pipeline {
  agent any

  stages {
    stage('Checkout') {
      steps {
        checkout scm
      }
    }

    stage('Build Image') {
      steps {
        echo 'Building image...'
        // --pull ensures base layer is fresh; tag includes BUILD_NUMBER to avoid cache clashes
        sh 'docker build --pull -t my-python-app:${BUILD_NUMBER} .'
      }
    }

    stage('Run Container') {
      steps {
        echo 'Running container...'
        // --rm cleans up; this will print "Hello, World!" to the console
        sh 'docker run --rm --name my-python-app-${BUILD_NUMBER} my-python-app:${BUILD_NUMBER}'
      }
    }

    stage('(Optional) Verify Output') {
      steps {
        script {
          // Re-run capturing output to assert expected behavior (example)
          def out = sh(
            script: 'docker run --rm my-python-app:${BUILD_NUMBER}',
            returnStdout: true
          ).trim()
          if (out != 'Hello, World!') {
            error "Unexpected output: '${out}'"
          }
        }
      }
    }
  }

  post {
    always {
      // Best-effort cleanup of any leftover container/image for this build tag
      sh '''
        docker rm -f my-python-app-${BUILD_NUMBER} 2>/dev/null || true
        docker image rm my-python-app:${BUILD_NUMBER} 2>/dev/null || true
      '''
    }
  }
}
``