Docker PHP MySQL connection refused - php

Question

I am trying to run a site using multiple container configuration - one for apache, second for mysql and third for myadmin. Everything starts fine, setup runs smooth but when I try to run a PHP application I get mysqli::__construct(): (HY000/2002): Connection refused in system/libraries/drivers/Database/Mysqli.php [54] error.
It seems that there's something wrong with the connection settings but I checked the site through PHP MyAdmin running on separate container and copied the db host IP from there just to be sure. How can I/should I connect from PHP container to MySQL db?
Here's my docker-compose.yml file:
version: '3'
services:
web:
build:
context: ./etc/php
args:
- APP_HOST=${APP_HOST}
- MYSQL_USER=${MYSQL_USER}
- MYSQL_PASSWORD=${MYSQL_PASSWORD}
- MYSQL_PORT=${MYSQL_PORT}
- MYSQL_DATABASE=${MYSQL_DATABASE}
ports:
- ${APP_PORT}:80
- ${APP_PORT_SSL}:443
volumes:
- ./var/bin/:/tmp/bin/
- ./app/:/var/www/html/
- ./log/apache2/:/var/log/apache2/
- ./etc/php/conf/:/usr/local/etc/php/conf.d/
environment:
- VIRTUAL_HOST=${VIRTUAL_HOST}
db:
build:
context: ./etc/mysql
args:
- MYSQL_DATABASE=${MYSQL_DATABASE}
- MYSQL_USER=${MYSQL_USER}
- MYSQL_PASSWORD=${MYSQL_PASSWORD}
- MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD}
- DUMP_FILE=${DUMP_FILE}
volumes:
- ./etc/mysql/conf:/etc/mysql/conf/conf.d
- ./data:/var/lib/mysql
- ./log/:/var/log/
ports:
- "${MYSQL_PORT}:3306"
phpmyadmin:
image: phpmyadmin/phpmyadmin
environment:
MYSQL_ROOT_PASSWORD: root
ports:
- ${MYADMIN_PORT}:80
environment:
- VIRTUAL_HOST=phpmyadmin.localhost
And the .env with variables:
VIRTUAL_HOST=foo.local
APP_PORT=80
APP_PORT_SSL=443
MYADMIN_PORT=8081
APP_HOST=foo.local
ADMIN_APP_HOST=admin-foo.local
MYSQL_DATABASE=foo_local
MYSQL_USER=root
MYSQL_HOST=172.26.0.2
MYSQL_PASSWORD=root
MYSQL_ROOT_PASSWORD=root
MYSQL_PORT=3306
Oh, and here's the code I try to run:
$this->link = $socket ? new mysqli(null, $user, $pass, $database, $port, $socket) :
new mysqli($host, $user, $pass, $database, $port);
Output of echo $host.'<br>'.$user.'<br>'.$pass.'<br>'.$database.'<br>'.$port.'<br>'.$socket; is following:
172.26.0.2
root
root
hq_local
3306

Answer 1

check your container IP with a docker inspect [container name] but write IP in a file is not very good. Replace IP by name of your db container.

Answer 2

You can always use host.docker.internal as IP, therefore you can use something like this:
$db = new \PDO('mysql:host=host.docker.internal;port=3306;dbname=db', 'root', 'pass');

Answer 3

Check out the /etc/hosts configuration inside your web service container for container linkage.
docker exec -it <container_name> cat /etc/hosts
Docker network won't be assigning the same IP to db container that you have specified for the MYSQL_HOST all the time. So better ti use the conatiner name in order to connect from web container.
Also, based on the context that you have specified in docker-compose.yml, try this:
new mysqli('etc/mysql', $user, $pass, $database, $port);

Answer 4

all you need to do is to specify the value of the host in mysql the official environment variable is MYSQL_ROOT_HOST: localhost if you do not do that then the host becomes the name of the service which in your case it is db.

Answer 5

Put everything in .env file and call the environment variables from there. Don´t worry about changing code if you write it as:
$mylink = mysqli_connect(
env("DB_HOST"),
env("DB_USER"),
env("DB_PASS"),
env("DB_NAME"),
env("DB_PORT",3306)
)