Install Docker and play with PHP

Docker can be installed free of charge for personal or small-scale usage: https://www.docker.com/products/personal/.

You can install it on Linux, Mac or Windows.

The easiest way, on Windows, is to use Docker Desktop.

One command, a working PHP server​

Start a new console (DOS, Powershell or Linux) and run this:

$ docker run --detach --name step_1_1a -p 80:80 php:8.3-apache▋

Drop an index.php file calling phpinfo() in it (we'll see how, below), surf to http://127.0.0.1:80, and here is a PHP 8.3 server answering on your machine:

http://127.0.0.1:80/

Apache is running, PHP is running, and neither of them has been installed on your computer.

Why Docker images​

• Images are most of the time just plug-and-play: once downloaded, they are ready to use. You will probably add some configuration items but, most of the time, it is not even needed.
• On Docker Hub you'll find a huge number of images for running PHP, PHP+Apache, MySQL and many, many more; all of them completely free, public or private, and you can publish your own. If the very concept of Docker is still fuzzy to you, Docker - Explain me like I'm five is a good, gentle primer.
• The old-fashioned way, before running a web page locally, you first install a web server (e.g., Apache) and the PHP interpreter, then fight to change their versions. Here, the version is a word in a command line.

In this blog post, we will be using the PHP images available at https://hub.docker.com/_/php

Setting it up​

The easiest way, on Windows, is to use Docker Desktop. Once installed, the command shown above is all you need; Docker will, the first time, download PHP 8.3 (including Apache) and, once downloaded, start the image.

Explanation of the arguments used in our docker run --detach --name step_1_1a -p 80:80 php:8.3-apache command

• --detach: by default, docker run executes the container and closes it as soon as the job is finished. If the image were a virus scanner, docker run would run a scan and close the container when the scan is complete. Here, we want to keep our site "listening",
• --name step_1_1a: just for simplicity's sake, let's give our container a name. This is a recommended practice for clearly identifying containers,
• -p 80:80: our PHP+Apache image runs on port 80, so we want to map this "internal" port to port 80 on our computer. This allows us to access the web site.
• php:8.3-apache: the name of the used image. We ask php+apache, version 8.3.

We can see that the PHP image is now present in Docker Desktop, and that an application (a container in Docker terms) is running. We also get both information on the command line, with docker image list and docker container list.

Creating our PHP script​

With the instruction below, we can launch a Linux console and display the contents of the image as if it were a folder on our hard disk:

$ docker exec -it step_1_1a /bin/bash▋

Once in the console, let's quickly create an index.php file and exit the console; we will not need it again.

$ echo "<?php" > index.php
$ echo "phpinfo();" >> index.php
$ exit▋

Back to our browser and... Bingo! Our first Docker instance running a PHP script, i.e. the screenshot shown at the beginning of this article.

Changing the PHP version in one word​

Have you ever tried to change your PHP version if you are using EasyPHP, WAMP or another software program: it is a real pain! With Docker, you change one word.

By going to the page https://hub.docker.com/_/php?tab=tags and searching for -apache images, you'll find every published version. Let's change 8.3 to 8.4 and, for example, use another port (we will use 801 this time).

$ docker run --detach --name step_1_1b -p 801:80 php:8.4-apache▋

$ docker exec -it step_1_1b /bin/bash▋

$ echo "<?php" > index.php
$ echo "phpinfo();" >> index.php
$ exit▋

http://127.0.0.1:801/

No headaches and zero conflicts! We have installed a new version of PHP in seconds, and the two versions are running side by side, each on its own port.

Under the Hood (skip this if you just want to use it)​

Before creating the index.php file, the site answers, but with a Forbidden page:

It works in the sense that something is listening and has responded, but does not display anything, since we haven't set anything up yet: Apache is ready, there's simply no index.php file yet. That's the difference between "the container runs" and "the site works".

Note also that the index.php we created lives inside the container: remove the container and the file goes with it. That's the next step.

Conclusion​

Now let's take it to the next level and synchronize the files on our hard disk with the container: Share data between your running Docker container and your computer, so your code stays on your disk instead of inside the container, then The easiest way to run a PHP script / website, which combines both in a single command.

This same "zero local install" approach works for pretty much any language — I've since applied it to Python, Pascal, Assembly, and Java.