Learning Jenkins Pipeline via trial and error. This is what I've come up with so far. The "tools" are PHP testing and metrics installed via composer stored in their own build/tools/composer.json. AWS ECR is used to store my docker images, you can use php/xxx from Docker HUB.

build-tools-composer.json

{
  "require": {
    "phing/phing": "^2.16",
    "phploc/phploc": "^4.0",
    "pdepend/pdepend": "~2.5.0",
    "sebastian/phpcpd": "^3.0",
    "phpmd/phpmd": "2.6",
    "squizlabs/php_codesniffer": "*",
    "pear/http_request2": "^2.3",
    "phpunit/phpunit": "6.1",
    "phpunit/dbunit": "^3.0",
    "theseer/phpdox": "^0.10.1",
    "jakub-onderka/php-parallel-lint": "^0.9.2"
  }
}

Jenkinsfile

#!groovy
pipeline {
    agent any

//    triggers {
//      cron('H 4/* 0 0 1-5')
//    }

//    tools {
//      nodejs 'Node 6.x'
//    }

    parameters {
      string(name: 'GIT_URL', defaultValue: 'https://github.com/xxx.git', description: 'URL to your repository')
      string(name: 'GIT_CREDENTIALS', defaultValue: '', description: 'Credential ID for your repository')
      string(name: 'GIT_BRANCH', defaultValue: 'master', description: 'Branch of your repository')
      string(name: 'AWS_URL', defaultValue: 'https://xxx', description: 'URL of your AWS ECR repository, example: "https://__ACCOUNTID__.dkr.ecr.__REGION__.amazonaws.com"')
      string(name: 'AWS_CREDENTIALS', defaultValue: 'ecr:xxx', description: 'Credential ID for your AWS repository, example: "ecr:REGION:CREDENTIALID""')
      string(name: 'AWS_PHP_TAG', defaultValue: 'xxx', description: 'ECR repository tag for PHP cli')
      string(name: 'TOOLS_BIN_PATH', defaultValue: 'build/tools/vendor/bin', description: 'Tools are stored in build/tools, this is the relative path to your app')
      string(name: 'TOOLS_APP_PATH', defaultValue: './app', description: 'Tools are stored in build/tools, this is the relative path to your app')
    }

    environment {
       ENVIRONMENT = "production"
       NODE_ENV = "production"
       COMPOSER_HOME = "${env.HUDSON_HOME}"
    }

    stages {
      stage ('Checkout') {
        steps {
          git branch: "${params.GIT_BRANCH}", credentialsId: "${params.GIT_CREDENTIALS}", url: "${params.GIT_URL}"
        }
      }

      stage('Build') {
        steps {
          /* Do your building stuff here, npm, gulp, composer, etc */
          script {
            docker.image('composer:latest').inside{
              sh 'composer install -a --no-dev --ignore-platform-reqs --no-scripts --no-interaction --no-ansi --no-progress'
            }
          }

        }
      }

      stage('Test'){
        steps {
          // clean up directories
          sh 'rm -rf build/api build/coverage build/logs build/pdepend build/phpdox'
          sh 'mkdir build/api build/coverage build/logs build/pdepend build/phpdox'

          script {
            docker.withRegistry("${params.AWS_URL}", "${params.AWS_CREDENTIALS}") {
              // Get build tools via composer
              docker.image('composer:latest').inside{
                sh 'cd build/tools && composer install -a --ignore-platform-reqs --no-scripts --no-interaction --no-ansi --no-progress'
              }
              docker.image("${params.AWS_PHP_TAG}").inside{
                // PHP Lint
                sh "${params.TOOLS_BIN_PATH}/parallel-lint --exclude vendor/ ${params.TOOLS_APP_PATH}"
                // PHPUnit
                sh "${params.TOOLS_BIN_PATH}/phpunit -c build/phpunit.xml || exit 0"
                // PHP Codestyle
                sh "${params.TOOLS_BIN_PATH}/phpcs --report=checkstyle --report-file=`pwd`/build/logs/checkstyle.xml --standard=Zend --extensions=php --ignore=autoload.php --ignore=vendor/ ./app || exit 0"
                // Copy & Paste detection
                sh "${params.TOOLS_BIN_PATH}/phpcpd --log-pmd build/logs/pmd-cpd.xml --exclude vendor ${params.TOOLS_APP_PATH} || exit 0"
                // Mess detection
                sh "${params.TOOLS_BIN_PATH}/phpmd . xml build/phpmd.xml --reportfile build/logs/pmd.xml --exclude vendor/ || exit 0"
              }
            }
          }

          // phpunit reporting
          step([
              $class: 'XUnitBuilder',
              thresholds: [[$class: 'FailedThreshold', unstableThreshold: '1']],
              tools: [[$class: 'JUnitType', pattern: 'build/logs/junit.xml']]
          ])
          publishHTML([allowMissing: false, alwaysLinkToLastBuild: false, keepAll: false, reportDir: 'build/coverage', reportFiles: 'index.html', reportName: 'Coverage Report', reportTitles: ''])

          // jenkins plugin not working with pipeline yet @see https://github.com/jenkinsci/cloverphp-plugin/pull/6
          //step([$class: 'CloverPHPPublisher',cloverXml: 'build/logs/clover.xml'])
          // jenkins plugin not working with pipeline yet
          //step([$class: 'Crap4JPublisher', reportPattern: 'build/logs/crap4j.xml', healthThreshold: '10'])

          // checkstyle reporting
          checkstyle pattern: 'build/logs/checkstyle.xml'

          // Copy & Paste detection reporting
          dry canRunOnFailed: true, pattern: 'build/logs/pmd-cpd.xml'

          // Mess detection reporting
          pmd canRunOnFailed: true, pattern: 'build/logs/pmd.xml'
          }
        }

        stage('Documentation') {
          steps {
            script {
              docker.withRegistry("${params.AWS_URL}", "${params.AWS_CREDENTIALS}") {
                docker.image("${params.AWS_PHP_TAG}").inside{
                  // LOC
                  sh "${params.TOOLS_BIN_PATH}/phploc --count-tests --exclude vendor/ --log-csv build/logs/phploc.csv --log-xml build/logs/phploc.xml ${params.TOOLS_APP_PATH}"
                  // PDepend
                  sh "${params.TOOLS_BIN_PATH}/pdepend --jdepend-xml=build/logs/jdepend.xml --jdepend-chart=build/pdepend/dependencies.svg --overview-pyramid=build/pdepend/overview-pyramid.svg --ignore=vendor --ignore=build ${params.TOOLS_APP_PATH}"
                  // PHPDox
                  sh "${params.TOOLS_BIN_PATH}/phpdox -f build/phpdox.xml"
                }
              }
            }
          }
        }

        stage('Deploy') {
            steps {
                echo 'Deploying'
            }
        }
    }
}