Docker error connecting to host mysql - docker

Question

Docker version 17.03.1-ce, build c6d412e
OS: Ubuntu
I am trying to connect to host mysql from the docker container. but i am getting this error.
Error: connect ECONNREFUSED 0.0.0.0:3306
I am getting same for mysql if i use mysql container. Tried 127.0.0.1 and localhost also.
version: '2'
services:
### Applications Code Container
#############################
applications:
image: tianon/true
volumes:
- ${APPLICATION}:/var/www/html
apache2:
build:
context: ./apache2
volumes_from:
- applications
volumes:
- ${APACHE_HOST_LOG_PATH}:/var/log/apache2
- ./apache2/sites:/etc/apache2/sites-available
ports:
- "${APACHE_HOST_HTTP_PORT}:80"
- "${APACHE_HOST_HTTPS_PORT}:443"
networks:
- frontend
- backend
node:
build:
context: ./node
volumes_from:
- applications
ports:
- "4000:30001"
networks:
- frontend
- backend
### MySQL Container #########################################
mysql:
build:
context: ./mysql
environment:
- MYSQL_DATABASE=${MYSQL_DATABASE}
- MYSQL_USER=${MYSQL_USER}
- MYSQL_PASSWORD=${MYSQL_PASSWORD}
- MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD}
volumes_from:
- applications
volumes:
- ${DATA_SAVE_PATH}/mysql:/var/lib/mysql
- ./mysql/docker-entrypoint-initdb.d:/docker-entrypoint-initdb.d
ports:
- "${MYSQL_PORT}:3306"
networks:
- backend
### Networks Setup ############################################
networks:
frontend:
driver: "bridge"
backend:
driver: "bridge"
### Volumes Setup #############################################
volumes:
mysql:
driver: "local"
mongo:
driver: "local"
node:
driver: "local"
apache2:
driver: "local"

Answer 1

Instead of using 0.0.0.0, 127.0.0.1 or localhost, you should use your host machine's IP. This is because each container is a individual node in the network.
Or if you can inspect your MySQL container, and get the IP of it, you can use the IP as well, since they are on the same network.