Jenkins Parallel Nodes execution

jenkins-pipeline-parallel.groovy

def nodeSpecs(List specs, Closure callback) {
    def nodes = [:]
    for (item in specs) {
        def spec = item
        nodes["Spec ${spec}"] = { callback.call(spec) }
    }
    
    return nodes
}

stage("Run Unit Tests") {
    
    parallel nodeSpecs([
        [phpVersion: '5.6', symfonyVersion: '2.3'],
        [phpVersion: '7.1', symfonyVersion: '3.3'],
    ]) { spec -> 
        node('docker') {
            
            stage("Cleaning Workspace") {
                deleteDir()
            }

            stage("Unit Tests for PHP ${spec.phpVersion}, Symfony ${spec.symfonyVersion}") {
                docker.image("php:${spec.phpVersion}-alpine").inside {
                    sh "echo ${spec.phpVersion}"
                    sh "php -r 'print \"Hello ${spec.phpVersion}\" . PHP_EOL;'"
                }
            }
            
        }
    }
}