Day: February 8, 2016

Categories
Uncategorized

Maven Irritation

I’m looking at Maven related stuff for the first time in … perhaps 4 years. This is long enough that I’ve forgotten how irritating it is. My task is simple: redirect the writes from the project’s directory to another location on local disk. This is because the project is located on a filesystem where writes are expensive (something like an NFS filer, but worse). I have to do this for all projects, not just my own, so saying “edit the POM to do X” is not an option. Given how disparate the projects are, there isn’t even a company-wide POM I can alter.

Of course the maven documentation tells you everything you don’t want to know. So, off to stack overflow.

First, is the helpful description of ${project.build.directory}. This is exactly what I want: a way to affect all settings related to the output directory (target by default). See pom-4.0.0.xml for how this works.

Except… it doesn’t work. You can set -Dproject.build.directory=/tmp on the command line, and maven will happily ignore you. I think this is because AbstractCompilerMojo marks it as read-only.

It turns out there’s another way to do this, via profiles.

<profile>
  <id>move-output-dir</id>
  <activation>
    <activeByDefault>true</activeByDefault>
  </activation>
  <build>
    <directory>${java.io.tmpdir}/maven-builds/${project.groupId}/${project.artifactId}/target</directory>
  </build>
</profile>

This works perfectly! But it has to be done on a pom-by-pom basis. What I want is to use maven’s settings.xml to do this. So I pasted it into the profile section there and got:

[WARNING] Some problems were encountered while building the effective settings
[WARNING] Unrecognised tag: ‘build’ (position: START_TAG seen …n … @263:14) @ /…/conf/settings.xml, line 263, column 14

It turns out that profiles in settings.xml are different to profiles in pom.xml (“The profile element in the settings.xml is a truncated version of the pom.xml profile element.”)

At this point, I’m kind of stuck. Maven has provided the illusion of configurability, but all attempts to do so have failed.