Final-keyword doesn't work properly in Pipeline

Using Jenkins
1

I want to use a constant in my pipeline:

pipeline {
    agent any

    stages {
        stage('Hello') {
            steps {
                script {
                    final String str = "someVal"
                    str = "yetAnotherVal" // Exception expected
                    echo str
                }
            }
        }
    }
}

But this pipeline is executed successfully, I get output in stdout: “yetAnotherVal”

I went ahead and simply ran the following code in Main Pipeline Script via Replay:

final String str = "someVal"
str = "yetAnotherVal" // Exception expected
println str

The result is the same

Is this related to Jenkins using Groovy 2.4.21?

I assume so, because Groovy 2.4.21 also has this behavior:

ilyait@DESKTOP-H4GIJH3:/mnt/c/Users/ilya/Documents$ cat main.groovy
final String str = "someVal"
str = "1"
println str
ilyait@DESKTOP-H4GIJH3:/mnt/c/Users/ilya/Documents$ ./groovy-2.4.21/bin/groovy main.groovy
1

This is fixed in Groovy 2.5.10:

ilyait@DESKTOP-H4GIJH3:/mnt/c/Users/ilya/Documents$ ./groovy-2.5.10/bin/groovy main.groovy
org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
/mnt/c/Users/ilya/Documents/main.groovy: 2: The variable [str] is declared final but is reassigned
. At [2:1]  @ line 2, column 1.
   str = "1"
   ^

1 error

If this is indeed related to an outdated version of Groovy, what stage is this issue at now?

My Jenkins setup:

Jenkins: 2.492.2
OS: Linux - 5.15.167.4-microsoft-standard-WSL2
Java: 17.0.14 - Eclipse Adoptium (OpenJDK 64-Bit Server VM)
installed-plugins.log (2.9 KB)

2

Yes, you are most likely hitting this because Jenkins is using a version of Groovy that doesn’t work for final in the way you are expecting. Updating Groovy is a HUGE undertaking, that I am not sure is on the roadmap yet, but I could be wrong.

3

Thanks for the reply!)

Can the community help advance this complex task? If there are open issues I would be happy to see what I can do

4

https://issues.jenkins.io/browse/JENKINS-53372 is the first ticket for upgrading from 2.4 to 2.5
The biggest problem seems to be the sandboxing done in Jenkins

5

Updating Groovy would not likely fix this. Pipeline script is run through a Jenkins-specific transformer which winds up essentially running an independent interpreter, and I suppose nobody bothered to check for the final modifier in this context. Just pretend the modifier does not exist and do not assign another value.