Symfony; SQLSTATE[HY000] [2002] No such file or directory while using 127.0.0.1 as database_host - mysql

Question

The full error is Doctrine\DBAL\Exception\ConnectionException: An exception occurred in driver: SQLSTATE[HY000] [2002] No such file or directory in /app/vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/AbstractMySQLDriver.php on line 113, but that's too long for the title.
I'm trying to set up a Symfony project locally, but I'm struggling to get the database connection to work. My parameters.yml looks as follows
parameters:
database_host: 127.0.0.1
database_port: 3306
database_name: database_name
database_user: username
database_password: password
I've been googling this issue a lot and most people seem to solve the issue by changing database_host from localhost to 127.0.0.1, but this doesn't work for me. The app itself runs via Docker, but I've set up the database connection once via Brew and once with a MySQL server for Mac. In both cases I can connect via the command line and with SequelPro/TablePlus, but whenever I try to access the website through the browser I get the "No such file or directory" error.
I've also tried multiple ways of setting up a Docker MySQL container, but can't get it to work. My docker-compose.yml looks like this;
nginx:
build: nginx
ports:
- "8080:80"
links:
- php
volumes:
- ../:/app
php:
build: php-fpm
volumes:
- ../:/app
working_dir: /app
extra_hosts:
- "site.dev: 172.17.0.1"
services:
db:
image: mysql:5.7
restart: always
environment:
MYSQL_DATABASE: 'database_name'
MYSQL_USER: 'username'
MYSQL_PASSWORD: 'password'
MYSQL_ROOT_PASSWORD: 'password_root'
ports:
- '3306:3306'
expose:
- '3306'
volumes:
- my-db:/var/lib/mysql
But whenever I run docker-compose up -d I get the error Unsupported config option for services: 'db'.
Another attempt was adding
mysql:
image: mysql:latest
volumes:
- mysql_data:/var/lib/mysql
environment:
- MYSQL_ROOT_PASSWORD='password'
- MYSQL_DATABASE='database_name'
- MYSQL_USER='username'
- MYSQL_PASSWORD='password'
To the docker-compose file, and while it does build the mysql image, I can't seem to connect to it with SequelPro/TablePlus. I ran docker-inspect on the container to get the IP (172.17.0.3), but can't seem to get access to it. I can exec into it, login using mysql -u root and create the required user and database, but then I'm still struggling to actually connect to it.
Running docker ps does show the sql container running btw;
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b6de6030791d docker_nginx "nginx -g 'daemon of…" 19 minutes ago Up 14 minutes 0.0.0.0:8080->80/tcp docker_nginx_1
f26b832bb005 docker_php "docker-php-entrypoi…" 19 minutes ago Up 14 minutes 9000/tcp docker_php_1
6c2a9e657435 mysql:latest "docker-entrypoint.s…" 19 minutes ago Up 14 minutes 3306/tcp, 33060/tcp docker_mysql_1
I also thought it might be an issue with changes to the parameters.yml file not properly syncing with the container as I'm using Mac (at my old workplace we had to use docker-sync to make sync changes between our dev environment and the actual container), but when inspecting the container itself using exec I can see the changes in the parameters.yml file.
Could the issue be it trying to connect to a mysql server running outside the Docker container? I'm still very new to Docker so I wouldn't be surprised if that's the mistake. Any tips are appreciated 'cause I'm at a dead end.

Answer 1

Your docker-compose file looks wrong to me, try below docker-compose file.
I removed the links, network is much easier.
version: '3'
services:
nginx:
build: nginx
ports:
- "8080:80"
networks:
- backend
volumes:
- ../:/app
php:
build: php-fpm
volumes:
- ../:/app
working_dir: /app
networks:
- backend
extra_hosts:
- "site.dev: 172.17.0.1"
db:
image: mysql:5.7
restart: always
environment:
MYSQL_DATABASE: 'database_name'
MYSQL_USER: 'username'
MYSQL_PASSWORD: 'password'
MYSQL_ROOT_PASSWORD: 'password_root'
networks:
- backend
ports:
- '3306:3306'
volumes:
- ./my-db:/var/lib/mysql
networks:
backend:
driver: bridge
then use database_host: db in php file.
I would diagnose
Check docker logs in the mysql container => no errors
Login to the mysql container and login to mysql => no errors
Login to mysql from the host (mysql -u username -p since you are mapping to 3306 port of the host)
Make sure mysql.cnf doesn't block connect from outside(check
bind-address in the mysql configuration if it 127.0.0.1 the its only
allow to connect form locally, i would for now make it 0.0.0.0 or
commented that line if exists)
mysqld --verbose --help => you will see all options
mysqld --verbose --help | grep bind-address=> check the bind-address
Make sure the user i tried to login has enough privileges to
connect(SELECT user,host FROM mysql.user;) check your user can
connect from docker network => 172.* or anywhere=> %

Answer 2

I think your issue is with your parameters.yml:
parameters:
database_host: 127.0.0.1
When you run compose, MySQL and PHP will run in their own containers which will have their own IPs: 127.0.0.1 or localhost from the php won't be able to connect to the db container. It's like you deployed PHP on a virtual machine A and MySQL to another virtual machine B, but you try to access MySQL from machine A by using localhost where you should specify machine B IP or hostname.
With Docker Compose the internal DNS will resolve the service name to it's container, so you can use something like:
parameters:
# name of the service in compose should be resolved
database_host: db
The error SQLSTATE[HY000] [2002] No such file or directory may be caused when the client tries to read MySQL socket usually present at /var/lib/mysql/mysql.sock which is probably not present in your PHP container.