Docker and PHP

Contents of a Docker directory

The following files must be present to use docker-compose:

docker-compose.yml
Dockerfile

docker-compose build will build the image.

Run a basic PHP Docker image

docker run --rm php:7.4-apache-buster php --version

The --rm argument removes the container after it has finished.

Accessing a running container

docker-compose exec [container] bash

Note that the container name is as provided in docker-composer.yml, it is not the container name printed to the command line when you run docker-compose up (however you must pass that name to docker exec).

Enabling Apache modules

Checking which modules are enabled:

apache2ctl -M

Enabling modules (SSL and Rewrite are two common requirements):

RUN a2enmod rewrite ssl

Basic PHP Dockerfile

Build an image and copy in a PHP file:

FROM php:7.4-apache-buster

COPY index.php /var/www/html/

To build the image:

docker build -t phpinfo:latest .

To run the image:

docker run --rm -p 8080:80 phpinfo

Basic PHP Docker Compose

version: "3"
services:
  app:
    image: phpinfo
    container_name: phpinfo
    build:
      context: .
      dockerfile: docker/Dockerfile
    ports:
      - 8080:80
    volumes:
      - .:/var/www

This can be built and run with:

docker-compose up --build -d

-d runs the container as a daemon, and returns the command line immediately.

Dockerfile doesn't have to be in a different directory, but this seems to be something of a convention and perhaps keeps things tidy. By default docker-compose will look for a Dockerfile in the current directory.

Database

Assuming you want to use MariaDB:

version: "3"
services:
    app:
        build: .
        ports:
            - 8080:80
   
    database:
        image: mariadb
        restart: always
        environment: 
            MARIADB_RANDOM_ROOT_PASSWORD: "yes"
            MARIADB_DATABASE: "app"
            MARIADB_USER: "app"
            MARIADB_PASSWORD: "secret"
        ports:
            - 3307:3306

The advantage of adding a port mapping here is that you can connect to the database container from the host, which is handy if you have a graphical MariaDB client such as DBeaver. You can of course also login to the container and run the mysql client on the command line.

Logging into the container using the host:

mysql -u app -D app -h 127.0.0.1 -P 3307 -p

Note: 127.0.0.1 must be used as the host, as MySQL will usually try a socket connection by default if localhost is used (also it may attempt to use ::1, the IPv6 address, which may not work on your setup).

For port mapping from the host, choose something other than the default port (3306), otherwise you will get a clash if MariaDB is running on the host (which it probably will be on a local development machine).

Extensions

PHP extensions can be installed via docker-php-ext-install, e.g. to install the MySQL extension:

RUN docker-php-ext-install pdo_mysql