Example docker network beginner

docker.sh

docker rm -f $(docker ps -a)
docker network delete postgres-network
docker network create postgres-network
docker rm -f postgres-container
docker run --name postgres-container \
    --network postgres-network \
    -e POSTGRES_PASSWORD=mysecretpassword \
    -e POSTGRES_USER=test \
    -p 5432:5432 \
    -d postgres
docker build -t myapp-image .
docker rm -f myapp-container
docker run --name myapp-container \
    --network postgres-network myapp-image

Dockerfile

# Use an official Node.js runtime as a parent image
FROM node:14

# Set the working directory in the container
WORKDIR /usr/src/app

# Copy package.json and package-lock.json to the working directory
COPY package*.json ./

# Install app dependencies
RUN npm install

# Bundle app source
COPY . .

# Expose the port the app runs on
EXPOSE 3000

# Define environment variable
ENV NODE_ENV=production

# Command to run the application
CMD ["npm", "start"]

index.js

const { Sequelize } = require('sequelize')

// Initialize Sequelize with your PostgreSQL credentials
const sequelize = new Sequelize(
  'postgres://test:mysecretpassword@postgres-container:5432/database',
  {
    dialect: 'postgres',
  }
)

// Test the connection
async function testConnection() {
  await sequelize.authenticate()
  console.log('Connection has been established successfully.')
}

// Call the testConnection function
testConnection()

package.json

{
  "name": "test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "node index.js"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "pg": "^8.11.3",
    "sequelize": "^6.35.2"
  }
}