Pipeline Parameters (String, Boolean, Choice)

Why Parameters in a Pipeline?

Instead of manually selecting parameters through the GUI every time, we can define them directly in the pipeline code using a parameters block placed right after agent.

• On the first build, Jenkins simply runs the code and registers the parameters.
• After the first build, go to Configure and confirm the parameters were picked up, then Save.
• From the second build onward, use "Build with Parameters" to actually provide values and see the parameter-driven output.
• You typically need to build twice to see the real output the first time.
• When using parameters, you don't need a separate environment block.

String Parameter

pipeline {
    agent any
    parameters {
        string(name: "person", defaultValue: "Sandeep", description: "")
    }
    stages {
        stage('Hello') {
            steps {
                sh 'echo "hi my name is $person"'
            }
        }
    }
}

Boolean Parameter

pipeline {
    agent any
    parameters {
        booleanParam(name: "db", defaultValue: true, description: "")
    }
    stages {
        stage('Hello') {
            steps {
                sh 'echo "hi this is boolean parameters"'
            }
        }
    }
}

If defaultValue is true, the checkbox appears checked (enabled) on the Build with Parameters screen; false leaves it unchecked.

Choice Parameter

pipeline {
    agent any
    parameters {
        choice(name: "file", choices: ["sandeep", "chikkala", "sandy", "bablu"], description: "")
    }
    stages {
        stage('Choice Parameter') {
            steps {
                sh 'echo "touch $file"'
            }
        }
    }
}

On "Build with Parameters" you get a dropdown to pick one of the listed choices, which then feeds into the shell command.