Versioning Flex Applications: Displaying Hudson, Maven, SVN build or revision numbers

Hudson sets the values for the following environment variables:

1. BUILD_NUMBER
2. SVN_REVISION

In order to show the build and revision numbers in the UI, these variables could be written out to a properties file via a maven project's pom.xml file using a plugin. And then if one did this early enough in the maven lifecycle, your flex application could be compiled to read the version information as key-value pairs from the properties file and show the info on screen when it runs.

Alas there is no decent maven plugin out there to write environment variables out to a file. I found the following plugins out there but none of them (+/-) did the trick.

1. org.codehaus.mojo:properties-maven-plugin can be found in the following repo You can find proper documentation here. It never printed anything but the Java system level variables so it was useless when it came to tracking the environment variables set by Hudson.
2. org.sonatype.plugins:maven-properties-plugin can be found in the following repo but this isn't the one you want to use. It has only one goal called filter-file and I cannot find any page documenting its usage no matter how hard I try.
3. Even placing the info generated by the mvn help:system command-line invocation seemed like a decent idea. But after configuring the same command to be invoked inside a pom file(+/-) I realized that it spit out some header lines that weren't commented out in a manner suited for a properties file.
   
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-help-plugin</artifactId>
           <version>2.1.1</version>
           <executions>
             <execution>
               <phase>generate-resources</phase>
               <goals>
                 <goal>system</goal>
               </goals>
               <configuration>
                 <output>${basedir}/src/locale/app.properties</output>
               </configuration>
             </execution>
           </executions>
         </plugin>

You can resort to usind the ant plugin inside Maven to do a macro-style replace technique. You can read more about it here.

Or the best way is to have a template file (+-) and leverage Maven model like this (+-)

<?xml version="1.0" encoding="UTF-8"?>
<root>
<buildNumber>${buildNumber}</buildNumber>
<svnRevisionNumber>${svnRevision}</svnRevisionNumber>
</root>

<project >
  ...
  <!-- Map the values provided by the Hudson build to local variables -->
  <properties>
    <buildNumber>${BUILD_NUMBER}</buildNumber>
    <svnRevision>${SVN_REVISION}</svnRevision>
  </properties>
  ...
  <build>
    ...
    <!-- Update version.xml file with the versioning data -->
    <resources>
      <resource>
        <targetPath>${project.build.directory}/${project.artifactId}-${project.version}</targetPath>
        <filtering>true</filtering>
        <directory>${basedir}/src/main/resources</directory>
        <includes><include>version.xml</include></includes>
      </resource>
    </resources>
    ...
  <build>
  ...
<project >

Also as a sidenote: The Hudson variables can be placed inside the manifest file if your artifact being built happens to be a war or jar file. Read more on that here.

Links:
Home / Using Flex 4 / Developer tools / Flex compilers / Using mxmlc, the application compiler / Passing Strings
How to configure flexmojos to pass in compile time variables:
gmail thread
official docs