I was playing with Kubernetes during last weekend, but the project was just a small PHP file with phpinfo() function call, no big deal.

Today my colleague asked me to guide him a bit on Docker, because he’d like to try it with a real world example: Developing a Symfony project. So let’s take a look at this!

Symfony uses Composer to manage its dependencies and scripts, namespaces,.. via a file named composer.json. Dependencies will be download to a directory called vendor

Focus on development, we want to create a ready configured & isolated environment, so anyone can clone the repository and run the application easily. So we’re gonna use 3 containers:

MySQL, with mounted volume for data persistent

PHP-FPM, with mounted volume for application’s code

NGINX, with mounted volumes for configurations, logs, and share mounted volume with PHP-FPM for application’s assets

We will also need to use some environment variables for containers’ parameters, like database credentials, application secret key,…

We’re gonna use Docker-Compose to put configurations and run all containers.

Project │ ├── docker-compose.yml │ ├── database/ │ ├── Dockerfile │ └── data/ │ └── php-fpm/ │ └── Dockerfile │ ├── nginx/ │ ├── Dockerfile │ └── nginx.conf │ └── logs/ └── nginx/

MySQL Database

Let’s just create a MariaDB container

FROM mariadb:latest CMD ["mysqld"] EXPOSE 3306

We use MariaDB official image Run mysqld to start the server Expose port 3306 for database connection

PHP-FPM

With PHP-FPM container, we’d like to install dependencies and run database migrations at start. So we need to install the PDO MySQL extension, then composer, and then Symfony migration script.

However, it could be a problem, if we run the migration before the MySQL server is ready!

With Docker-compose, we can specify a depends_on configuration to tell it wait for another container. But it doesn’t mean Docker-compose will wait until the MySQL server is ready, it only waits until the MySQL container is up. Fortunately, with the help from wait-for-it script, we can try to wait until the MySQL container’s port 3306 is Open (Or you can even try to wait until you can connect to the MySQL using credentials).

FROM php:fpm-alpine COPY wait-for-it.sh /usr/bin/wait-for-it RUN chmod +x /usr/bin/wait-for-it RUN apk --update --no-cache add git RUN docker-php-ext-install pdo_mysql COPY --from=composer /usr/bin/composer /usr/bin/composer WORKDIR /var/www CMD composer install ; wait-for-it database:3306 -- bin/console doctrine:migrations:migrate ; php-fpm EXPOSE 9000

We use PHP-FPM offical image Copy wait-for-it script into the container Allow execution for wait-for-it Add git for dependencies installation Install PHP PDO MySQL Take composer file from Composer official image Set working dir to /var/www Install dependencies, then wait until the MySQL container is Online to run migration script. Finally, run php-fpm to start the server Expose PHP-FPM port (9000)

NGINX

This part is a bit complex, we’re gonna crate NGINX configuration file, the PHP-FPM proxy, and a separated file for default NGINX site.

First the Dockerfile definition

FROM nginx:alpine WORKDIR /var/www CMD ["nginx"] EXPOSE 80

As above, we use NGINX official image Set working dir to /var/www, the same directory with PHP-FPM since we’re gonna share this with a mounted volume Start nginx Expose the port 80 for web

Now, an NGINX server configuration

user nginx; worker_processes 4; daemon off; error_log /var/log/nginx/error.log warn; pid /var/run/nginx.pid; events { worker_connections 1024; } http { include /etc/nginx/mime.types; default_type application/octet-stream; access_log /var/log/nginx/access.log; sendfile on; keepalive_timeout 65; include /etc/nginx/conf.d/*.conf; include /etc/nginx/sites-available/*.conf; }

An NGINX – PHP-FPM configuration

upstream php-upstream { server php-fpm:9000; }

And an NGINX site’s configuration

server { listen 80 default_server; listen [::]:80 default_server ipv6only=on; server_name localhost; root /var/www/public; index index.php index.html index.htm; location / { try_files $uri $uri/ /index.php$is_args$args; } location ~ \.php$ { try_files $uri /index.php =404; fastcgi_pass php-upstream; fastcgi_index index.php; fastcgi_buffers 16 16k; fastcgi_buffer_size 32k; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; fastcgi_read_timeout 600; include fastcgi_params; } location ~ /\.ht { deny all; } }

Docker-Compose configuration

We have 3 container definitions, now we just need to setup a Docker-compose configuration to connect all togethers:

version: '3' services: database: build: context: ./database environment: - MYSQL_DATABASE=${DATABASE_NAME} - MYSQL_USER=${DATABASE_USER} - MYSQL_PASSWORD=${DATABASE_PASSWORD} - MYSQL_ROOT_PASSWORD=${DATABASE_ROOT_PASSWORD} ports: - "3306:3306" volumes: - ./database/init.sql:/docker-entrypoint-initdb.d/init.sql - ./database/data:/var/lib/mysql php-fpm: build: context: ./php-fpm depends_on: - database environment: - APP_ENV=${APP_ENV} - APP_SECRET=${APP_SECRET} - DATABASE_URL=mysql://${DATABASE_USER}:${DATABASE_PASSWORD}@database:3306/${DATABASE_NAME}?serverVersion=5.7 volumes: - ../src:/var/www nginx: build: context: ./nginx volumes: - ../src:/var/www - ./nginx/nginx.conf:/etc/nginx/nginx.conf - ./nginx/sites/:/etc/nginx/sites-available - ./nginx/conf.d/:/etc/nginx/conf.d - ./logs:/var/log depends_on: - php-fpm ports: - "80:80"

And a sample environment variables:

DATABASE_NAME=symfony DATABASE_USER=appuser DATABASE_PASSWORD=apppassword DATABASE_ROOT_PASSWORD=secret APP_ENV=dev APP_SECRET=24e17c47430bd2044a61c131c1cf6990

Symfony

Let’s proceed to the Symfony installation:

$ symfony new src

Play time

Everything is setup correctly! Let’s play with our containers!

$ docker-compose up

When those containers are ready, you can start to open http://localhost, you will see a Symfony 5 welcome screen. Everything works perfectly, have fun!

I’ve create a repository for all the files we talked above https://gitlab.com/martinpham/symfony-5-docker