom.xml

@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <parent>
+    <groupId>io.fabric8.dmp.itests</groupId>
+    <artifactId>dmp-it-parent</artifactId>
+    <version>0.44-SNAPSHOT</version>
+    <relativePath>../pom.xml</relativePath>
+  </parent>
+
+  <artifactId>dmp-it-buildx-dockerfile_and_contextdir</artifactId>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>io.fabric8</groupId>
+        <artifactId>docker-maven-plugin</artifactId>
+        <configuration>
+          <outputDirectory>target/docker-build</outputDirectory>
+          <useColor>false</useColor>
+          <verbose>all</verbose>
+          <images>
+            <image>
+              <name>${project.artifactId}:${project.version}</name>
+              <build>
+                <dockerFile>${project.basedir}/Dockerfile</dockerFile>
+                <contextDir>${project.basedir}/src/docker</contextDir>
+                <buildx>
+                  <platforms>
+                    <platform>linux/amd64</platform>
+                    <platform>linux/arm64</platform>
+                  </platforms>
+                </buildx>
+              </build>
+            </image>
+          </images>
+        </configuration>
+        <executions>
+          <execution>
+            <id>default</id>
+            <goals>
+              <goal>build</goal>
+            </goals>
+            <phase>package</phase>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

it/buildx-dockerfile_and_contextdir/src/docker/resource.properties

@@ -0,0 +1,2 @@
+name=value1
+key=value2

it/pom.xml

@@ -25,6 +25,7 @@
     <module>buildx-contextdir</module>
     <module>buildx-dependencyset</module>
     <module>buildx-dockerfile</module>
+    <module>buildx-dockerfile_and_contextdir</module>
     <module>buildx-push</module>
     <module>docker-compose</module>
     <module>dockerfile</module>

src/main/java/io/fabric8/maven/docker/service/BuildXService.java

@@ -204,8 +204,8 @@ protected void buildX(List<String> buildX, String builderName, BuildDirs buildDi
         File contextDir = buildConfiguration.getContextDir();
         if (contextDir != null) {
             Path destinationPath = getContextPath(buildArchive);
-            Path dockerFileRelativePath = contextDir.toPath().relativize(buildConfiguration.getDockerFile().toPath());
-            append(cmdLine, "--file=" + destinationPath.resolve(dockerFileRelativePath), destinationPath.toString());
+            String dockerFileName = buildConfiguration.getDockerFile().getName();
+            append(cmdLine, "--file=" + destinationPath.resolve(dockerFileName), destinationPath.toString());
         } else {
             cmdLine.add(buildDirs.getOutputDirectory().getAbsolutePath());
         }