mysql host not resolving with docker container for Nodejs and express - mysql

Question

I'm trying to use NodeJS+Express, MySQL, phpmyadmin altogether. phpmyadmin itself resolving the address by port 8183 in my situation. But whenever I'm going to connect it through with mysql js package of NodeJS. it is not working and throwing error
Error: connect ECONNREFUSED 127.0.0.1:3306
Note: I tried with few variations as host anyone didn't work for me!
example: mysql, my_machine_ip, localhost, 0.0.0.0
nothing worked for me.
Here's my yml file.
version : '3'
services:
phpmyadmin:
image: phpmyadmin/phpmyadmin
container_name: node_pa
links:
- mysql
depends_on:
- mysql
environment:
PMA_HOST: mysql
PMA_PORT: 3306
PMA_ARBITRARY: 1
restart: always
ports:
- 8183:80
node_backend:
container_name: node_with_pa_msql
build: ./backend_app
# volumes:
# - ./backend_app:/usr/src/app
links:
- mysql
depends_on:
- mysql
restart: on-failure
ports:
- 3004:4006
mysql:
image: mysql:latest
container_name: node_mysql
# volumes:
# - backend_app/db_sample:/docker-entrypoint-initdb.d
environment:
MYSQL_USER: user
MYSQL_PASSWORD: user
MYSQL_ROOT_PASSWORD: root
MYSQL_DATABASE: default_schema
And mysqlJS connection details
// environment variables
const PORT = process.env.PORT || 4006;
const HOST = process.env.HOST || 'localhost';
// // mysql credentials
const connection = mysql.createConnection({
host: HOST,
user: process.env.MYSQL_USER || 'root',
password: process.env.MYSQL_PASSWORD || 'root',
connectTimeout: 20000
});
So, phpmyadmin is working and i can access databases/create/delete/edit by that so this assure that mysql itself also working, But right now I'm unable to connect it with mysqlJS of my nodejs app.
here's the sample project with the problem if you would like to try on your machine project GitHub link with YAML file
Note: Check answer added a complete solution of this issue.

Answer 1

I'm assuming the phpMyAdmin instance is working since you are actually passing the env var PMA_HOST and PMA_PORT correctly to the container.
You will need to do the same for the JS application, so your docker-compose config will look like the following:
node_backend:
container_name: node_with_pa_msql
build: ./backend_app
# volumes:
# - ./backend_app:/usr/src/app
environment:
MYSQL_HOST: mysql
MYSQL_PORT: 3306
links:
- mysql
depends_on:
- mysql
restart: on-failure
ports:
- 3004:4006
Then in your JS code you need to get the connection information from your env variables:
// environment variables
const PORT = process.env.MYSQL_PORT || 4006;
const HOST = process.env.MYSQL_HOST || 'localhost';
// // mysql credentials
const connection = mysql.createConnection({
host: HOST,
port: PORT,
user: process.env.MYSQL_USER || 'root',
password: process.env.MYSQL_PASSWORD || 'root',
connectTimeout: 20000
});
This works because when you link the mysql container, a hosts entry is added to your js container which makes the hostname mysql point to the (docker internal) ip address of the mysql container.

Answer 2

Finally after a big mess, solved this issue!
With stated above YAML file. everything is almost OK, But the main problem is order of image.
That means I have total 3 image from them node is dependent to mysql. So first mysql must has to start so then you can get the connection of mysql and use it with your application (nodeJS). This is the reason why any host were not resolving with my implementation.
I followd this article: https://docs.docker.com/compose/startup-order/
and for implementation example this: https://dev.to/hugodias/wait-for-mongodb-to-start-on-docker-3h8b
You are done! now use your desired driver
Now
this is node (mysqlJS) package specific. the package by itself doesn't support latest mysql and if you use latest tagged mysql mysql:latest then you may face this issue.
Error: ER_NOT_SUPPORTED_AUTH_MODE: Client does not support authentication protocol requested by server; consider upgrading MySQL client docker mysql node
quick solution downgrade it to lower until it works. I'm not sure about minimum version but mysql:5.6 works!
If you want a quick starter with everything phpmyadmin,mysql,nodejs app
then you can use this repo: Here