org.codehaus.mojo:properties-maven-plugin:1.0-alpha-2 error - maven

Question

I have the following Maven project structure:
xyz
|
-props
| |
| - root.properties
|
-module_a
| |
| -pom.xml
|
-pom.xml
My root artifact defines a child module (module_a) and this is referencing the parent artifact.
In the root pom.xml I am reading a property file from the common props folder using the
org.codehaus.mojo:properties-maven-plugin:1.0-alpha-2 plugin.
When I issue the
mvn clean package
command I get the following putput:
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order:
[INFO]
[INFO] my_artifact
[INFO] module_a
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building my_artifact 1.0.0
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-clean-plugin:2.4.1:clean (default-clean) # my_artifact ---
[INFO]
[INFO] --- properties-maven-plugin:1.0-alpha-2:read-project-properties (default) # my_artifact ---
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building module_a 1.0.0
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-clean-plugin:2.4.1:clean (default-clean) # module_a ---
[INFO]
[INFO] --- properties-maven-plugin:1.0-alpha-2:read-project-properties (default) # module_a ---
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] my_artifact ....................................... SUCCESS [0.234s]
[INFO] module_a .......................................... FAILURE [0.000s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.344s
[INFO] Finished at: Thu Aug 09 15:37:46 CEST 2012
[INFO] Final Memory: 2M/5M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:properties-maven-plugin:1.0-alpha-2:read-project-properties (default) on project module_a: Properties file not found: G:\java\xyz\module_a\props\root.properties -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
[ERROR]
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR] mvn <goals> -rf :module_a
In the child module Maven tries to read the property file from an inexistetnt subfolder. Can anybody help me solve this?
Thank you

Answer 1

When maven evaluates the pom files and creates the effective poms ( aggregated with inheritance) some properties are excluded from being inherited. These are the ones starting with project.* and therefore also the project.basedir. Thats why you cannot define the property from where the property file is being loaded in the parent.
The reason for this behaviour is isolation. Every module should be isolated from everything but the maven repository. Even using the settings.xml profiles violates this invariant and you loose the portability of builds.
This invariant is not necessary in many cases so if you have many modules and you want to use one property file, what you can do is:
define a property e.g. "filters.dir" in your root pom to ${project.basedir}/src/main/filters
configure the plugin to load a property file from ${filters.dir}/my.properties
in any submodule you can now override filters.dir to ../src/main/filters
if you have many submodules you can define a wrong path "../src/main/filters" for filters.dir in the root and then you don't need to define the property in any submodule. To prevent the build from failing you need to set the plugin to ignore failures.
An alternative would be to write a maven extension by extending AbstractMavenLifecycleParticipant and load the property file there using the maven api to determine the root directory of your project.

Answer 2

I have face a similar issue.
I have a parent project pom.xml which has a build.properties file
the parent project has several modules.
When I created a new module, and wanted to build the whole parent project, I got:
[ERROR] Failed to execute goal org.codehaus.mojo:properties-maven-plugin:1.0-alpha-2:read-project-properties (default) on project attachment-services: Properties file not found: /home/raz/git/parent/attachment-services/build.properties -> [Help 1]
To fix this, I have added in the new module's pom.xml the following
<properties>
<build.properties.location>..</build.properties.location>
</properties>
and of course, this build.properties.location was already defined in the parent pom, like:
<properties>
<build.properties.location>${project.basedir</build.properties.location
</properties>