how to fail maven build on dependency conflict - maven-2

Question

Im working on a large multi-module project which uses an internal framework as one of its dependencies. The framework version is set in the top level pom at the beginning of a project, and has to stay constant. If any submodule uses a different version, I want the build to fail.
Ive tried declaring the dependency as a single version:
<dependency>
<groupId>framework_snt</groupId>
<artifactId>SFP</artifactId>
<version>[6.1]</version>
<type>pom</type>
</dependency>
Ive tried using the enforcer plugin with banned dependencies:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-enforcer-plugin</artifactId>
<version>1.0.1</version>
<executions>
<execution>
<id>enforce-versions</id>
<goals>
<goal>enforce</goal>
</goals>
<configuration>
<rules>
<requireJavaVersion>
<version>[1.6.0-21]</version>
</requireJavaVersion>
<requireMavenVersion>
<version>[3.0.3]</version>
</requireMavenVersion>
<bannedDependencies>
<excludes>
<exclude>framework_snt:SFP</exclude>
</excludes>
<includes>
<include>framework_snt:SFP:6.1.2</include>
</includes>
</bannedDependencies>
</rules>
</configuration>
</execution>
</executions>
</plugin>
Ive also tried adding the <DependencyConvergence/> tag as mentioned here, but none of these approaches work.
So given this top level pom fragment:
<project>
<groupId>glb</groupId>
<artifactId>GLB</artifactId>
<packaging>pom</packaging>
<name>Global</name>
<version>1.0</version>
........
<dependencies>
<dependency>
<groupId>framework_snt</groupId>
<artifactId>SFP</artifactId>
<version>[6.1.2]</version>
<type>pom</type>
</dependency>
</dependencies>
.....
</project>
And this (invalid) submmodule:
<project>
<groupId>glb</groupId>
<artifactId>CORE</artifactId>
<packaging>jar</packaging>
<name>Core</name>
<version>1.0</version>
<parent>
<groupId>glb</groupId>
<artifactId>GLB</artifactId>
<version>1.0</version>
</parent>
<dependencies>
<dependency>
<groupId>framework_snt</groupId>
<artifactId>SFP</artifactId>
<version>6.3</version>
<type>pom</type>
</dependency>
</dependencies>
</project>
how do I setup maven so the build will fail when using the child module above, but when I remove the tag <version>6.3</version> it succeeds (or I change the version to match the one from the top level pom?

Answer 1

Well after much search and trying stuff with various plugins and getting nowhere, I decided to write my own plugin to do conflict checking. Using the dependency:tree plugin source as a base I wrote the following:
/**
* Walks the dependency tree looking for anything marked as a conflict, and fails the build if one is found
* code ripped from the dependency:tree plugin
*
* #param rootNode
* the dependency tree root node to check
*
*/
private void checkForConflicts( DependencyNode rootNode ) throws MojoExecutionException
{
StringWriter writer = new StringWriter();
boolean conflicts=false;
// build the tree
DependencyNodeVisitor visitor = new SerializingDependencyNodeVisitor( writer, SerializingDependencyNodeVisitor.STANDARD_TOKENS);
visitor = new BuildingDependencyNodeVisitor( visitor );
rootNode.accept( visitor );
getLog().debug("Root: "+rootNode.toNodeString() );
DependencyNode node;
Artifact actual, conflict;
DependencyTreeInverseIterator iter = new DependencyTreeInverseIterator(rootNode);
while (iter.hasNext() )
{
node = (DependencyNode)iter.next();
if (node.getState() == DependencyNode.OMITTED_FOR_CONFLICT)
{
actual = node.getArtifact();
conflict = node.getRelatedArtifact();
getLog().debug("conflict node: " + node.toNodeString() );
getLog().debug("conflict with: "+conflict.toString() );
getLog().error(actual.getGroupId()+":"+actual.getArtifactId()+":"+actual.getType()+" Conflicting versions: "+actual.getVersion()+" and "+conflict.getVersion() );
conflicts=true;
}
}
if (conflicts)
throw new MojoExecutionException( "version conflict detected");
}
You can call this from your existing plugin using the following:
try
{
rootNode = dependencyTreeBuilder.buildDependencyTree( project, localRepository, artifactFactory, artifactMetadataSource, null, artifactCollector );
checkForConflicts( rootNode );
}
catch ( DependencyTreeBuilderException e)
{
throw new MojoExecutionException( "Cannot build project dependency tree", e);
}
Then in your plugin pom.xml, include dependencies from the existing dependency plugin source and your good to go.
This works for our project -- but if anyone knows a cleaner or better way, please let me know.