Connect to database from another container - docker

Question

Please help me if it's possible.
I need to start 2 applications with a single database.
I have 2 applications. First domain.com, 2-nd api.domain.com. Each application has docker-compose.yaml files.
domain.com - CMS
version: "3.8"
services:
web:
container_name: domain_web
build:
context: ./docker/php
dockerfile: Dockerfile
working_dir: /var/www/html
#command: composer install
volumes:
- ./:/var/www/html
- ./docker/php/app.conf:/etc/apache2/sites-available/000-default.conf
- ./docker/php/hosts:/etc/hosts
networks:
domain:
ipv4_address: 10.9.0.5
networks:
domain:
driver: bridge
ipam:
config:
- subnet: 10.9.0.0/16
gateway: 10.9.
volumes:
bel_baza:
api.domain.com - Laravel 5.6
version: "3.8"
services:
web:
container_name: api_domain_web
build:
context: ./docker/php
dockerfile: Dockerfile
working_dir: /var/www/html
# command: composer install
volumes:
- ./:/var/www/html
- ./docker/php/app.conf:/etc/apache2/sites-available/000-default.conf
- ./docker/php/hosts:/etc/hosts
networks:
api_domain:
ipv4_address: 10.15.0.5
db:
image: mysql:5.7
command: --default-authentication-plugin=mysql_native_password
restart: always
container_name: api_domain_db
environment:
MYSQL_ROOT_PASSWORD: root
MYSQL_DATABASE: domain
MYSQL_USER: user
MYSQL_PASSWORD: user
volumes:
- api_domain_baza:/var/lib/mysql
- ./docker/db:/docker-entrypoint-initdb.d
networks:
api_domain:
ipv4_address: 10.15.0.6
phpmyadmin:
image: phpmyadmin
restart: always
container_name: api_domain_pma
networks:
api_domain:
ipv4_address: 10.15.0.7
redis:
image: redis:3.0
container_name: api_domain_redis
networks:
api_domain:
ipv4_address: 10.15.0.10
networks:
api_domain:
driver: bridge
ipam:
config:
- subnet: 10.15.0.0/16
gateway: 10.15.0.1
volumes:
api_domain_baza:
api_domain started successfully.
I need to connect domain.com with database api_domain_db. For connecting host, I used IP address 10.15.0.6. First application not connected to the database from 2nd application.
What is my problem?
How I can connect domain.com with the database of 2nd application?

Answer 1

your problem is your are using separate docker compose applications for each application. And by default those applications can not access each other inner parts:
By default Compose sets up a single network for your app. Each container for a service joins the default network and is both reachable by other containers on that network, and discoverable by them at a hostname identical to the container name.
doc is here - https://docs.docker.com/compose/networking/
So it is like it creates separate network for each docker compose.
if you want them both to see each other inner part you can create external docker network as this:
docker network create --subnet 10.1.0.0/24 network_name
and then use that network in both docker compose like this:
networks:
default:
external:
name: network_name
services:
.....
if you need fixed IPs, you can define them as
app:
image: ...
networks:
default:
ipv4_address: 10.1.0.10