Maven Version Housekeeping

It is inevitable. In any project of a certain size, after a while, you are faced with the challenge of rotting dependencies. To be more precise, the world has moved on and you, for whatever reason, want to keep up.

Step 1 - Figure out what has changed

Fortunately, Maven has a set of tools for figuring out which dependencies have changed. The plugin we'll be using is the versions-maven-plugin

The goal that helps us is the display-dependency-updates. Just run the following in your project:

mvn versions:display-dependency-updates

In the following I will use the maven-surefire-plugin source code as an example.

Step 2 - Unix to the resque

In a multi-module project, the versions-plugin will generate tons of text. The information you are after is buried in a verbose black hole. Most likely, several of your dependencies are the same across multiple modules. How do you sift through all this information?

One option is to break out your text editor and spend 15 minutes deleting text by hand until you find what you need. This process must be repeated manually the next time you want to check for new versions.

As fun as that sounds, we are lazy and automate. If you are ever faced with the task to handle large amounts of text, always try the Unix toolbox first. Chances are you will find what you need.

First, we make sure all version information is on one line. The excerpt below illustrates the problem. The dependency name is too long, making the version output break the line.

[INFO]   org.apache.maven.plugin-testing:maven-plugin-testing-harness ...
[INFO]                                                               1.2 -> 2.1

I chose to solve this with sed (GNU sed), but tr or awk would do the same use.

sed -r ':a;N;$!ba;s/\s+(\.\.\.){1}\n(\[INFO\]){1}\s+/ /g'

Second, we get rid of the redundancy with uniq. Uniq requires its input to be sorted as it only compares adjacent lines for similarity. Thus we pipe the output to sort first.

Finally, we only care about what has actually changed. Grep will filter out any line that does not contain an arrow, '->'.

The final command is thus:

mvn versions:display-dependency-updates 
| gsed -r ':a;N;$!ba;s/\s+(\.\.\.){1}\n(\[INFO\]){1}\s+/ /g'
| sort | uniq 
| grep '.*->'

The result is an output that is exactly what we need, no more.

[INFO]   commons-io:commons-io ................................... 2.0.1 -> 2.4
[INFO]   jmock:jmock ................................. 1.0.1 -> 20031129.200437
[INFO]   junit:junit ............................................ 3.8.1 -> 4.11
[INFO]   junit:junit ............................................ 3.8.2 -> 4.11
[INFO]   junit:junit ............................................ 4.8.1 -> 4.11
[INFO]   junit:junit ............................................. 4.10 -> 4.11
[INFO]   junit:junit .............................................. 4.0 -> 4.11
[INFO]   net.sourceforge.htmlunit:htmlunit ........................ 2.8 -> 2.11
[INFO]   org.apache.maven.doxia:doxia-core ....................... 1.1.4 -> 1.3
[INFO]   org.apache.maven.doxia:doxia-decoration-model ........... 1.1.4 -> 1.3
[INFO]   org.apache.maven.doxia:doxia-sink-api ................... 1.1.4 -> 1.3
[INFO]   org.apache.maven.doxia:doxia-site-renderer .............. 1.1.4 -> 1.3
[INFO]   org.apache.maven.plugin-testing:maven-plugin-testing-harness 1.2 -> 2.1
[INFO]   org.apache.maven.reporting:maven-reporting-api .......... 2.0.9 -> 3.0
[INFO]   org.apache.maven.reporting:maven-reporting-impl ........... 2.1 -> 2.2
[INFO]   org.apache.maven.shared:maven-common-artifact-filters ..... 1.3 -> 1.4
[INFO]   org.apache.maven.surefire:surefire-api ................ 2.12.4 -> 2.13
[INFO]   org.apache.maven.surefire:surefire-booter ............. 2.12.4 -> 2.13
[INFO]   org.apache.maven.surefire:surefire-junit3 ............. 2.12.4 -> 2.13
[INFO]   org.apache.maven:maven-artifact ....................... 2.0.9 -> 3.0.5
[INFO]   org.apache.maven:maven-artifact ......................... 2.0 -> 3.0.5
[INFO]   org.apache.maven:maven-core ........................... 2.0.9 -> 3.0.5
[INFO]   org.apache.maven:maven-model .......................... 2.0.9 -> 3.0.5
[INFO]   org.apache.maven:maven-plugin-api ..................... 2.0.9 -> 3.0.5
[INFO]   org.apache.maven:maven-plugin-descriptor .............. 2.0.9 -> 2.2.1
[INFO]   org.apache.maven:maven-project .................. 2.0.9 -> 3.0-alpha-2
[INFO]   org.apache.maven:maven-settings ....................... 2.0.6 -> 3.0.5
[INFO]   org.apache.maven:maven-toolchain ................ 2.0.9 -> 3.0-alpha-2
[INFO]   org.codehaus.plexus:plexus-utils ..................... 3.0.8 -> 3.0.10
[INFO]   org.mockito:mockito-all ................................. 1.7 -> 1.9.5
[INFO]   org.testng:testng ......................................... 5.7 -> 6.8