Trying to connect all my docker containers to a separate MariaDB container - docker

Question

So, I've setup several container apps that use MariaDB as their db backend, using docker-compose.
Containers are setup as needed and therefore MariaDB gets installed each time on every container that uses the db.
For example, I have some containers (PHPMyAdmin, NGiNX-PM, etc.) that use MariaDB, and they, in turn, have a version of it installed within their container. I also have a separate container (MariaDB) that I would rather have shared amongst the other containered apps and, thereby, I'd only have to maintain one version of the db.
I've searched for a solution, but no luck. Needless to say, I'm a noob at docker.
The only thing I can come up with is that all the apps need to be installed through the same docker-compose.yaml file to use the same db? That would make for a very long file if I had many containers running, and I'd prefer to have a directory per app and all the app's contents available in this one location.
I'm sure there is a way, I just haven't been able to figure it out.
So this is what I've tried:
The following setup is what I've tried but I am unable to get it to work:
(/docker/apps/mariadb/mariadb.yml)
version: '3.9'
networks:
NET:
external: true
services:
#############################################################################################
# MariaDB (docker-compose -f mariadb.yml up -d) #
#############################################################################################
mariadb:
image: jsurf/rpi-mariadb:latest
restart: unless-stopped
environment:
- TZ=${TIMEZONE}
- MYSQL_DATABASE=dockerApps
- MYSQL_USER=root
- MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD}
- MYSQL_PASSWORD=${MYSQL_PASSWORD}
volumes:
- $HOME/docker/apps/mariadb/db:/var/lib/mysql
expose:
- '3306'
networks:
- NET
(/docker/apps/nginxpm/nginxpm.yml)
version: '3.9'
networks:
NET:
external: true
services:
#############################################################################################
# NGiNX Proxy Manager (docker-compose -f nginxpm.yml up -d) #
#############################################################################################
nginxpm:
container_name: NGiNX_Proxy_Manager
image: 'jc21/nginx-proxy-manager:latest'
ports:
- '80:80'
- '81:81'
- '443:443'
volumes:
- ./config.json:/app/config/production.json
- ./data:/data
- ./letsencrypt:/etc/letsencrypt
networks:
- NET
depends_on:
- mariadb
(/docker/apps/phpmyadmin/phpmyadmin.yml)
version: "3.9"
networks:
NET:
external: true
services:
#############################################################################################
# phpMyAdmin (docker-compose up -d -OR- docker-compose -f phpmyadmin.yml up -d) #
#############################################################################################
phpmyadmin:
image: phpmyadmin:latest
container_name: phpMyAdmin
restart: unless-stopped
environment:
PMA_HOST: mariadb
PMA_USER: root
PMA_PASSWORD: ${MYSQL_PASSWORD}
volumes:
# Must add ServerName directive to end of file "ServerName 127.0.0.1"
- $HOME/docker/apps/phpmyadmin/apache2.conf:/etc/apache2/apache2.conf
ports:
- '8004:80'
networks:
- NET
Any help in this matter is greatly appreciated.

Answer 1

Ok, so after some more reading and testing, I've found the answer to my issue. I was assuming that "depends_on" was supposed to connect the containers, somehow. Not true!
I found that "external_links" is the correct way of connecting them.
So, my final docker-compose file looks like this:
(/docker/apps/nginxpm/nginxpm.yml)
version: '3.9'
networks:
NET:
external: true
services:
#############################################################################################
# NGiNX Proxy Manager (docker-compose -f nginxpm.yml up -d) #
#############################################################################################
nginxpm:
container_name: NGiNX_Proxy_Manager
image: 'jc21/nginx-proxy-manager:latest'
ports:
- '80:80'
- '81:81'
- '443:443'
volumes:
- ./config.json:/app/config/production.json
- ./data:/data
- ./letsencrypt:/etc/letsencrypt
networks:
- NET
external_links:
- mariadb