Error: SQLSTATE[HY000] [2002] No such file or directory

Question

I know this type of question as probably been asked a couple of times, but they all have something to do with laravel, in my case this is vanilla php with no framework.

I have a form that that will collect form from users and save it into the database as it should, but i keep getting this error about MYSQL Error: SQLSTATE[HY000] [2002] No such file or directory. Here is my database config file and the file that includes it:

// Database config 
<?php

$host = 'localhost';
$user = 'admin';
$password = '123456';
$db_name = 'nairobi';

$dsn = 'mysql:host='.$host.';dbname='.$db_name;
$options = [ 
  PDO::ATTR_PERSISTENT => true,
  PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
];

    // Create a new PDO instance 
    try {
      $dbh = new PDO($dsn, $user, $password);
    } catch (PDOException $e) {
      print "Error: " . $e->getMessage() . "</br>";
      die();
    }

?>

<?php 
require "./library/Database.php";

if (isset($_POST['submit'])) {

  $first_name = $_POST['first_name'];
  $last_name = $_POST['last_name'];
  $email = $_POST['email'];

  $sql = 'INSERT INTO TABLE members(first_name, last_name, email) 
  VALUES (:first_name, :last_name, :email)';
  $stmt = $dbh->prepare($sql);
  $stmt_value = [
    ':first_name' => $first_name, 
    ':last_name' => $last_name, 
    ':email'=>$email
  ];
  $stmt->execute($stmt_value);
}


?>

Yes, I know the script that process the form is not secure.

Also, I get the following error when I access the page

Fatal error: Uncaught PDOException: SQLSTATE[HY000] [2002] No such file or directory in /var/www/html/library/Database.php:19 Stack trace: #0 /var/www/html/index.php(2): require() #1 {main} thrown in /var/www/html/library/Database.php on line 19

If needed, this is the sql I have gone with

CREATE TABLE IF NOT EXISTS members(
  member_id INT AUTO_INCREMENT NOT NULL PRIMARY KEY,
  first_name VARCHAR(255) NOT NULL,
  last_name VARCHAR(255) NOT NULL,
  email VARCHAR(255) NOT NULL UNIQUE,
  reference_code INT NOT NULL
);

This entire project is also inside a docker container, here is the docker-compose.yml file

version: '3.7'

services:
  php:
    container_name: nairobi_php
    build:
      context: ./
    volumes:
      - './src:/var/www/html'
    depends_on:
      - mysql
    ports:
      - 80:80

  mysql:
    container_name: nairobi_mysql
    image: mysql:8.0
    environment:
      MYSQL_ROOT_PASSWORD: CUeHpADRmZCtnTFGctxp
      MYSQL_DATABASE: nairobi
      MYSQL_USER: admin
      MYSQL_PASSWORD: 123456
    restart: always
    command: --default-authentication-plugin=mysql_native_password
    ports:
      - 3306:3306

  adminer:
    image: adminer
    restart: always
    ports:
      - 8080:8080

Answer 1

I finally solved the problem, thanks @Dlk for your help.

The cause of the problem was because in database.php, I was referring to the host for mysql as localhost instead of the name of the MYSQL service in the docker-compose.yml file. Hence database.php file should look like so :

<?php

$host = 'nairobi_mysql'; // Must be the service name of the database in `docker-compose.yml`
$db_name = 'nairobi';
$user = 'admin';
$pass = '123456';
$charset = 'utf8mb4'; // Always set charset for database
$port = '3306'; 

$dsn = "mysql:host=$host;dbname=$db_name;port=$port;charset=$charset";
$options = [
    PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
    PDO::ATTR_EMULATE_PREPARES   => false,
];
try {
     $pdo = new PDO($dsn, $user, $pass, $options);
} catch (\PDOException $e) {
     throw new \PDOException($e->getMessage(), (int)$e->getCode());
}

?>

which correlates with my docker-compose.yml file

version: '3.7'

services:
  php:
    container_name: nairobi_php
    build:
      context: ./
    volumes:
      - './src:/var/www/html'
    depends_on:
      - mysql
    ports:
      - 80:80

  mysql:
    container_name: nairobi_mysql
    image: mysql:8.0
    environment:
      MYSQL_ROOT_PASSWORD: CUeHpADRmZCtnTFGctxp
      MYSQL_DATABASE: nairobi
      MYSQL_USER: admin
      MYSQL_PASSWORD: 123456
    restart: always
    command: --default-authentication-plugin=mysql_native_password
    ports:
      - 3306:3306

  adminer:
    image: adminer
    restart: always
    ports:
      - 8080:8080