Reading file from Workspace in Jenkins with Groovy script

Question

I want to add a Build step with the Groovy plugin to read a file and trigger a build fail depending on the content of the file.

How can I inject the workspace file path in the groovy plugin ?

myFileDirectory = // Get workspace filepath here ???
myFileName = "output.log"
myFile = new File(myFileDirectory + myFileName)

lastLine = myFile.readLines().get(myFile.readLines().size().toInteger() - 1)
if (lastLine ==~ /.Fatal Error.*/ ){
    println "Fatal error found"
    System.exit(1)
} else{
   println "nothing to see here"
}

Answer 1

I realize this question was about creating a plugin, but since the new Jenkins 2 Pipeline builds use Groovy, I found myself here while trying to figure out how to read a file from a workspace in a Pipeline build. So maybe I can help someone like me out in the future.

Turns out it's very easy, there is a readfile step, and I should have rtfm:

env.WORKSPACE = pwd()
def version = readFile "${env.WORKSPACE}/version.txt"