Eating spaghetti with Symfony

Big-bang migrations hardly ever work and usually take significantly more effort than expected. It's also hard to convince the stakeholders there's any value in the whole operation. It's much more effective to make gradual improvements. It's also more rewarding to celebrate success after every sprint. Learn how to leverage Symfony to move away from an Old School PHP Spaghetti Project™ to a modern Symfony based application. Release after the first iteration and keep improving the code base, delivering value in the same time.

Transcript

1. @jakub_zalas
   @jakzal
   Jakub Zalas
   EATING SPAGHETTI WITH
   SYMFONY
   PHP UK 2016
   https://www.flickr.com/photos/stijnnieuwendijk/8839597194/in/photostream/
   

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2. https://www.flickr.com/photos/ocarchives/3952964087/
   THE PLAN
   ➤ Spaghetti/legacy/mud
   ➤ Migration strategies
   ➤ Migration cookbook
   https://flic.kr/p/72iYve
   

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3. SPAGHETTI, LEGACY, BIG BALL OF MUD
   Twisted and tangled as a bowl of spaghetti.
   Legacy code relates to a no-longer supported technology.
   Legacy code is code with no tests.
   Legacy code is source code inherited from someone else.
   A big ball of mud is haphazardly
   structured, sprawling, sloppy, duct-tape
   and bailing wire, spaghetti code jungle.
   

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4. THERE’S A BRIGHT SIDE
   ➤ it works
   ➤ it brings (or saves) money
   ➤ it’s a source of domain knowledge
   and… always look on the bright side of life
   

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5. WHY MIGRATE?
   ➤ adding features takes ages
   ➤ obsolete technology
   ➤ scaling
   https://www.flickr.com/photos/sdobie/8226246821/
   

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6. MIGRATION STRATEGIES
   Migrating Legacy Systems: Gateways, Interfaces & the Incremental Approach by Michael Stonebraker and Michael L. Brodie
   Cold Turkey Chicken Little
   vs
   

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7. COOKBOOK
   ideas to build on
   https://flic.kr/p/7EbFkK
   

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8. Write tests for any new feature, bug, or any piece of code you’re changing.
   Writing tests-first is the best way to enforce a better design,
   and eventually crawl out of legacy.
   https://flic.kr/p/DmE99L
   

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9. COMPONENTS
   taking small steps
   https://flic.kr/p/7PQ15Q
   

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10. PUTTING TWIG TO WORK
    $loader = new Twig_Loader_Filesystem(__DIR__.'/templates');

    

    $twig = new Twig_Environment($loader, [

    'cache' => __DIR__.'/../var/cache/legacy/twig',

    'debug' => true,

    ]);
    

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11. PUTTING TWIG TO WORK
    echo $twig->render('home.html.twig', ['foo' => 'bar']);
    

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12. LEVERAGING THE SERVICE CONTAINER - CREATING SERVICE DEFINITIONS
    $container = new ContainerBuilder();

    $container->setParameter('database_path', __DIR__.'/../db');

    $container

    ->register('db', 'PDO')

    ->addArgument('sqlite:%database_path%');

    

    $container

    ->register('foo_repository', 'FooRepository')

    ->addArgument(new Reference('db'));
    

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13. LEVERAGING THE SERVICE CONTAINER - CREATING SERVICE DEFINITIONS
    use Symfony\Component\DependencyInjection\ContainerBuilder;

    use Symfony\Component\Config\FileLocator;

    use Symfony\Component\DependencyInjection\Loader\YamlFileLoader;

    

    $container = new ContainerBuilder();

    $loader = new YamlFileLoader($container, new FileLocator(__DIR__));

    $loader->load('services.yml');
    

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14. LEVERAGING THE SERVICE CONTAINER - CREATING SERVICE DEFINITIONS
    # services.yml
    parameters:

    database_path: '%kernel.root_dir%/db'

    

    services:

    pdo:

    class: PDO

    arguments: [sqlite:%database_path%]

    foo_repository:

    class: FooRepository

    arguments: [@pdo]
    

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15. LEVERAGING THE SERVICE CONTAINER - CACHING
    $file = __DIR__.'/../cache/container.php';

    

    if (file_exists($file)) {

    require_once $file;

    $container = new ProjectServiceContainer();

    } else {

    $container = new ContainerBuilder();

    // ...

    $container->compile();

    

    $dumper = new PhpDumper($container);

    file_put_contents($file, $dumper->dump());

    }
    

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16. LEVERAGING THE SERVICE CONTAINER - USAGE
    $foo = $container->get('foo_repository')->findFoo(42);
    

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17. LEVERAGING THE EVENT DISPATCHER
    Subjects Listeners
    Event Dispatcher
    Mailer Listener
    Registration Dispatcher
    call
    notify
    registration.success
    add listener
    registration.success
    register
    

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18. LEVERAGING THE EVENT DISPATCHER
    Subjects Listeners
    Event Dispatcher
    Mailer
    Listener
    Registration Dispatcher
    call
    notify
    registration.success
    add listener
    registration.success
    SMS
    Listener
    add listener
    registration.success
    call
    register
    

