Docker-Composte LEMP : Error: could not find driver

I am trying to create a LEMP in Linux with docker-compose, I have managed to get PHP, NGINX and MySQL to work for me but when connecting to the DB from a php file it returns the exception: could not find driver

This is my docker-compose.yml file

web:
    build: .
nginx:
  image: tutum/nginx
  ports:
    - "80:80"
  volumes:
    - ./sites-available/default:/etc/nginx/sites-available/default
    - ./sites-available/default:/etc/nginx/sites-enabled/default

    - ./logs/nginx-error.log:/var/log/nginx/error.log
    - ./logs/nginx-access.log:/var/log/nginx/access.log

phpfpm:
  image: php:fpm
  ports:
    - "9000:9000"
  volumes:
    - ./public_html:/usr/share/nginx/html

mysql:
  image: mysql:5.7
  command: --default-authentication-plugin=mysql_native_password
  restart: always
  ports:
    - "33061:3306"
  volumes:
    - ./public_html/Model:/docker-entrypoint-initdb.d
  environment:
    MYSQL_DATABASE: tienda
    MYSQL_USER: user
    MYSQL_PASSWORD: user
    MYSQL_ROOT_PASSWORD: root

This is my DockerFile

FROM php:7.2.19-apache-stretch

# PHP extensions
RUN docker-php-ext-install mysqli pdo pdo_mysql

This is the PHP file that connects to the DB

<?php
abstract class TiendaDB {
private static $server = 'localhost';
private static $db = 'tienda';
private static $user = 'root';
private static $password = 'root';
public static function connectDB() {
try {
$connection = new PDO("mysql:host=".self::$server.";dbname=".self::$db.";charset=utf8", self::$user, self::$pass>} catch (PDOException $e) {
echo "No se ha podido establecer conexión con el servidor de bases de datos.<br>";
die ("Error: " . $e->getMessage());
}
return $connection;
}
}

Answer

I have managed to solve it, I have added the Dockerfile file that @β.εηοιτ.βε and it gave me another error so I have done it all again and it has worked for me:

Folder Structure:

DOCKER_LEMP
├── app                 # All of your php file should be placed here, treat it like /var/www directory
│   └── index.php       # Default index file
├── database            # The database is saved here
├── nginx               # This folder contains nginx specified configuration
│   └── default.conf    # Default configuration file
├── php                 # Contains custom PHP7-fpm docker configuration
│   └── Dockerfile      # Docker configuration file for PHP container
├── docker-compose.yml  # Docker configuration for this project
└── readme.md           # Description for this project

Nginx config:

server {
    listen 80;
    index index.php index.html;
    server_name localhost;
    error_log  /var/log/nginx/error.log;
    access_log /var/log/nginx/access.log;
    root /app;

    location ~ .php$ {
        try_files $uri =404;
        fastcgi_split_path_info ^(.+.php)(/.+)$;
        fastcgi_pass php:9000;
        fastcgi_index index.php;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_path_info;
    }
}

docker-compose.yml config

version: '3'

networks:
    LEMP:

services:
    nginx:
        image: nginx:stable-alpine
        container_name: LEMP_nginx
        ports:
            - "80:80"
        volumes:
            - ./app:/app
            - ./nginx/default.conf:/etc/nginx/conf.d/default.conf
        depends_on:
            - php
        networks:
            - LEMP

    mysql:
        image: mysql:latest
        container_name: LEMP_mysql
        volumes:
            - ./database:/var/lib/mysql:rw
        ports:
            - "3306:3306"
        depends_on:
            - nginx
        environment:
            - MYSQL_ROOT_PASSWORD=admin123
        networks:
            - LEMP

    php:
        # image: php:7-fpm-alpine
        build: ./php
        container_name: LEMP_php
        volumes:
            - ./app:/app
        ports:
            - "9000:9000"
        networks:
            - LEMP

    phpmyadmin:
        image: phpmyadmin/phpmyadmin
        container_name: LEMP_phpmyadmin
        ports:
            - "8000:80"
        environment:
            PMA_ARBITRARY: 1
        depends_on:
            - mysql
        networks:
            - LEMP

Dockerfile config:

FROM php:7-fpm-alpine
RUN docker-php-ext-install mysqli pdo pdo_mysql