[MNG-5694] Maven shade plugin transformers are not overrideable in child pom.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Auto Closed
• Affects Version/s: 2.2.1
• Component/s: Bootstrap & Build, POM
• Environment: Windows 7, java 1.7.0_60, maven 2.2.1
• Assignee: Unassigned
• Reporter: Kurt Verduyckt
• Created: 26/Sep/14 06:01
• Updated: 16/Mar/18 22:39
• Resolved: 16/Mar/18 22:39

Description

When you configure the maven-shade-plugin with a list of transformers in a root pom, but override the <transformers> section of the maven-shade-plugin in a child pom, the last defined transformer gets all of the parameters of the previous transformers in the list, potentially making mvn install/package unusable.

Concrete case (see also attached zip example) : in the root pom.xml I put the following build configuration with a shade plugin and some transformers :

<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>1.5</version>
<configuration>
<outputFile>test-deploy.jar</outputFile>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.handlers</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.IncludeResourceTransformer">
<file>${project.build.directory}/generated-resources/versions/META-INF/${project.groupId}/${project.artifactId}.version</file>
<resource>META-INF/assembly.version</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>${mainClass}</mainClass>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer" />
</transformers>
</configuration>
</plugin>
</plugins>
</build>

if in a child pom.xml, I now put the exact same transformers (useless override, I know, but sometimes you need to add one in a sub project) :

<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
<configuration>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.handlers</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.IncludeResourceTransformer">
<file>${project.build.directory}/generated-resources/versions/META-INF/${project.groupId}/${project.artifactId}.version</file>
<resource>META-INF/assembly.version</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>${mainClass}</mainClass>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer" />
</transformers>
</configuration>
</plugin>
</plugins>
</build>

the 'mvn install' or 'mvn package' will fail with the following message :

[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Failed to configure plugin parameters for: org.apache.maven.plugins:maven-shade-plugin:1.5

Cause: Cannot find setter nor field in org.apache.maven.plugins.shade.resource.ServicesResourceTransformer for 'resource'
[INFO] ------------------------------------------------------------------------

This is because if you check the effective pom with 'mvn help:effective-pom' you will see that the last transformer also gets the resource, file and mainClass parameters of the transformers defined above, while it's not supposed to:

<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.handlers</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.IncludeResourceTransformer">
<file>D:\dev\issue\child\target/generated-resources/versions/META-INF/mvn.transformers.issue.example/child.version</file>
<resource>META-INF/assembly.version</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>${mainClass}</mainClass>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer">
<resource>META-INF/spring.handlers</resource>
<file>D:\dev\issue\child\target/generated-resources/versions/META-INF/mvn.transformers.issue.example/child.version</file>
<mainClass>${mainClass}</mainClass>
</transformer>
</transformers>

I put this issue in the POM/Bootstrap & Build category because it looks like a general xml 'aggregation' issue (title could maybe be generalized).

Note: this is issue is not present with Maven 3.3.2! But if you do need to use 2.2.1 in your corporate environment, the only solution is to write a dummy transformer yourself that accepts the unwanted parameters to put at the end of the transformers list.