How to set and reference a variable in a Jenkinsfile

Question

I have a declarative pipeline script for my multibranch project in which I would like to read a text file and store the result as a string variable to be accessed by a later step in the pipeline. Using the snippet generator I tried to do something like this:

filename = readFile 'output.txt'

For which filename would be my string.

I get an error in the Jenkins console output:

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
WorkflowScript: 30: Expected a step @ line 30, column 5.
            filename = readFile 'output.txt'

Do I need to use a withEnv step to set the output of readFile to a Jenkins environment variable? If so, how?

Thanks

Answer 1

The error is due to that you're only allowed to use pipeline steps inside the steps directive. One workaround that I know is to use the script step and wrap arbitrary pipeline script inside of it and save the result in the environment variable so that it can be used later.

So in your case:

pipeline {
    agent any
    stages {
        stage("foo") {
            steps {
                script {
                    env.FILENAME = readFile 'output.txt'
                }
                echo "${env.FILENAME}"
            }
        }
    }
}