How to Manage Configuration in Symfony without Bundle, Extension, and Configuration?

2018-11-29

Symfony Flex is moving towards of bundle-less applications. That doesn't mean you should create a monolith code in /src as fast as possible, but rather control everything via .yaml and .env files. It's takes few steps to remove extension and move to import of services.yaml.

But how would you approach a simple task as setup an account number parameter?

If you hear about the trend of "no-bundle" application for the first time, is very nicely summarized in 10 points in SymfonyCasts. Go check it, I'll wait here.

1. How this Affected Service Registration?

Before you need 3 classes to get services to the application:

/app
    AppKernel.php
/packages
    /accountant
        /src
            /DependencyInjection
                AccountantExtension.php
            AccountantBundle.php
        /config
            services.yaml

<?php declare(strict_types=1);

namespace App;

use Project\Accountant\AccountantBundle;
use Symfony\Component\HttpKernel\Kernel;
use Symfony\Component\HttpKernel\Bundle\BundleInterface;

final class AppKernel extends Kernel
{
    /**
     * @return BundleInterface[]
     */
    public function registerBundles(): array
    {
        return [new AccountantBundle];
    }

    // ...
}

<?php declare(strict_types=1);

namespace Project\Accountant;

use Project\Accountant\DependencyInjection\AccountantExtension;
use Symfony\Component\HttpKernel\Bundle\Bundle;

final class AccountantBundle extends Bundle
{
 public function getContainerExtension()
    {
        return new AccountantExtension();
    }
}

<?php declare(strict_types=1);

namespace Project\Accountant\DependencyInjection;

use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Extension\Extension;
use Symfony\Component\DependencyInjection\Loader\YamlFileLoader;
use Symfony\Component\Config\FileLocator;

final class AccountantExtension extends Extension
{
    public function load(array $configs, ContainerBuilder $container)
    {
        $loader = new YamlFileLoader($container, new FileLocator(__DIR__.'/../../config'));
        $loader->load('services.yaml');
    }
}

# packages/accountant/config/services.yaml
services:
    Project\Accountant\:
        resource: "../src"

Now we can drop all of the PHP magic code down:

 /app
     AppKernel.php
 /packages
     /accountant
         /src
-            /DependencyInjection
-                AccountantExtension.php
-            AccountantBundle.php
         /config
             services.yaml

...and load services in local config:

# app/config.yaml
imports:
   - { resource: "packages/accountant/config/services.yaml" }

Or we can set this up just once for all local packages with glob:

# app/config.yaml
imports:
   - { resource: "packages/*/config/services.yaml" }

We deleted all PHP files and add 2 lines to config - that's what a good trade, right? Much less code can go wrong and the result is easy to read even for a programmer who was just hired today.

I think most of you already know this configuration shift and use it for months, right? Now the harder part, that many people still struggle with.

2. How this Affected Configuration?

In the "accountant" package we have a service that sends money... no ordinary money, Bitcoins! And we need to set an account number parameter to it:

<?php declare(strict_types=1);

namespace Project\Accountant;

final class BitcoinSender
{
    /**
     * @param string
     */
    private $accountNumber;

    public function __construct(string $accountNumber)
    {
        $this->accountNumber = $accountNumber;
    }

    public function donateTo(float $amount, string $targetAccountNumber)
    {
        // move $amount
        // from $this->accountNumber
        // to $targetAccountNumber
    }
}

The configuration of $accountNumber value in bundle-school paradigm looks like this:

 # packages/accountant/config/services.yaml
+accountant:
+     account_number: "123_secret_hash"
+
 services:
     Project\Accountant\:
         resource: "../src"

<?php declare(strict_types=1);

namespace Project\Accountant;

use Project\Accountant\DependencyInjection\AccountantExtension;
use Symfony\Component\HttpKernel\Bundle\Bundle;

final class AccountantBundle extends Bundle
{
    public function getContainerExtension()
    {
        return new AccountantExtension();
    }
}

<?php declare(strict_types=1);

namespace Project\Accountant\DependencyInjection;

use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Extension\Extension;

final class AccountantExtension extends Extension
{
    public function load(array $configs, ContainerBuilder $container)
    {
        $configuration = new AccountantConfiguration();
        $config = $this->processConfiguration($configuration, $configs);

        // for bitcoin sender
        $container->getDefinition('Project\Accountant\BitcoinSender')
            ->setArgument('accountNumber', $config['account_number']);

        // for further use (optional)
        // $container->setParameter('account_number', $config['account_number']);
    }
}

<?php declare(strict_types=1);

namespace Project\Accountant\DependencyInjection;

use Symfony\Component\Config\Definition\Builder\TreeBuilder;
use Symfony\Component\Config\Definition\ConfigurationInterface;

final class AccountantConfiguration implements ConfigurationInterface
{
    public function getConfigTreeBuilder(): TreeBuilder
    {
        $treeBuilder = new TreeBuilder();
        $rootNode = $treeBuilder->root('accountant');
        $rootNode
            ->children()
                ->scalarNode('account_number')
                ->end()
            ->end();

        return $treeBuilder;
    }
}

All this fuss just to load single parameter? Not anymore:

 /app
     AppKernel.php
 /packages
     /accountant
         /src
-            /DependencyInjection
-                AccountantExtension.php
-                AccountantConfiguration.php
-            AccountantBundle.php
         /config
             services.yaml

All cleaned up. We run the app and...

ERROR: "$accountNumber" argument was not set

Damn! What now?

What Options do We Have?

1. Keep the Extension

<?php

$container->getDefinition('Project\Accountant\BitcoinSender')
    ->setArgument('accountNumber', $config['account_number']);

❌

We want to get rid of this code, not to maintain it.

2. Set Parameter Manually in the Config

 # packages/accountant/config/services.yaml
-accountant:
+parameters:
     account_number: "123_secret_hash"

 services:
     Project\Accountant\:
         resource: "../src"

+    Project\Accountant\BitcoinSender:
+        arguments:
+            $accountNumber: "%account_number%"

We want config to use PSR-4 autodiscovery to it's fullest potential, not go back to manual service definitions.

3. Bind the parameter

Good idea! Since Symfony 3.4 we can do this:

 # packages/accountant/config/services.yaml
-accountant:
+parameters:
     account_number: "123_secret_hash"

 services:
+    _defaults:
+        bind:
+            $accountNumber: "%account_number%"
+
     Project\Accountant\:
         resource: "../src"

✅

4. Autowire the Parameter

<?php declare(strict_types=1);

namespace App;

use Symplify\PackageBuilder\DependencyInjection\CompilerPass\AutowireArrayParameterCompilerPass;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\HttpKernel\Kernel;

final class AppKernel extends Kernel
{
    protected function build(ContainerBuilder $container): void
    {
        $container->addCompilerPass(new AutowireArrayParameterCompilerPass());
    }
}

You set up this only once, but then you can enjoy short and clear configs:

 # packages/accountant/config/services.yaml
-accountant:
+parameters:
     account_number: "123_secret_hash"

 services:
     Project\Accountant\:
         resource: "../src"

✅

This compiler autowires parameters by convention:

%parameter_name% => $parameterName

You can read more about it here.

Final Results

So how does our bundle-less application looks like in the end?

we got rid of the Configuration class - no more tree fluent builds for a bunch of parameters
we got rid of the Extension class - no more relative paths
we got rid of the Bundle class - no more createExtension(), getExtension() typos
we gain parameter binding/autowiring

We work with configs that clearly state all we parameters and services we use. Explicit, clear, in one place.

How do you approach parameter for your packages (previously bundles) in Symfony 4 applications?

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