Symfony Components in a Legacy application - http://tech.yappa.be/symfony-components-in-a-legacy-php-application

bin_console.php

#!/usr/bin/env php
<?php

include_once 'app/global_vars.php';

require ROOT_DIR . 'vendor/autoload.php';


use Application\Command\InsertFixturesCommand;
use Symfony\Component\Console\Application;

$application = new Application();
$application->add(new InsertFixturesCommand);
$application->run();

bootstrap.php

<?php

include_once 'app/global_vars.php';

require ROOT_DIR . 'vendor/autoload.php';


$container = new ContainerBuilder();
$loader = new YamlFileLoader($container, new FileLocator(ROOT_DIR . 'app/config/'));
$loader->load('services.yml');
$loader->load('parameters.yml');
$container->setParameter('root_dir', ROOT_DIR);
$container->setParameter('env', ENVIRONMENT);
$container->compile();

// boot legacy application logic
$legacyFrontController = new \Application\Controller\LegacyFrontController($container);
echo $legacyFrontController->start();

composer.json

{
    "require": {
        "php": "^5.6",
        "doctrine/annotations": "^1.2",
        "doctrine/cache": "^1.6",
        "doctrine/common": "^2.5",
        "doctrine/dbal": "^2.5",
        "doctrine/orm": "^2.5",
        "symfony/config": "^3.1",
        "symfony/console": "^3.1",
        "symfony/dependency-injection": "^3.1",
        "symfony/expression-language": "^3.1",
        "symfony/finder": "^3.1",
        "symfony/form": "^3.1",
        "symfony/http-foundation": "^3.1",
        "symfony/http-kernel": "^3.1",
        "symfony/routing": "^3.1",
        "symfony/security-csrf": "^3.1",
        "symfony/twig-bridge": "^3.1",
        "symfony/validator": "^3.1",
        "symfony/var-dumper": "^3.1",
        "symfony/yaml": "^3.1",
        "twig/twig": "~2.0@dev"
    }
}

controller_resolving.php

<?php


use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpKernel\Controller\ControllerResolver;
use Symfony\Component\Routing\Matcher\UrlMatcher;

/** @var Request $request */
$request = Request::createFromGlobals();
/** @var UrlMatcher $urlMatcher */
$urlMatcher = $this->container->get('route.url_matcher');
/** @var ControllerResolver $controllerResolver */
$controllerResolver = $this->container->get('route.controller_resolver');
    
$request->attributes->add($urlMatcher->match($request->getPathInfo()));
$controller = $controllerResolver->getController($request);

form.php

<?php
use Symfony\Component\Form\Form;

/** @var Form $form */
$form = $this->container->get('form.factory')->getFormFactory()->create(CustomType::class, $modelClass);

routing.yml

index:
    path:     /
    defaults: { _controller: 'Application\Controller\HomeController::indexAction'}

profile_index:
    path:     /profile
    defaults: { _controller: 'Application\Controller\ProfileController::indexAction' }

services.yml

services:
    request:
        class: Symfony\Component\HttpFoundation\Request
        factory: [Symfony\Component\HttpFoundation\Request, createFromGlobals]

    request.context:
        class: Symfony\Component\Routing\RequestContext
        calls:
            - ["fromRequest", ["@request"]]

    route.file_locator:
        class: Symfony\Component\Config\FileLocator
        arguments:
            - ["%root_dir%/app/config"]

    route.yaml_file_loader:
        class: Symfony\Component\Routing\Loader\YamlFileLoader
        arguments:
            - "@route.file_locator"

    router:
        class: Symfony\Component\Routing\Router
        arguments:
            - "@route.yaml_file_loader"
            - "routing.yml"
            - []
            - null
            - null

    route.url_matcher:
        class: Symfony\Component\Routing\Matcher\UrlMatcher
        arguments:
            - "@=service('router').getRouteCollection()"
            - "@request.context"

    route.controller_resolver:
        class:  Symfony\Component\HttpKernel\Controller\ControllerResolver

    twig.loader:
        class: Twig_Loader_Filesystem
        calls:
            - ["addPath", ["%root_dir%/src/Resources/views/"]]
            - ["addPath", ["%root_dir%/vendor/symfony/twig-bridge/Resources/views/"]]

    twig:
        class: Twig_Environment
        arguments:
            - "@twig.loader"
            -
                cache: "%cache_dir%/Twig"
                debug: true
        calls:
            - ["addExtension", ["@twig.translation_extension"]]
            - ["addExtension", ["@twig.route_extension"]]
            - ["addExtension", ["@twig.form_extension"]]

    twig.translation_extension:
        class: Symfony\Bridge\Twig\Extension\TranslationExtension
        arguments:
            - "@translator"

    twig.form_engine:
        class: Symfony\Bridge\Twig\Form\TwigRendererEngine
        arguments: [["Form/form_div_layout.html.twig"]]
        calls:
            - ["setEnvironment", ["@twig"]]

    twig.form_renderer:
        class: Symfony\Bridge\Twig\Form\TwigRenderer
        arguments: ["@twig.form_engine"]

    twig.route_extension:
        class: Symfony\Bridge\Twig\Extension\RoutingExtension
        arguments:
            - "@router"

    twig.form_extension:
        class: Symfony\Bridge\Twig\Extension\FormExtension
        arguments: ["@twig.form_renderer"]

    csrf.token_generator:
        class: Symfony\Component\Security\Csrf\TokenGenerator\UriSafeTokenGenerator

    csrf.token_storage:
        class: Symfony\Component\Security\Csrf\TokenStorage\NativeSessionTokenStorage

    csrf.manager:
        class: Symfony\Component\Security\Csrf\CsrfTokenManager
        arguments:
            - "@csrf.token_generator"
            - "@csrf.token_storage"

    form.csrf_extension:
        class: Symfony\Component\Form\Extension\Csrf\CsrfExtension
        arguments:
            - "@csrf.manager"
            - "@translator"

    translator.xliff_file_loader:
        class: Symfony\Component\Translation\Loader\XliffFileLoader

    translator:
        class: Symfony\Component\Translation\Translator
        arguments:
            - "nl_NL"
        calls:
            - ["addLoader", ["xlf", "@translator.xliff_file_loader"]]
            - ["addResources", ["xlf", "%root_dir%/vendor/symfony/validator/Symfony/Component/Validator/Resources/translations/validators.nl.xlf", "nl_NL", "messages"]]
            - ["setFallbackLocales", ["nl"]]

    validator:
        class: Symfony\Component\Validator\ValidatorBuilder
        factory: [Symfony\Component\Validator\Validation, createValidatorBuilder]
        calls:
            - ["enableAnnotationMapping"]

    form.http_extension:
        class: Symfony\Component\Form\Extension\HttpFoundation\HttpFoundationExtension

    form.validator_extension:
        class: Symfony\Component\Form\Extension\Validator\ValidatorExtension
        arguments:
            - "@=service('validator').getValidator()"

    form.factory:
        class: Symfony\Component\Form\FormFactoryBuilder
        factory: [Symfony\Component\Form\Forms, createFormFactoryBuilder]
        calls:
            - ["addExtension", ["@form.http_extension"]]
            - ["addExtension", ["@form.csrf_extension"]]
            - ["addExtension", ["@form.validator_extension"]]

var_dumper.php

<?php

...
dump($variable);
...

Don't do that:

        arguments:
            - "@=service('router').getRouteCollection()"
            - "@request.context"

It will make Symfony initialization time very long.