Use Composer like a Pro - the Dependency Manager for PHP

Created April 21, 2021


Composer is without the go to dependency manager for PHP. Composer is a command line tool that you can use to install packages to your projects and also update and manage existing packages.

If you are coming the JavaScript world you could consider composer as the dependency manager for PHP similar to NPM for JavaScript. Or if you have experience with Java, you could make the same analogy with Maven.

You will see an interactive Bash terminal pop up at the bottom of your screen where you can run the composer commands specified in this tutorial.

Composer has a wide variety of open-source packages available at Packagist.

If you never used composer I would recommend going through this quick article first here: Composer. Why, What, and How?

In this tutorial you will learn all of the essential composer commands and start using composer like a pro!


If you are planning to use the interactive terminal, you can run the following commands to get Composer installed.

As the interactive terminal is based on Ubuntu, we will use apt to install PHP first:

apt update -y
apt install php*-cli
php -r "copy('', 'composer-setup.php');"
php -r "if (hash_file('sha384', 'composer-setup.php') === '756890a4488ce9024fc62c56153228907f1545c228516cbf63f885e036d37e9a59d27d63f46af1d4d07ee0f76181c7d3') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
php composer-setup.php
php -r "unlink('composer-setup.php');"
mv composer.phar /usr/bin/composer
composer --version


Composer version 2.0.12 2021-04-01 10:14:59

The above will work on any Ubuntu or Debian based system.

In order to install composer on your PC, you can follow the steps from the official documentation:

Using Composer

Now that we have composer installed, let's go ahead and learn some essential composer commands!

Adding Composer to a project

If you are starting a new PHP project, you can include Composer by running the following command:

composer init

This command will guide you through creating your composer.json config and you will be prompted with a series of questions about your project.

You can follow the prompt and add the necessary information to your project.

At the end you will be prompted with a preview of your composer.json file and you can confirm if you want to have it generated.

Searching for packages

You can search for PHP packages directly via the official Composer package repository here:

Instead you could also use the composer search command to search for packages directly via your terminal:

composer search laravel

Installing a composer package

Let's go ahead and install the following Hello World package! To do so you can run the following command:

composer require ehime/hello-world

Composer will then download the ehime/hello-world package from the Packagist repository to your local machine or the interactive terminal.

You can use the ls command to see the content of the current directory:

ls -lh

You will see a directory in there called vendor where all of the composer packages will be stored at. To see the content of the Hello World package, run the following command:

ls -lah vendor/ehime/hello-world/

Note: you should never change the content of the vendor folder manually as all of your changes will be lost the next time you run composer update.

If you were now to check the composer.json file you will see that under the require section, you will see the hello-world package listed:

    "require": {
        "ehime/hello-world": "^1.0"

The composer install command

As we now have the hello-world dependency listed in our composer.json we can actually completely delete the vendor folder and then run composer install which will check the composer.json file and install all of the required dependecies. Let's give it a try!

rm -r vendor
ls -lh
composer install
ls -lh

As you can imgine this is very handy as you can define all of your dependencies in the composer.json file, share it with your colleagues and they could just run composer install and have all of the dependencies installed.

In most cases the vendor directory would not be checked into git as well.

Using the installed packages

If you are using a framework like Laravel, the packages will be auto loaded without you having to require the 'vendor/autoload.php' file.

However if you are not using a framework you could include all of the packages so that you would have all of the classes and functions provided by the packages in your PHP prject, you would need to add the following:

require 'vendor/autoload.php';

So in our cases, if we wanted to use the SayHello class for the Hello World package, we could do the following:

require 'vendor/autoload.php';

use HelloWorld\SayHello;

echo SayHello::world() . "\n";

Rundown of the file:

Of course this is a very simple package, but in most cases, you can follow the instructions from the official documentation of each specific package and how to use it.

Understanding the composer.lock file

Thanks to the composer.lock file composer would know the exact package verions that should be installed.

In the composer.lock file the exact verions of all packages is being recorded including the exact commit ID associated with the package version.

If you were to inspect the composer.lock file and search for the hello-world package, , you will be able to see all that information:

            "name": "ehime/hello-world",
            "version": "1.0.5",
            "source": {
                "type": "git",
                "url": "",
                "reference": "b1c8cdd2c11272d8c5deec7816e51fa5374217c1"

The reference part is the commit ID. That way composer will know the exact versions of the specific packages that should be installed so that your project does not break every time you run composer install.

Thanks to the composer.lock file you can ensure that all of your team members are running the exact same version of each package.

Updating packages

To get a list of any outdated packages included in your project you can run the following command:

composer outdated

To update the a specific package, you can modify the composer.json file and adjust the package version that you want to use. After changing the version, you can run the following command to actually update the packages:

composer update

Composer will then check the composer.json file and update the packages that you've increased the version for.

Useful Composer commands

Here is a short cheatsheet of popular composer commands that you might use on daily basis:

composer init
composer install
composer required name_of_package_here
composer require --dev name_of_package_here

Note: This is useful when including packages that could be used for debuging for example

composer show
composer outdated
composer update

Note: this will also update your composer.lock file

composer remove package_name_here

For more information on how to remove packages, check out this post here:

How to remove a package from Laravel using composer?


Hope that this was helpful! As a next step I would recommend going through this video course on how to build a Laravel package which will take your composer knowledge to the next level!

Creating a Laravel Package

Also if you are using Git, make sure to exclude the vendor folder from your project. You can do that by following the steps here:

How to exclude files from your Git project using .gitignore?