How to determine Jenkins build directory from Ant? - ant

Question

I am trying to migrate an Ant script I wrote to build and deploy projects from within the Jenkins framework (instead of triggered from an SVN post-commit hook, which was the expedient way we initially approached things). Everything is great, except I need to stage files for the deploy step and I want to stuff them into the 'build' directory Jenkins creates for the job (and since my build.xml lives in a non-project-specific location, ${basedir} and ${user.dir} do not point to the desired location).
within the Jenkins configuration, I've setup the following:
[Jenkins]
Build Record Root Directory: E:/builds/${ITEM_FULLNAME}
[Job-Specific]
Build File: C:\vc-tools\shadow\build.xml
when running a build, the script is appropriately launched and a job-specific build directory is created, e.g.
E:\builds\Test\2012-08-07_12-51-21
I want to get at this directory from within the build script, but cannot figure out how. some of the things I've tried:
[echo] ${basedir}: C:\vc-tools\shadow
[echo] ${user.dir}: C:\vc-tools
[echo] ${env.workspace}: C:\Program Files (x86)\Jenkins\workspace\Test
[echo] ${env.build_id}: 2012-08-07_12-51-21
[echo] ${jenkins_home}: C:\Program Files (x86)\Jenkins
[echo] ${BuildDir}: E:/builds/${ITEM_FULLNAME}
note: for that last one, I tried passing in:
BuildDir=E:/builds/${ITEM_FULLNAME}
as a property configured from the job within Jenkins (clearly ${} expansion doesn't take place in this context).
according to the documentation, there are no specific environment variables that are set to the full build directory path -- I can fudge it by hardcoding the E:\builds root and tacking on ${env.build_id}, but was hoping there would be an easier way to access the complete path from something Jenkins exposes (either an Ant property and an environment variable) in order to make the script more flexible.
I am using Jenkins version 1.476.
thanks

Answer 1

It's always a good idea for your project to have a copy of it's build logic included alongside the source code. It makes your build more portable across machines.
Having said that it's also quite common to setup build files containing common shared build logic. ANT defines the following tasks to support such activity:
include
import
So a possible solution is to store a simple build.xml file, in the root of your project directory:
<project name="my project" default="build">
<include file="C:\vc-tools\shadow\common-build-1.0.xml" as="common"/>
<target name="build" depends="common.build"/>
</project>
Notes:
It's a good idea to use a revision number in the common build file name. This assists in preserving backward compatibility with other builds using the older logic.
Update
When Jenkins runs a job is sets a number of environment variables.
The following ANT logic will print the location of the Jenkins workspace directory:
<property environment="env"/>
<target name="run">
<echo message="Jenkins workspace: ${env.WORKSPACE}"/>
<echo message="Job directory: ${env.WORKSPACE}../../jobs/${env.JOB_NAME}"/>
<echo message="Build data: ${env.WORKSPACE}../../jobs/${env.JOB_NAME}/build/${env.BUILD_ID}"/>
</target>

Answer 2

These days (Jenkins v. 1.484) 'run' target from answer above should look like this:
<target name="run">
<echo message="Jenkins workspace: ${env.WORKSPACE}"/>
<echo message="Job directory: ${env.WORKSPACE}/../../${env.JOB_NAME}"/>
<echo message="Build data: ${env.WORKSPACE}/../../${env.JOB_NAME}/builds/${env.BUILD_ID}"/>
</target>