How to pass a variable in Jenkins Credentials Helper Function

Question

 environment {
    BRANCH_NAME = "${env.BRANCH_NAME}"
    DEPLOYMENT_MACHINE = credentials('auto-deployment')
}

How to pass Variable to credentials Function like

environment {
    BRANCH_NAME = "${env.BRANCH_NAME}"
    DEPLOYMENT_MACHINE = credentials("${BRANCH_NAME}")
}

Answer 1

"${exp}" is Groovy String interpolation, it is an alternative to "" + exp + "".

thus you can simply do

def deploymentBranchCred = credential(env.BRANCH_NAME)

Answer 2

 environment {    
    DEPLOYMENT_MACHINE = credentials("${env.BRANCH_NAME}")
    BRANCH = "${env.BRANCH_NAME}"
}

It's Working Fine.! issue with BRANCH_NAME as declared again in the environment.