Cannot not connect to database server within docker-compose (php and MariaDB) - php

Question

I've built a docker-compose file that creates 2 services (PHP and MariaDB). Somehow I cannot connect to the database from the PHP service: Within the PHP service, a Laravel-app is running.
The error message (redirect is a table within the database):
SQLSTATE[HY000] [2002] Connection refused (SQL: select * from redirects)
All env-variables should be correct.
Here is my docker-compose.yml:
version: "3.7"
services:
faaren_backend:
image: php:alpine
container_name: FAA-Backend
volumes:
- "./:/faaren_backend"
working_dir: /faaren_backend
command: "php artisan serve --host=0.0.0.0 --port=8000"
ports:
- 8000:8000
build:
context: docker/php
dockerfile: dev.Dockerfile
faaren_database:
image: mariadb
container_name: FAA-Database
ports:
- "3306:3306"
environment:
MYSQL_ALLOW_EMPTY_PASSWORD: 1
MYSQL_DATABASE: ${DB_DATABASE}
volumes:
- "faa-db-data:/var/lib/mysql/data"
volumes:
faa-db-data: {}
My dev.Dockerfile
FROM php:7.3-fpm
RUN apt-get update
RUN apt-get update && apt-get install -y libzip-dev \
&& docker-php-ext-install zip
RUN apt-get update && apt-get install -y libmagickwand-dev --no-install-recommends && rm -rf /var/lib/apt/lists/*
RUN pecl install imagick
RUN docker-php-ext-enable imagick
RUN apt-get install $PHPIZE_DEPS && \
pecl install xdebug && docker-php-ext-enable xdebug && \
docker-php-ext-install pdo_mysql pcntl
RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer
VOLUME /faaren_backend
And finally my .env-file:
DB_CONNECTION=mysql
DB_HOST=faaren_backend
DB_PORT=3306
DB_DATABASE=faaren_db
DB_USERNAME=root
DB_PASSWORD=
Mostly I've followed this tutorial: https://medium.com/swlh/laravel-with-docker-compose-de2190569084

Answer 1

You need change your docker database host:
DB_CONNECTION=mysql
DB_HOST=faaren_database <-- edit
DB_PORT=3306
DB_DATABASE=faaren_db
DB_USERNAME=root
DB_PASSWORD=
And in docker-compose.yml faaren_backend section add:
depends_on:
- faaren_database
Hope it's help.

Answer 2

Looks like you deal with a race condition. You need to use depends_on directive to control startup order and use wait script to make sure that service ready to accept connections:
version: "3.7"
services:
faaren_backend:
image: php:alpine
container_name: FAA-Backend
volumes:
- "./:/faaren_backend"
working_dir: /faaren_backend
command: entrypoint.sh
ports:
- 8000:8000
depends_on:
- faaren_database
build:
context: docker/php
dockerfile: dev.Dockerfile
faaren_database:
image: mariadb
container_name: FAA-Database
ports:
- "3306:3306"
environment:
MYSQL_ALLOW_EMPTY_PASSWORD: 1
MYSQL_DATABASE: ${DB_DATABASE}
volumes:
- "faa-db-data:/var/lib/mysql/data"
volumes:
faa-db-data: {}
There are a bunch of ways to check service availability, sometimes wait-for-it can be really handy. In the example below used netcat(you need to install it into the container).
Also, it'a good idea to put a script into a separated file:
entrypoint.sh
#!/usr/bin/env bash
until nc -w 1 -z faaren_database 3306; do
>&2 echo "Mysql is unavailable - sleeping"
sleep 1
done
sleep 10
>&2 echo "Mysql is up - executing command"
php artisan serve --host=0.0.0.0 --port=8000
UPDATE: Specify correct DB_HOST how Dmitry suggested as well.