Understanding the ECONNREFUSED Error
The ECONNREFUSED error typically indicates that a connection attempt has failed because the target machine actively refused it. This can happen when using Sequelize with Node.js in a Dockerized environment if Sequelize attempts to connect to the database before it’s ready or if there are network issues preventing a successful connection.
Checking Container Dependencies
One common fix is to ensure that your Node.js application waits for the database container to be fully up and running before it tries to establish a connection. Docker Compose can be used to manage container dependencies with the depends_on attribute.
Configuring Network Settings
Another solution is to check your Docker network settings. Ensure that your Node.js app is on the same network as your database service and that the service names are correctly used as hostnames in your Sequelize configuration.
Sample Docker-Compose Configuration
Below is an example of a docker-compose.yml file designed to ensure proper order of service startup and network configuration:
version: '3'
services:
db:
image: postgres
networks:
- back-tier
app:
build: .
command: npm start
depends_on:
- db
networks:
- back-tier
networks:
back-tier:
driver: bridge
With this configuration, the app service will wait for the db service to be available before starting. Additionally, both services are part of the same network, ensuring they can communicate with each other.
Adjusting Sequelize Configuration
In your Sequelize configuration, you would use the service name as the host. Here’s a code snippet for the Sequelize config:
const sequelize = new Sequelize('database', 'username', 'password', {
host: 'db',
dialect: 'postgres',
//... other config
});
Note that ‘db’ is the service name defined for the database in the docker-compose.yml file. Adjusting this configuration can often resolve the ECONNREFUSED error.
