Jenkins: How to use a variable from a pre-build shell in the Maven “Goals and options”

Question

I have a Maven job in Jenkins. Before the actual build step I have an \"Execute shell\" pre-build step. In that shell I set a variable:

REVISION=$(cat .build         


        

Answer 1

I see there is an accepted answer, but for a newbie in Jenkins I found it hard to grasp it all. That's why I would add a bit more detail in this answer and show how I did it.

As @jjungnickel suggested you need to have EnvInject Plugin installed for Jenkins. Then in the Build section > Add build step you'll get option "Inject environment variables".

Basically the idea is:

1. Add variables you want to access later to a file (might be added by a shell script or it could be file from the file system).
2. Inject the file with the variables.
3. Use the variables.

Here a sample setup:

Since I want to use them in maven goal I need to check the Inject Build Variables checkbox.

Then at the end of the build I remove the file just because I want to keep the environment as it was before the build.

Answer 2

I needed to resolve the variables before the injection was done so I put this in script content:

Example: (note it doesn't seem possible to simply export variables here so I wrote to files and the help section in jenkins seems to indicate this is expected)

git ls-tree --name-only -r ${sha1} | grep -v -c "*\.md" > diff.bak

git diff origin/master --shortstat | grep "1 files changed" && echo 1 > count.bak || echo 0 > count.bak

I then added this in the groovy script, using the output files I can create a map:

def procDiff = "cat $WORKSPACE/diff.bak".execute()
def procCount = "cat $WORKSPACE/count.bak".execute()
def diff = procDiff.text
def count = procCount.text

print "string val = $diff and count = $count "

if ("0".equals(diff) || !"1".equals(count)){
def map = ["GOAL": "clean verify"]
return map
} else {
def map = ["GOAL": "clean"]
return map
}

Then I could reference $GOAL in my maven build to conditionally trigger a "clean" or a "clean verify" based on the type of PR raised.

Answer 3

This issue is caused by a bug in the Jenkins Maven Project Plugin as detailed in this bug report opened on 2012-06-22. The plugin has not yet been fixed as of version 2.1.

A fix has been proposed for the Maven Project Plugin, but has not yet been integrated. Here is the link to the pull request: https://github.com/jenkinsci/maven-plugin/pull/14

If you build the plugin yourself with the pull request patch applied, the variables are injected and made available to the "goals and options" field as expected.

Answer 4

I think your best shot is to try the EnvInject plugin for this along with your initial pre-scm step.

1. You run the pre-scm as you already do.
2. You use the env inject to load the file for the main job's build steps

Consider loading your file's content (properties format) or execute a script which will load the file as you want and make a variable available for the rest of the job with the "Prepare an environment for the run" option.

I hope this helps.

Answer 5

You're on the right track here, but missed a third feature of the EnvInject-Plugin: The "Inject environment variables" build step that can inject variables into following build steps based on the result of a script or properties.

We're using the EnvInject plugin just like that; A script sets up a resource and communicates its parameters using properties that are then propagated by the plugin as environment variables.

i.e. setting up a temporary database for the build:

Answer 6

I had a very similar problem, trying to compute a build version and inject it into the build. After running into all the same issues (not expanding, etc), I used the "Generate environment variables from script" option, which interprets the output as tag=value pairs into Jenkins variables. The script :

  #generate a version code that is high enough to surpass previously published clients
  val=`expr 150000 + $BUILD_NUMBER`
  echo VERSION_CODE=$val

After this, I was able to inject $VERSION_CODE into maven as follows :

  -Dbuild.vercode=${VERSION_CODE}

Hope that works for you.