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Symfony Flex & Aliases

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It's time to demystify something incredible: tractor beams. Well actually, we haven't figured those out yet... so let's demystify something else, something that's already been happening behind the scenes. First commit everything, with a nice message:


Wait! Run git init first before git add .: Symfony no longer creates a Git repo automatically for you :)

git init
git add .
git commit -m "making so much good progress"

Installing the Security Checker

Let's install a new feature called the Symfony Security Checker. This is a great tool.... but... full disclosure: we're mostly installing it to show off the recipe system. Ooooo. Run:

git status

Ok, there are no changes. Now run:

composer require sec-checker


This package will only be used while developing. So, it would be even better to run composer require sec-checker --dev.

Hello Symfony Flex

Once again, sec-checker should not be a valid package name! So what's going on? Move over and open composer.json:

64 lines | composer.json
// ... lines 2 - 3
"require": {
// ... lines 5 - 8
"symfony/flex": "^1.0",
// ... lines 10 - 13
// ... lines 15 - 62

Our project began with just a few dependencies. One of them was symfony/flex: this is super important. Flex is a Composer plugin with two superpowers.

Flex Aliases

The first superpower is the alias system. Find your browser and go to symfony.sh.

This is the Symfony "recipe" server: we'll talk about what that means next. Search for "security". Ah, here's a package called sensiolabs/security-checker. And below, it has aliases: sec-check, sec-checker, security-check and more.

Thanks to Flex, we can say composer require sec-checker, or any of these aliases, and it will translate that into the real package name. Yep, it's just a shortcut system. But the result is really cool. Need a logger? composer require logger. Need to send emails? composer require mailer. Need a tractor beam? composer require, wait, no, we can't help with that one.

Back in composer.json, yep! Composer actually added sensiolabs/security-checker:

64 lines | composer.json
// ... lines 2 - 14
"require-dev": {
"sensiolabs/security-checker": "^4.1",
// ... line 17
// ... lines 19 - 62

That's the first superpower of Flex.

Flex Recipes

The second superpower is even better: recipes. Mmmm. Go back to your terminal and... yes! It did install and, check this out: "Symfony operations: 1 recipe". Then, "Configuring sensiolabs/security-checker".

What does that mean? Run:

git status

Woh! We expected composer.json and composer.lock to be updated. But there are also changes to a symfony.lock file and we suddenly have a brand new config file!

First, symfony.lock: this file is managed by Flex. It keeps track of which recipes have been installed. Basically... commit it to git, but don't worry about it.

The second file is config/packages/dev/security_checker.yaml:

public: false
arguments: ['@SensioLabs\Security\SecurityChecker']
- { name: console.command }

This was added by the recipe and, cool! It adds a new bin/console command to our app! Don't worry about the code itself: you'll understand and be writing code like this soon enough!

The point is this: thanks to this file, we can now run:

php bin/console security:check

Cool! This is the recipe system in action! Whenever you install a package, Flex will execute the recipe for that package, if there is one. Recipes can add configuration files, create directories, or even modify files like .gitignore so that the library instantly works without any extra setup. I love Flex.

By the way, the purpose of the security checker is that it checks to see if there are any known vulnerabilities for packages used in our project. Right now, we're good!

But the recipe made one other change. Run:

git diff composer.json

Of course, composer require added the package. But the recipe added a new script!

64 lines | composer.json
// ... lines 2 - 40
"scripts": {
"auto-scripts": {
// ... lines 43 - 44
"security-checker security:check": "script"
// ... lines 47 - 52
// ... lines 54 - 62

Thanks to that, whenever we run:

composer install

when it finishes, it runs the security checker automatically. So cool!

Oh, and I won't show it right now, but Flex is even smart enough to uninstall the recipes when you remove a package. That makes testing out new packages fast and easy.

The Recipes Repository

So you might be wondering... where do these recipes live? Great question! They live... in the cloud. I mean, they live on GitHub. On symfony.sh, click "Recipe" next to the Security checker. Ah, it takes us to the symfony/recipes repository. Here, you can see what files will be added and a few other changes described in manifest.json.

All recipes either live in this repository, or another one called symfony/recipes-contrib. There's no important difference between the two repositories: but the official recipes are watched more closely for quality.

Next! Let's put the recipe system to work by installing Twig so we can create proper templates.