Can't connect to Postgres database using PHP PDO and Docker - php

Question

I am running a Docker app that is built on three images: php:7.4-fpm, nginx:stable-alpine and postgres:alpine.
I was previously attempting to use the image php:7.4-fpm-alpine, but apparently it does not come with the Postgres PDO driver, which was causing a could not find driver error. This post explains more about that, and how to fix it. I followed the steps in that post, including creating a Dockerfile for my PHP FPM service (though I did not create a PHP CLI service), and that remedied my driver issues. However, I am now getting the following error when I try to connect to my PSQL database using PDO:
SQLSTATE[08006] [7] could not connect to server: Connection refused Is the server running on host "localhost" (127.0.0.1) and accepting TCP/IP connections on port 6432?
I know my database is running (on port 6432) because I can access it from my terminal and from Positco, and have created tables after my Docker app was created. I also tried to connect to a database on port 5432 (through which my Postgres desktop app is running), but that did not work either. I also tried to restart my Postgres container, but that did not help.
Here is my PHP:
class Database {
private $connection;
private static $options = array(
PDO::ATTR_EMULATE_PREPARES => FALSE,
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
);
public function __construct() {
try {
$dsn = 'pgsql:host=localhost;port=6432;dbname=db_my_test_app';
$username = 'root';
$password = 'secret';
$connection = new PDO($dsn, $username, $password, self::$options);
$this->connection = $connection;
return $connection;
} catch (PDOException $e) {
exit($e->getMessage());
}
}
}
$database = new Database();
...and my docker-compose.yml file:
version: '3'
networks:
my_test_app:
services:
# nginx
nginx-service:
image: nginx:stable-alpine
container_name: nginx-container
ports:
- "8080:80"
volumes:
- ./app:/var/www/project
- ./nginx/default.conf:/etc/nginx/conf.d/default.conf
depends_on:
- php-fpm-service
- postgres-service
networks:
- my_test_app
# php
php-fpm-service:
build:
context: .
dockerfile: ./php-fpm/Dockerfile
container_name: php-fpm-container
ports:
- "9000:9000"
working_dir: /var/www/project
volumes:
- ./app:/var/www/project
networks:
- my_test_app
# postgres
postgres-service:
image: postgres:alpine
container_name: postgres-container
ports:
- "6432:5432"
volumes:
- ./postgres:/var/lib/postgresql/data
restart: always
environment:
POSTGRES_USER: root
POSTGRES_PASSWORD: secret
POSTGRES_DB: db_my_test_app
networks:
- my_test_app
...and the PHP service Dockerfile (from the aforementioned site):
FROM php:7.4-fpm
RUN apt-get update && apt-get install -y libpq-dev
RUN docker-php-ext-install pdo pdo_pgsql pgsql
RUN ln -s /usr/local/etc/php/php.ini-production /usr/local/etc/php/php.ini
RUN sed -i -e 's/;extension=pgsql/extension=pgsql/' /usr/local/etc/php/php.ini
RUN sed -i -e 's/;extension=pdo_pgsql/extension=pdo_pgsql/' /usr/local/etc/php/php.ini

Answer 1

You are configuring docker under the default network mode: bridge. In order for the php-fpm-service to be able to access the postgres-service you need to make the following modifications:
In the docker-compose.yml file you'll need to add depends_on to php-fpm-service
# php
php-fpm-service:
build:
context: .
dockerfile: ./php-fpm/Dockerfile
container_name: php-fpm-container
ports:
- "9000:9000"
working_dir: /var/www/project
volumes:
- ./app:/var/www/project
networks:
- my_test_app
depends_on:
- postgres-service
In your PHP config, you need modify localhost to postgres-service and using port 5432:
$dsn = 'pgsql:host=postgres-service;port=5432;dbname=db_my_test_app';