boekkooi / composer-monorepo-plugin

Integrates Composer into monolithic repositories with many packages.

Fiddler - The Composer Monorepo Plugin

Note: this project is still experimental. Please provide feedback!

Fiddler adds support for Monorepos when using Composer package manager. It introduces a maintainable approach to managing dependencies for multiple packages in a single repository, without losing the benefits of having explicit dependencies for each separate package.

Repositories managed with Fiddler contain two kinds of packages:

1. Composer packages defined by a single global composer.json with all external dependencies at the root of the repository.
2. Many Fiddler packages in sub-folders of the project, each with its own fiddler.json, a simplified composer.json file.

Dependencies in Fiddler can be either a third party Composer package that is listed in the composer.json or a Fiddler package contained in the project.

Fiddler's build step generates autoloaders with vendor/autoload.php files for each package with access to the explicitly specified dependencies only.

The following steps are performed by fiddler when building the autoloads:

1. It detects fiddler.json files in subdirectories excluding vendor/ and marks them as roots of packages.
2. It then fetches all composer packages from the locally installed packages.
3. Finally for each package with fiddler.json it generates a vendor/autoload.php file using all the dependencies defined in that package from either other Fiddler or Composer packages.

Fiddler draws inspiration from Google Blaze/Bazel and Facebook Buck implementing a single monolithic repository for whole projects/company. It's the missing piece for the monolithic repository workflow using PHP and Composer.

More details about reasoning on Gregory Szorc's blog:

• On Monlithic Repositories
• Notes from Facebooks Developer Infrastructure at Scale F8 talk

Installation

Composer Plugin (recommended)

Add the composer monorepo plugin to your root composer.json with:

$ composer require beberlei/composer-monorepo-plugin

Now whenever Composer generates autoload files (during install, update or dump-autoload) it will find all sub-directories with fiddler.json files and generate sub-package autoloaders for them.

Standalone (not recommended)

Grab the latest PHAR from the Releases page directly or download the tarball containing it.

Fiddler offers a very simple command line interface for now:

$ php fiddler.phar build

Run this in project root, next to the composer.json file.

Usage

This project assumes you have a single monolithic repository containing multiple packages as well as third-party dependencies using Composer.

You would create a composer.json file in the root of your project and use this single source of vendor libraries across all of your own packages.

This sounds counter-intuitive to the Composer approach at first, but it simplifies dependency management for a big project massively. Usually if you are using a composer.json per package, you have mass update sprees where you upate some basic library like "symfony/dependency-injection" in 10-20 packages or worse, have massively out of date packages and many different versions everywhere.

Then, each of your own package contains a fiddler.json using almost the same syntax as Composer:

{
    "deps": [
        "components/Foo",
        "vendor/symfony/symfony"
    ],
    "autoload": {
        "psr-0": {"Foo\\": "src/"}
    }
}

You can then run fiddler build in the root directory next to composer.json and it will detect all packages, generate a custom autoloader for each one by simulating composer dump-autoload as if a composer.json were present.

Fiddler will resolve all dependencies (without version constraints, because it is assumed the code is present in the correct versions in a monolithic repository).

Package names in deps are the relative directory names from the project root, not Composer package names.

Configuration (fiddler.json)

For each package in your monolithic repository you have to add fiddler.json that borrows from composer.json format. The following keys are usable:

• autoload - configures the autoload settings for the current package classes and files.
• autoload-dev - configures dev autoload requirements. Currently always evalauted.
• deps - configures the required dependencies in an array (no key-value pairs with versions) using the relative path to the project root directory as a package name.
• deps-dev - configures the required dev dependencies

Benefits

1. You can just require "vendor/autoload.php; in every package as if you were using Composer. Only autoloads from the fiddler.json are included, which means all dependencies must be explicitly specified.
2. No one-to-one git repository == composer package requirement anymore, increasing productivity using Google/Facebook development model.
3. No composer.lock/Pull Request issues that block your productivity with multi-repository projects.
4. If you commit vendor/ no dependency on Github and Packagist anymore for fast builds.
5. Much higher Reproducibility of builds.
6. Not yet: Detect packages that changed since a given commit and their dependents to allow efficient build process on CI systems (only test packages that changed, only regenerate assets for packages that changed, ...)