Symfony 4: Contributing Recipes

Fabien Potencier
4 min readApr 18, 2017


Symfony Flex is not Open-Sourced yet, but I can already feel the excitement in the community. I have also received some feedback via Twitter, Slack, and email during the last few days. That makes me really happy!

Everybody knows that I like to tease. Trying to build the momentum on something you have been working on for months feels great. But the reality is a bit more complex: I am still working on the first MVP of the infrastructure needed to support Symfony Flex. To be honest, I’m probably working on something that is a bit more than just an MVP.

The good news is that I’m almost there. The bad news is that some feedback made me realize that some features I had on my todo list for later need to be part of the first version. You know, that “one more feature” that will make Symfony Flex the next killer application for the Symfony community.

People are worried about the opinionated recipe repository. Keep in mind that one of the main goals of Symfony Flex is to automate your day-to-day workflow for the happy path.

First, I want to reiterate that a package does not need to have a recipe to be installed. The good old way of registering bundles manually and copy/pasting some default configuration will still work fine… which is what everybody has been doing for years. In other words, everything will be at least as easy to install as it is now.

Then, for several reasons I explained in my previous post, I won’t change my mind about the official repository being opinionated. I talk to a lot of developers and companies using Symfony, and many want “us” to make choices for them. They don’t want to test dozens of bundles to make an informed choice.

Finally, I need to reveal one more recipe configuration option that I did not mention yet: aliases. Instead of using the regular Composer package name, a recipe can list alternative shorter names. For instance, use composer req cli instead of composer req symfony/console. You can imagine packages willing to reserve the admin, api, or orm aliases. And of course, each alias can only be linked to one Composer package.

Choices are good.

But what about having another recipe repository along side the main one? Well, that feature was on my todo list for a future version. But I have decided to include it now. For the first version. And I like it a lot.

Let’s dive into the Symfony Flex recipe repositories. Instead of having just one repository, Symfony Flex supports two.

Here is how it works:

  • The “main” official repository, hosted at will be opinionated. Submissions will be reviewed carefully. They will need approval from the Symfony core team (like pull requests on the main symfony/symfony repository). We want the utmost quality and the best developer experience.
  • The “contrib” repository, hosted at will not be opinionated. Curated by the community at large, most submissions will be accepted.

Other than the rules to accept submissions, the “main” and the “contrib” repositories work in the exact same way, except for the following differences:

  • Only the “main” repository can define aliases (that makes sense I suppose);
  • By default, Symfony Flex only searches recipes in the “main” repository. Using the “contrib” repository is opt-in. Enable it by executing composer config extra.symfony.allow-contrib true.

And packages can be promoted from the “contrib” repository to the “main” one as well.

To maintain a high level of quality, I have also developed a set of validation rules for recipes. When you submit a pull request on both repositories, the Symfony Flex server runs a series of checks to ensure that your changes are valid. Basic checks like validating the existence of the package on Packagist. And more interesting ones like checking that two packages do not define the same alias.

But more interesting, a dedicated staging Flex Server is built for every pull request. That allows anyone to test the changes before they are merged into the master/production branch of a repository.

For instance, if you submit a pull request (number 42) on the “contrib” repository that adds a recipe for package “foo/bar”, install your new package by defining the SYMFONY_ENDPOINT environment variable:

SYMFONY_ENDPOINT= composer req foo/bar

If changes are submitted for “core” packages (like in symfony/framework-bundle), using the environment variable even works with composer create-project:

SYMFONY_ENDPOINT= composer create-project symfony/skeleton demo

Originally published at



Fabien Potencier

founder and CEO @SensioLabs and @blackfireio, founder and project lead @Symfony