How to use a single checkstyle suppression file in Maven for all modules.

Question

I have a project that consists of several Maven modules which are all children of a parent module. I have the parent set up to use checkstyle and the child modules all inherit this behaviour correctly. I would like all the child modules to use the parents suppression file defined in its plugin. I define a property checkstyle.suppression which is used in the checkstyle plugin

<properties>
  <checkstyle.suppressions>${basedir}\src\checkstyle\suppressions.xml</checkstyle.suppressions>
</properties>

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-checkstyle-plugin</artifactId>
    <version>2.2</version>
    <configuration>
      <configLocation>config/sun_checks.xml</configLocation>
      <suppressionsLocation>${checkstyle.suppressions}</suppressionsLocation>
      <suppressionsFileExpression>${checkstyle.suppressions}</suppressionsFileExpression>
    </configuration>
  </plugin>
</plugins>

Which works fine for the parent but all the child modules try to find the file in their basedir which does make sense.
I am sure there must be a simple solution I am missing but is there a way to define this location so that all the child modules will use the parent location without hard coding it?

Answer 1

Have you tried defining the property like this in the parent pom or redefining it in the childrens?

 <properties>
   <checkstyle.suppressions>${parent.project.basedir}\src\checkstyle\suppressions.xml</checkstyle.suppressions>
 </properties>

Answer 2

If the parent isn't going to run checkstyle, you might just be able to rewrite it to

<properties>
  <checkstyle.suppressions>..\..\src\checkstyle\suppressions.xml</checkstyle.suppressions>
</properties>

Or something like this. Or you could put something in settings.xml to point everything to an system wide config directory.

While it might not be recommended, you can have use a boot-strap or set-up project or task put a copy of the suppressions.xml file to a location specified by a property in settings.xml and then always refer to it by that locations.

Answer 3

The plugin's documentation mentions a similar use case here: http://maven.apache.org/plugins/maven-checkstyle-plugin/examples/multi-module-config.html

Answer 4

The answers above are dangerous. I maintain that each project should be self contained, so referring to files external to it is going to break a build sooner or later. Checkstyle can take a url for the file but that means you can't build offline. A better approach is to package your file (can also add pmd.xml) into a jar and then add that jar to the classpath of the checkstyle (or pmd) plugin. I have an example of it here and more about overridding a plugin classpath here