docker nodejs container cant connect mysql container - mysql

Question

I'm running Docker server in Digital Ocean. There I have two containers Nodejs and Mysql. Mysql container has open port to 3306.
When trying to access mysql via nodejs by Docker Server ip + port. I get Error: connect ETIMEDOUT.
When I run same nodejs docker setup in my local computer it works fine. Is there something i'm missing?
Here is nodejs docker-composer.yml:
version: '2'
services:
test-web-install:
image: example-nodejs:latest
working_dir: /home/app
volumes:
- ./:/home/app
command: sh -c 'nodemon'
environment:
- NODE_ENV=development
- DB_HOST=192.168.11.207 #or public ip in internet
- DB_PORT=3036
- DB_PASSWORD=root
- DB_USER=root
- DB_DATABASE=root
ports:
- "3000:3000"
Here is docker-composer.yml for mysql
mysql:
container_name: flask_mysql
restart: always
image: mysql:5.6
environment:
MYSQL_ROOT_PASSWORD: 'root' # TODO: Change this
MYSQL_USER: 'root'
MYSQL_PASS: 'root'
MYSQL_DATABASE: 'root'
volumes:
- ./data:/var/lib/mysql
ports:
- "3036:3306"
restart: always

Answer 1

I'll modify answer as we advance - Following your comments, while I can not access to your env, lets try to solve this incrementally:
Let's make the db visible to the node.js server
See how it works and then probably dive into env networking configuration.
There 2 ways to solve 1st and may be 2nd problem as i see without being able to touch your env:
1st one will ensure that the server sees the database, but if you can not connect to the db from outside seems there firewall/droplet networking configuration issue, and you can try 2nd way (wont likely to change, but it's good to try). This assumes you use same docker compose and same bridge cusom network:
version: '2'
services:
test-web-install:
image: example-nodejs:latest
working_dir: /home/app
volumes:
- ./:/home/app
command: sh -c 'nodemon'
environment:
- NODE_ENV=development
- DB_HOST= mysql
- DB_PORT=3036
- DB_PASSWORD=root
- DB_USER=root
- DB_DATABASE=root
ports:
- "3000:3000"
networks:
inner:
alias: server
mysql:
container_name: flask_mysql
restart: always
image: mysql:5.6
environment:
MYSQL_ROOT_PASSWORD: 'root' # TODO: Change this
MYSQL_USER: 'root'
MYSQL_PASS: 'root'
MYSQL_DATABASE: 'root'
volumes:
- ./data:/var/lib/mysql
ports:
- "<externalEnvIp>:3036:3306"
restart: always
networks:
inner:
alias: mysql
networks:
inner:
driver: bridge
driver_opts:
com.docker.network.enable_ipv6: "true"
com.docker.network.bridge.enable_ip_masquerade: "true"
ipam:
driver: default
config:
- subnet: 172.16.100.0/24
gateway: 172.16.100.1
Option 2 :
version: '2'
services:
test-web-install:
image: example-nodejs:latest
working_dir: /home/app
volumes:
- ./:/home/app
command: sh -c 'nodemon'
environment:
- NODE_ENV=development
- DB_HOST= mysql
- DB_PORT=3036
- DB_PASSWORD=root
- DB_USER=root
- DB_DATABASE=root
ports:
- "3000:3000"
network_mode: "host"
mysql:
container_name: flask_mysql
restart: always
image: mysql:5.6
environment:
MYSQL_ROOT_PASSWORD: 'root' # TODO: Change this
MYSQL_USER: 'root'
MYSQL_PASS: 'root'
MYSQL_DATABASE: 'root'
volumes:
- ./data:/var/lib/mysql
ports:
- "3036:3306"
restart: always
network_mode: "host"
More precise solution (to find the roots of the problem) would involve into deep digging into your env network configuration, docker networking settings etc., but those solutions may help and fix your problem for now.
Pleasse after you try please output the results.

Answer 2

The docker networking doesn't allow you to go from inside a container back out to the host IP to connect to a port exposed by another container. I haven't dug into this enough to see if that's due to the iptables rules or perhaps something inside of docker-proxy. Either way, it's never been worth investigating since container-to-container networking is a built in feature of docker.
To use docker's networking, the containers need to be on the same docker network, and you reference them by their container name in DNS. With docker-compose, normally you can use the service name in place of the container name (e.g. test-web-install and mysql from your examples) since compose creates an alias for these. However, since you've overridden the container name for mysql, use your flask_mysql container name instead.
In your scenario, since you've split up the startup with two separate docker-compose.yml files, you'll be on separate networks created by compose. You have two options to resolve this:
Merge the two into a single docker-compose.yml (BlackStork gave an example of this).
Use an externally defined network that you create in advance.
To do the latter, first create your network:
docker network create dbnet
Then update your docker-compose.yml for the app to look like:
version: '2'
networks:
dbnet:
external: true
services:
test-web-install:
image: example-nodejs:latest
working_dir: /home/app
volumes:
- ./:/home/app
command: sh -c 'nodemon'
environment:
- NODE_ENV=development
- DB_HOST=flask_mysql
- DB_PORT=3036
- DB_PASSWORD=root
- DB_USER=root
- DB_DATABASE=root
ports:
- "3000:3000"
networks:
- dbnet
And the docker-compose.yml for mysql:
version: '2'
networks:
dbnet:
external: true
services:
mysql:
container_name: flask_mysql
restart: always
image: mysql:5.6
environment:
MYSQL_ROOT_PASSWORD: 'root' # TODO: Change this
MYSQL_USER: 'root'
MYSQL_PASS: 'root'
MYSQL_DATABASE: 'root'
volumes:
- ./data:/var/lib/mysql
ports:
- "3036:3306"
restart: always
networks:
- dbnet