podTemplate(label: 'mypod', containers: [
    containerTemplate(name: 'maven', image: 'maven:3.3.9-jdk-8-alpine', ttyEnabled: true, command: 'cat'),
  ]) {

    node('mypod') {
        stage('Get a Maven project') {
            withEnv(["SOME_VAR=someval"]) {
//prints
                echo "double quote - ${SOME_VAR}"
//prints literal SOMEVAR
                echo 'single quote - single ${SOME_VAR}'
            }
            container('maven') {
                stage('Build a Maven project') {
                 withEnv(["SOME_VAR=someval"]) {
//same
                    echo "double quote -${SOME_VAR}" 
                    echo 'single quote - ${SOME_VAR}'
                }
                }
            }
        }
    }
  }

pipeline {
  agent {
    kubernetes {
      //cloud 'kubernetes'
      label 'mypod'
      containerTemplate {
        name 'maven'
        image 'maven:3.3.9-jdk-8-alpine'
        ttyEnabled true
        command 'cat'
      }
    }
  }
  
    environment {
        TEST_VAR = 'TEST_VALUE'
    }

    stages {
        stage('JNLP env') {
            steps {
                echo 'Environment variables in JNLP:'
                //Doesn't Print
                sh 'echo ${TEST_VAR}'
                //prints
                sh "echo ${TEST_VAR}"
                //prints
                sh "echo ${env.TEST_VAR}"
            }
        }
        stage('Container env') {
            steps {
                container('maven') {
                    echo 'Environment variables in container:'
                    sh 'env'
                    //PRINTS - works without double quote
                    sh 'echo ${TEST_VAR}'
                }
            }
        }
    }
  }