Docker - SequelizeConnectionRefusedError: connect ECONNREFUSED 127.0.0.1:3306 - node.js

Question

I'm trying to get my nodejs application up and running using a docker container. I have no clue what might be wrong. The credentials seems to be passed correctly when I debug the credentials with the console. Also firing up sequel pro and connecting directly with the same username and password seems to work. When node starts in the container I get the error message:
SequelizeConnectionRefusedError: connect ECONNREFUSED 127.0.0.1:3306
The application itself is loading correctly on port 3000, however no data is retrieved from the database. If have also tried adding the environment variables directly to the docker compose file, but this also doesn't seem to work.
My project code is hosted over here: https://github.com/pietheinstrengholt/rssmonster
The following database.js configuration is used. When I add console.log(config) the correct credentials from the .env file are displayed.
require('dotenv').load();
const Sequelize = require('sequelize');
const fs = require('fs');
const path = require('path');
const env = process.env.NODE_ENV || 'development';
const config = require(path.join(__dirname + '/../config/config.js'))[env];
if (config.use_env_variable) {
var sequelize = new Sequelize(process.env[config.use_env_variable], config);
} else {
var sequelize = new Sequelize(config.database, config.username, config.password, config);
}
module.exports = sequelize;
When I do a console.log(config) inside the database.js I get the following output:
{
username: 'rssmonster',
password: 'password',
database: 'rssmonster',
host: 'localhost',
dialect: 'mysql'
}
Following .env:
DB_HOSTNAME=localhost
DB_PORT=3306
DB_DATABASE=rssmonster
DB_USERNAME=rssmonster
DB_PASSWORD=password
And the following docker-compose.yml:
version: '2.3'
services:
app:
depends_on:
mysql:
condition: service_healthy
build:
context: ./
dockerfile: app.dockerfile
image: rssmonster/app
ports:
- 3000:3000
environment:
NODE_ENV: development
PORT: 3000
DB_USERNAME: rssmonster
DB_PASSWORD: password
DB_DATABASE: rssmonster
DB_HOSTNAME: localhost
working_dir: /usr/local/rssmonster/server
env_file:
- ./server/.env
links:
- mysql:mysql
mysql:
container_name: mysqldb
image: mysql:5.7
command: --default-authentication-plugin=mysql_native_password
environment:
MYSQL_RANDOM_ROOT_PASSWORD: "yes"
MYSQL_DATABASE: "rssmonster"
MYSQL_USER: "rssmonster"
MYSQL_PASSWORD: "password"
ports:
- "3307:3306"
volumes:
- /var/lib/mysql
restart: unless-stopped
healthcheck:
test: ["CMD", "mysqladmin" ,"ping", "-h", "localhost"]
timeout: 5s
retries: 10
volumes:
dbdata:
Error output:
{ SequelizeConnectionRefusedError: connect ECONNREFUSED 127.0.0.1:3306
app_1 | at Promise.tap.then.catch.err (/usr/local/rssmonster/server/node_modules/sequelize/lib/dialects/mysql/connection-manager.js:128:19)
app_1 | From previous event:
app_1 | at ConnectionManager.connect (/usr/local/rssmonster/server/node_modules/sequelize/lib/dialects/mysql/connection-manager.js:125:13)
app_1 | at sequelize.runHooks.then (/usr/local/rssmonster/server/node_modules/sequelize/lib/dialects/abstract/connection-manager.js:306:50)
app_1 | From previous event:
app_1 | at ConnectionManager._connect (/usr/local/rssmonster/server/node_modules/sequelize/lib/dialects/abstract/connection-manager.js:306:8)
app_1 | at ConnectionManager.getConnection (/usr/local/rssmonster/server/node_modules/sequelize/lib/dialects/abstract/connection-manager.js:247:46)
app_1 | at Promise.try (/usr/local/rssmonster/server/node_modules/sequelize/lib/sequelize.js:564:34)
app_1 | From previous event:
app_1 | at Promise.resolve.retryParameters (/usr/local/rssmonster/server/node_modules/sequelize/lib/sequelize.js:464:64)
app_1 | at /usr/local/rssmonster/server/node_modules/retry-as-promised/index.js:60:21
app_1 | at new Promise (<anonymous>)

Answer 1

Insteaf of localhost point to mysql which is the service name (DNS) that nodejs will resolve into the MySQL container:
DB_HOSTNAME: mysql
And
{
...
host: 'mysql',
...
}

Answer 2

Inside of the container you should reference the container by the name you gave in your docker-compose.yml file.
In this case you should use
DB_HOSTNAME: mysql

Answer 3

After searching and digging up through several googling attempt, the culprit of the problem soon appear. In this context, the database server is not in the same machine. In other words, the MySQL Database Server address is not localhost. So, how can the above MySQL database configuration by default is pointing to localhost address. Well, it seems that if there is no further definition of the host address, it will connect to the localhost address by default. Read the article for further reference about sequelize syntax pattern in this link.
So, in order to solve the problem, just modify the file with the right configuration database. The following is the correction of the configuration database :
const sequelize = require("sequelize")
const db = new sequelize("db_master","db_user","password", {
host : "10.0.2.2",
dialect: "mysql"
});
db.sync({});
module.exports = db;
Actually, the NodeJS application is running in a virtual server. It is a guest machine run in a VirtualBox application. On the other hand, MySQL Database server exist outside the guest machine. It is available in the host machine where the VirtualBox application is running. The host machine IP address is 10.0.2.2. So, in order to connect to MySQL Database Server in the host machine, the IP address of the host is 10.0.2.2.

Answer 4

use your connection string as :
mysql://username:password#mysql:(port_running_on_container)or(exposed_port)/db_name

Answer 5

Answers already exist, but to provide some further explanation:
You can't use 127.0.0.1 (localhost) to access other services/containers since each container will view that as inside itself. When running docker-compose, all your services will be entered into the same docker network. All services inside the same docker network, are able to reach eachother by service name.
hence, as already stated in previous answers: in your configuration, change db hostname from localhost to mysql.

Answer 6

three things to check before
make sure your service name must be MySQL
in Configure DB_HOST also a MySQL
And your backend service depends on mysql in docker-compose.yml
here is my success code
export const db = new Sequelize(
process.env.DB_NAME,
process.env.DB_USER,
process.env.DB_PASSWORD,
{
port: process.env.DB_PORT,
host:'mysql',
dialect: "mysql",
logging: false,
pool: {
max: 5,
min: 0,
acquire: 30000,
idle: 10000
},
}
);