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19. LEVERAGING THE EVENT DISPATCHER
    use Symfony\Component\EventDispatcher\EventDispatcher;

    

    $dispatcher = new EventDispatcher();

    $dispatcher->addListener(

    'registration.success',

    function (Event $event) {}

    );

    $dispatcher->addListener(

    'registration.success',

    [$listener, 'onRegistrationSuccess']

    );
    

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20. LEVERAGING THE EVENT DISPATCHER
    $event = new UserRegisteredEvent($user);

    $dispatcher->dispatch('registration.success', $event);
    

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21. LEVERAGING MESSAGE QUEUES
    Consumer
    Legacy
    Message
    broker
    produce consume
    Consumer
    Consumer
    

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22. LEVERAGING MESSAGE QUEUES
    curl -i -u user:pass \
    -H "content-type:application/json" \
    -XPOST http://rabbtmiq:15672/api/exchanges/%2f/image-resize/publish \
    -d '{
    “properties":{},
    “payload":"cat.png",
    "payload_encoding":"string",
    “routing_key”:""
    }'
    https://github.com/php-amqplib/php-amqplib
    https://github.com/php-amqplib/RabbitMqBundle
    

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23. CUT, SLICE, EXTRACT
    Clear separation
    https://flic.kr/p/4vRMY3
    

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24. WRAPPING THE LEGACY APP
    Symfony
    FooController
    BarController
    Router
    LegacyController Legacy
    GET /products
    

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25. WRAPPING THE LEGACY APP
    # app/config/routing.yml

    

    app:

    resource: "@AppBundle/Controller/"

    type: annotation

    

    legacy:

    path: /{path}

    defaults: { _controller: AppBundle:Legacy:forward }

    requirements:

    path: .*
    

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26. WRAPPING THE LEGACY APP
    // src/AppBundle/Controller/BlogController.php

    

    namespace AppBundle\Controller;

    

    use Symfony\Component\HttpFoundation\Response;

    

    final class LegacyController

    {

    public function forwardAction($path)

    {

    ob_start();
    

    require __DIR__.’/../../../legacy/index.php';
    

    $content = ob_get_clean();

    

    return new Response($content);

    }

    }
    

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27. SHARING THE SESSION
    framework:

    session:

    storage_id: session.storage.php_bridge

    save_path: /tmp

    handler_id: session.handler.native_file
    Hint: to access the legacy session from Symfony:
    https://github.com/theodo/TheodoEvolutionSessionBundle
    

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28. PROXYING TO THE NEW APP
    Symfony
    Proxy
    Legacy
    GET /products
    

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29. PROXYING TO THE NEW APP
    # my-app.conf
    server {

    listen 80;

    server_name my-app.dev;

    root /my-app/legacy;

    

    location / {

    try_files $uri $uri/ /index.php$is_args$args;

    }

    

    location ~ ^/index\.php(/|$) {

    fastcgi_index index.php;

    fastcgi_pass my-app-php:9000;

    fastcgi_split_path_info ^(.+\.php)(/.*)$;

    include fastcgi_params;

    fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name;

    fastcgi_param DOCUMENT_ROOT $realpath_root;

    }

    }
    

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30. PROXYING TO THE NEW APP
    # my-app.conf
    server {

    listen 80;

    server_name my-app.dev;

    root /my-app/legacy;

    

    location ~ ^/products/.+ {

    proxy_pass http://v2.my-app.dev;

    }

    

    location / {

    try_files $uri $uri/ /index.php$is_args$args;

    }

    

    # ...

    }
    

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31. PROXYING TO THE NEW APP
    # v2.my-app.conf
    server {

    listen 80;

    server_name v2.my-app.dev;

    root /my-app/web;

    

    location / {

    try_files $uri $uri/ /app.php$is_args$args;

    }

    

    location ~ ^/app\.php(/|$) {

    fastcgi_index app.php;

    fastcgi_pass localhost:9000;

    fastcgi_split_path_info ^(.+\.php)(/.*)$;

    include fastcgi_params;

    fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name;

    fastcgi_param DOCUMENT_ROOT $realpath_root;

    fastcgi_param HTTP_HOST "my-app.dev";

    }

    

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32. GOING MICRO WITH THE MICRO KERNEL
    

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33. GOING MICRO WITH THE MICRO KERNEL
    final class AppKernel extends Kernel

    {

    use MicroKernelTrait;

    

    public function registerBundles()

    {

    return [

    new Symfony\Bundle\FrameworkBundle\FrameworkBundle(),

    new Symfony\Bundle\TwigBundle\TwigBundle(),

    ];

    }
    // ...

    }
    

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34. GOING MICRO WITH THE MICRO KERNEL
    final class AppKernel extends Kernel

    {

    // ...

    

    protected function configureContainer(
    ContainerBuilder $c, LoaderInterface $loader
    ) {

    $c->loadFromExtension('framework', [

    'secret' => '$ecret',

    'templating' => [

    'engines' => ['twig'],

    ],

    ]);

    }

    

    // ...

