Multi Docker-Compose projects sharing service - docker

Question

I am attempting to create multiple Docker-Compose projects and have them share a single service, a database server. I'm currently unable to get projects to use my mariadb instance. I'm not sure if my issues is in traefik or docker. I can get wordpress to recognize the database if it is included in the same docker-compose, but as I would ultimately like to not have multiple instances of a database server running, I would prefer it to be it's own project.
# ~/docker/traefik/docker-compose.yml
version: "3.3"
services:
traefik:
image: "traefik:v2.2"
container_name: "traefik"
command:
- "--api=true"
- "--providers.docker=true"
- "--providers.docker.exposedbydefault=false"
- "--entrypoints.web.address=:80"
- "--entrypoints.websecure.address=:443"
- "--certificatesresolvers.myresolver.acme.dnschallenge=true"
- "--certificatesresolvers.myresolver.acme.dnschallenge.provider=namedotcom"
- "--certificatesresolvers.myresolver.acme.caserver=https://acme-staging-v02.api.letsencrypt.org/directory"
- "--certificatesresolvers.myresolver.acme.email=<MY-EMAIL>"
- "--certificatesresolvers.myresolver.acme.storage=/letsencrypt/acme.json"
networks:
t2_proxy:
ports:
- "80:80"
- "443:443"
environment:
- "NAMECOM_USERNAME=<My-USERNAME>
- "NAMECOM_API_TOKEN=<My-Token>
labels:
# Dashboard
- "traefik.enable=true"
- "traefik.http.routers.traefik.rule=Host(`api.mydomain.com`)"
- "traefik.http.routers.traefik.service=api#internal"
- "traefik.http.routers.traefik.middlewares=admin"
- "traefik.http.routers.traefik.tls.certresolver=myresolver"
- "traefik.http.routers.traefik.entrypoints=websecure"
- "traefik.http.middlewares.admin.basicauth.users=myuser:mypasswordhash/"
# middleware redirect
- "traefik.http.middlewares.redirect-to-https.redirectscheme.scheme=https"
# global redirect to https
- "traefik.http.routers.redirs.rule=hostregexp(`{host:.+}`)"
- "traefik.http.routers.redirs.entrypoints=web"
- "traefik.http.routers.redirs.middlewares=redirect-to-https"
volumes:
- "./letsencrypt:/letsencrypt"
- "/var/run/docker.sock:/var/run/docker.sock:ro"
networks:
t2_proxy:
# ~/docker/db/docker-compose.yml
version: '3.3'
services:
mysql:
image: mariadb
container_name: "mariadb"
restart: always
environment:
MYSQL_ROOT_PASSWORD: example
MYSQL_DATABASE: wordpressDB
MYSQL_USER: wordpressUSER
MYSQL_PASSWORD: wordpressPW
networks:
default:
ports:
- 3306:3306
adminer:
image: adminer
restart: always
container_name: "adminer"
labels:
- "traefik.enable=true"
- "traefik.http.routers.adminer.rule=PathPrefix(`/adminer`)"
- "traefik.http.routers.adminer.entrypoints=websecure"
- "traefik.http.routers.adminer.tls.certresolver=myresolver"
networks:
- default
- traefik_t2_proxy
networks:
default:
traefik_t2_proxy:
external: true
# ~/docker/wordpress/docker-compose.yml
version: '3.3'
services:
wordpress:
image: wordpress:latest
restart: always
container_name: "mySite"
environment:
WORDPRESS_DB_HOST: db:3306
WORDPRESS_DB_USER: wordpressUSER
WORDPRESS_DB_PASSWORD: wordpressPW
WORDPRESS_DB_NAME: wordpressDB
networks:
traefik_t2_proxy:
db_default:
labels:
- "traefik.enable=true"
- "traefik.http.routers.wp2.rule=PathPrefix(`/wordpress`)"
- "traefik.http.routers.wp2.entrypoints=websecure"
- "traefik.http.routers.wp2.tls.certresolver=myresolver"
volumes:
db_data: {}
networks:
traefik_t2_proxy:
external: true
db_default:
external: true

Answer 1

You can have multiple docker-compose files, with the same network and run them together as below:
docker-compose -f docker-compose-1.yml -f docker-compose-2.yml up -d
But if you need the services to recognize eachother, the networks should be the same. Give your traefik_t2_proxy network to mysql too.