Plugin fails when running with maven using remote build cache

[warmuuh]

Environment:

• Jib version: 3.4.4
• Build tool: maven 3.9.9
• OS: linux/macos

Description of the issue:
when using the maven remote build cache, the plugin fails to build the jib, either failing with

Obtaining project build output files failed; make sure you have compiled your project before trying to build the image. (Did you accidentally run "mvn clean jib:build" instead of "mvn clean compile jib:build"?)

or when running using <containerizingMode>packaged</containerizingMode>

Failed to execute goal com.google.cloud.tools:jib-maven-plugin:3.4.4:dockerBuild (default) on project xxx: .../target/classes is not a directory

Expected behavior:
I understand that the plugin is relying on the compiled classes to exist when running in containerizingMode=exploded, but the packaged containerizingMode should (as far as i understood) use the existing jar file instead (which is the only thing existing when using a remote build cache)

Steps to reproduce:

1. setup a maven project with jib configured and maven build cache extension
2. run mvn clean package twice (second time for cache hit)
3. error

jib-maven-plugin Configuration:

<plugin>
        <groupId>com.google.cloud.tools</groupId>
        <artifactId>jib-maven-plugin</artifactId>
        <configuration>
          <skip>false</skip>
          <from>
            <image>gcr.io/distroless/java21-debian12:nonroot</image>
          </from>
          <containerizingMode>packaged</containerizingMode>
          <to>
            <!-- TODO: this image is being pushed to the registry for each build, do we need it there? -->
            <image>...</image>
          </to>
          <container>
            <ports>
              <port>50051</port>
            </ports>
          </container>
        </configuration>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>dockerBuild</goal>
            </goals>
          </execution>
        </executions>
      </plugin>

Log output:

Failed to execute goal com.google.cloud.tools:jib-maven-plugin:3.4.4:dockerBuild (default) on project xxx: .../target/classes is not a directory

Additional Information:

• when running maven using a remote cache build, there is no target/classes directory, but a target/<finalName>-<version>.jar file

[diegomarquezp]

Hi @warmuuh, what is the maven command you were running to reproduce this issue? Also and if possible, could you share your project structure as well?