Can't connect to between mysql container and php in docker - php

Question

Trying to connect to mysql 8 (mysql:latest) from a php:latest image (without apache or nginx) and I'm getting this annoying error:
Fatal error: Uncaught PDOException: SQLSTATE[HY000] [2002] Connection refused in /src/conn.php:5
Stack trace:
#0 /src/conn.php(5): PDO->__construct('mysql:host=data...', 'root', '12345678')
#1 {main}
thrown in /src/conn.php on line 5
I've looked for +20 solutions here on stackoverflow but none of them was able fix my problem. I can connect without a problem using mysql workbench or DataGrid using the following credentials:
server: localhost user: root pass: 12345678
But any configuration I use on the php image I can't make them connect with each other.
My docker-compose file:
version: '3'
services:
composer:
container_name: composer
networks:
- backend
image: composer
volumes:
- .:/app
command: install
database:
container_name: mysql
networks:
- backend
image: mysql:latest
volumes:
- ./database/mysqldata:/var/lib/mysql
command: --default-authentication-plugin=mysql_native_password
environment:
MYSQL_ROOT_PASSWORD: 12345678
MYSQL_DATABASE: testdb
ports:
- "3306:3306"
php:
build:
context: .
container_name: php
networks:
- backend
image: php:apache
links:
- database
env_file:
- .env
volumes:
- .:/
command:
php /src/conn.php
depends_on:
- composer
- database
networks:
backend:
My conn.php:
<?php
$db = new PDO('mysql:host=database;dbname=testdb', 'root', '12345678');
What I did until now to try to fix the problem:
Change conn.php host to 127.0.0.1
Change conn.php host to localhost
Tried to use mysqli (got also connection refused)
Tried another php images (with apache, nginx etc)
Tried to use mysql as a host
PS: I'm using docker for mac
After 5 hours of research I really don't know what else to do and as I'm not a docker expert, would appreciate any help to point me the direction of the fix.
Thank you!

Answer 1

In your case, you can't connect to mysql via localhost or 127.0.0.1. If you connect like this. It call to localhost inside php container. But there is no mysql install in your php container.
You must connetc via container name. Or docker inspect you mysql container and get the container IP. For example with your docker-compose
database:
container_name: mysql
Now your mysql database host is mysql - container name instead localhost

Answer 2

Was able to find the solution. Turns out I need to wait for mysql service to be available before I start the php script. So I used the wait-for-it solution and did this on docker-compose:
command: >
bash -c "chmod +x /docker/./wait-for-it.sh
&& /docker/./wait-for-it.sh database:3306 -- echo 'database is up'
&& php phpscript.php"
Thank you for the help