Installing PHP Packages with Docker and Composer

Package management is a method for importing code (often from open source libraries) and keeping dependencies up to date in a software development project. In PHP, we have a couple ways to manage packages, but the dominant choice for modern PHP development is Composer.

While you can install PHP and Composer on your local machine directly, in this tutorial we’ll use Docker, which allows us to run PHP and Composer scripts without configuring either on our system directly. If you haven’t already, you should install Docker for your operating system.

Creating a PHP Timer Script

We are going to write a PHP script that sleeps for between 1 and 3 seconds, then tells us how long it waited. It’s very simple using the PHP Timer package, but we’ll need to import it.

composer.json

Create a new file called composer.json and add the following to it:

{
    "require": {
        "phpunit/php-timer": "^1.0.9"
    }
}

This tells Composer about our dependencies — in this case, just one package — when we run the install command.

Installing the Dependencies

Next, we will install the dependencies using the official Composer Docker image:

docker run --rm -v $(pwd):/app composer/composer:latest install

Let’s look at this docker command and see what’s going on:

• docker run is Docker’s command to run a command within a new container. There are a lot of options that you can pass in, so be sure to read the documentation.
• --rm tells Docker to “remove” the container after the command is run. Alternatively, you can save the container and name it to run it again.
• -v $(pwd):/app is telling Docker to mount a volume. You typically pass in a path to a folder on your root directory, a colon, and then a path to the folder in the container. Here we are mounting the current directory (along with the composer.json file we created) into a container. This mounting goes both ways, so we will also see the /vendor folder created when Composer runs.
• composer/composer:latest is the actual image we’re using for this container. This will install the packages for PHP 7, but Composer also has images for older versions of PHP.
• install is the Composer command that is going to be run. You can also do update or dump-autoload in this same manner.

Now all the dependencies are installed in a new /vendor folder, but we still have to import them and write our PHP script.

The PHP Script

Our PHP script imports the dependencies that are included in Composer’s vendor/autoload.php file, starts a timer, waits between 1 and 3 seconds, then outputs the final time that the script took to run. This part of the tutorial works the same way whether you use Docker or not. This file should be named index.php:

<?php require('vendor/autoload.php');
\PHP_Timer::start();
sleep(rand(1, 3));
$time = \PHP_Timer::stop();
print \PHP_Timer::secondsToTimeString($time);

Running the PHP Script

Finally, we just need to run the new PHP script we created in another Docker container. This is covered in more detail in our tutorial on running PHP scripts in Docker, but the final command should be:

docker run --rm -v $(pwd):/app -w /app php:cli php index.php

You should see either 1 second, 2 seconds, or 3 seconds on your terminal output.

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