    }
    

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35. GOING MICRO WITH THE MICRO KERNEL
    final class AppKernel extends Kernel

    {

    // ...
    

    protected function configureRoutes(RouteCollectionBuilder $routes)

    {

    $routes->add('/products/{slug}', 'kernel:productAction');

    }

    

    public function productAction($slug)

    {

    $twig = $this->container->get('twig');

    $content = $twig->render(‘product.html.twig', ['slug' => $slug]);

    

    return new Response($content);

    }

    }
    

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36. GOING MICRO WITH THE MICRO KERNEL
    // web/app.php

    

    // use statements omitted

    

    require __DIR__.'/../vendor/autoload.php';

    

    final class AppKernel extends Kernel

    {

    // ...

    }
    

    $kernel = new AppKernel('dev', true);

    $request = Request::createFromGlobals();

    $response = $kernel->handle($request);

    $response->send();

    $kernel->terminate($request, $response);
    

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37. GOING FULL STACK
    final class AppKernel extends Kernel

    {

    // remove the trait

    // ...

    

    public function registerContainerConfiguration(LoaderInterface $loader)

    {

    return $loader->load(
    $this->getRootDir()
    .’/config/config_'.$this->getEnvironment().'.yml'
    );

    }

    }
    

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38. GOING FULL STACK
    # take parts relevant to you from symfony/symfony-standard configs

    imports:

    - { resource: parameters.yml }

    - { resource: security.yml }

    - { resource: services.yml }

    

    framework:

    secret: "%secret%"

    router:

    resource: "%kernel.root_dir%/config/routing.yml"

    strict_requirements: ~

    # ...

    

    twig:

    debug: "%kernel.debug%"

    strict_variables: "%kernel.debug%"
    

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39. DESIGNING SMALLER APPS
    Legacy
    Web
    Checkout
    Image
    Converter
    Web Product
    Catalog
    Inventory
    API
    

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40. HYBRID APPROACH
    a bit of both
    https://flic.kr/p/sqfbS
    

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41. ACCESSING THE SYMFONY KERNEL FROM A LEGACY APP
    Legacy
    GET /products
    Symfony
    

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42. ACCESSING THE SYMFONY KERNEL FROM A LEGACY APP
    use Symfony\Component\HttpFoundation\Request;
    $request = Request::createFromGlobals();

    $request->attributes->set('is_legacy', true);

    $request->server->set('SCRIPT_FILENAME', 'app.php');

    

    $kernel = new \AppKernel($environment, $debug);

    $kernel->boot();

    

    $container = $kernel->getContainer();

    $container->get('request_stack')->push($request);
    

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43. ACCESSING THE SYMFONY KERNEL FROM A LEGACY APP
    $container = $kernel->getContainer();

    

    

    $container->get('event_dispatcher')

    ->dispatch('registration.success', new Event());

    

    $container->get('twig')->render('template.html.twig');

    

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44. SHARING EVENTS - SYMFONY KERNEL EVENTS
    Request Response
    Controller Resolver
    Event Dispatcher
    kernel.request
    FragmentListener
    SessionListener
    LocaleListener
    RouterListener
    Firewall
    

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45. SHARING EVENTS - SYMFONY KERNEL EVENTS
    Request Response
    Controller Resolver
    Event Dispatcher
    ControllerListener
    kernel.controller
    RequestDataCollector
    Listener
    ParamConverter
    Listener
    TemplateListener
    

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46. SHARING EVENTS - SYMFONY KERNEL EVENTS
    Request Response
    Controller Resolver
    Event Dispatcher
    kernel.response
    CacheListener
    ResponseListener
    ProfilerListener
    WebDebugToolbarListener
    

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47. SHARING EVENTS - SYMFONY KERNEL EVENTS
    Request Response
    Controller Resolver
    Event Dispatcher
    kernel.finish_request
    LocaleListener RouterListener
    Firewall
    

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48. SHARING EVENTS - SYMFONY KERNEL EVENTS
    Request Response
    Controller Resolver
    Event Dispatcher
    TemplateListener
    kernel.view
    

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49. SHARING EVENTS - SYMFONY KERNEL EVENTS
    Request Response
    Controller Resolver
    Event Dispatcher
    kernel.terminate
    ProfilerListener
    EmailSenderListener
    

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50. SHARING EVENTS - SYMFONY KERNEL EVENTS
    $eventDispatcher = $container->get('event_dispatcher');

    

    $event = new GetResponseEvent(
    $kernel, $request, HttpKernelInterface::MASTER_REQUEST
    );

    $eventDispatcher->dispatch(KernelEvents::REQUEST, $event);
    

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51. EMBEDDING CONTROLLERS / ESI
    Legacy page
    
    

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52. EMBEDDING CONTROLLERS / ESI
    $inlineRenderer = $container->get('fragment.renderer.esi');

    

    echo $inlineRenderer->render('/foo', $request)->getContent();
    
    

    some foo content

    
    has surrogate capability no surrogate capability
    

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53. @jakub_zalas @jakzal
    Thank you.
    Rate my talk, please:
    https://joind.in/talk/85830
    

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