Working with PHP dependencies in multiple repositories

How to synchronize changes between two dependent PHP code bases in two Git repositories.

Imagine yourself working on a PHP code base distributed between two or more Git repositories, for example a library and an application part. Ideally, the two repositories should be independent, but sometimes that lofty goal can’t be achieved. And having two repositories open in your editor and doing git commit, git push, composer update all the time becomes tedious. This article shows how to work faster with two dependent PHP code bases.

Edit composer.json to use local repository

Regardless if your library is on packagist or in a GitHub repository, put something like this in the composer.json file of your application:

    "repositories": [
            "type": "path",
            "url": "../relative/path/to/your/library"

When you run composer install, composer will try to create a symbolic link to the library. That means when you change the library, the change will be immediately available in the code of the application. If composer can’t create a symlink created, you’ll need to run composer update your/library for every change you make in the library.

If the composer.json of your library does not have a version entry that matches the version in the requirements of the application, you can change the require entry in the composer.json of your application to "your/library": "@dev".

When you’re finished coordinating your code bases, create a new release of your library and remove the path repository from the composer.json of your application.

The composer-based approach only works, if the PHP environment supports symbolic links. If you’re using a virtual machine or a Docker container, the target of the symbolic link may be outside of the file system that’s exposed from your host machine to the guest VM/container. In these cases you can to mount the dependency into the vendor folder instead.

Mounting the dependency into a Docker container

Docker allows you to mount directories into your image. The mounts will overlay the existing content. To overlay the contents of the vendor/your/library in the docker container, you add the parameter

-v /path/to/your/library:vendor/your/library

to your docker command.

If you’re using docker-compose, add the directory to your volumes list:

        image: php:7.1-fpm-alpine
            - .:/code
            - /path/to/your/library:code/vendor/your/library

Make sure that when you run composer commands, you’re not running them inside the container in which you mounted the library. Running them in a separate container will change only the original vendor directory on your host machine.