Lavarel shows error SQLSTATE[HY000] [2002] Connection refused

Docker Engine Compose
1

Hello,
The docker-compose.yml file looks like this:

services:
  backend:
    build:
      context: .
      dockerfile: Dockerfile
    container_name: Backend
    ports:
      - "9000:9000"
    environment:
      - APP_ENV=local
      - APP_DEBUG=true
      - DB_CONNECTION=mysql
      - DB_HOST=db
      - DB_PORT=3306
      - DB_DATABASE=laravel_db
      - DB_USERNAME=laravel_user
      - DB_PASSWORD=secret
    depends_on:
      - db
    networks:
      - app_network
    # restart: unless-stopped

  db:
    image: mariadb:latest
    container_name: db
    ports:
      - "3306:3306"
    environment:
      MARIADB_ROOT_PASSWORD: rootsecret
      MARIADB_DATABASE: laravel_db
      MARIADB_USER: laravel_user
      MARIADB_PASSWORD: secret
    volumes:
      - mariadb_data:/var/lib/mysql
      - ./mysql/my.cnf:/etc/mysql/my.cnf
      # - ./p.sql:/docker-entrypoint-initdb.d/p.sql
    networks:
      - app_network
    # restart: unless-stopped

networks:
  app_network:
    driver: bridge

volumes:
  mariadb_data:

And Dockerfile looks like this:

# Stage 1: Composer
FROM composer:2.7 AS composer
WORKDIR /app
COPY . .
RUN composer install \
    --ignore-platform-reqs \
    --no-interaction \
    --no-scripts \
    --optimize-autoloader
# Stage 2: Node.js
FROM node:23-alpine AS node
WORKDIR /app
COPY --from=composer /app .
RUN npm install && npm run build
# Stage 3: PHP-FPM (Fixed)
FROM php:8.3-fpm-alpine
RUN apk add --no-cache \
    bash \
    git \
    libzip-dev \
    libpng-dev \
    && docker-php-ext-install \
    pdo_mysql \
    zip \
    gd \
    bcmath
COPY --from=composer /usr/bin/composer /usr/bin/composer
WORKDIR /var/www/html
COPY --from=composer /app .
COPY --from=node /app/public/build ./public/build
RUN chown -R www-data:www-data /var/www/html/storage \
    && chmod -R 775 /var/www/html/storage \
    && chmod +x /var/www/html/artisan
COPY ./entrypoint.sh /usr/local/bin/
RUN chmod +x /usr/local/bin/entrypoint.sh
ENTRYPOINT ["entrypoint.sh"]
CMD ["php-fpm"]

And entrypoint.sh looks like this:

#!/bin/sh
set -e
# Run Artisan commands (migrations, cache, etc.)
php artisan optimize:clear
php artisan optimize
php artisan view:cache
# Start PHP-FPM (or other services via supervisor if needed)
exec "$@"

The .env file is as follows:

DB_CONNECTION=mysql
 DB_HOST=db
 DB_PORT=3306
 DB_DATABASE=laravel_db
 DB_USERNAME=laravel_user
 DB_PASSWORD=secret

I have imported the p.sql file into the container. When I run the containers, the following error is shown:

# docker logs Backend
In Connection.php line 825:
  SQLSTATE[HY000] [2002] Connection refused (Connection: mysql, SQL: select *
   from `permissions` where `permissions`.`deleted_at` is null)
In Connector.php line 66:
  SQLSTATE[HY000] [2002] Connection refused

Please guide me on how I can troubleshoot this problem.

Thank you.

2

It’s great preparation work for your post, but it’s just too much. Try step by step, check network level first. Check inside a container if you can ping and potentially telnet to port 3306 of the database.