This example shows how to build REST API using Node.js, Express.js and MySQL database and then run the application inside Container.

1. Create folder named docker_restapi
2. Create a folder named backend inside docker_restapi
3. Then create the express application inside folder backend ( https://peatutor.com/express/Examples/mysql_index.php)
4. Add a file named .env inside docker_restapi with below code

   MYSQLDB_USER=root
   MYSQLDB_ROOT_PASSWORD=root
   MYSQLDB_LOCAL_PORT=3307
   MYSQLDB_DOCKER_PORT=3306
   
   NODE_LOCAL_PORT=6868
   NODE_DOCKER_PORT=3000
   

5. Add a file named docker-compose.yml inside docker_restapi with below code

   version: '3.8'
   
   services:
     mysqldb:
       image: mysql:latest
       restart: unless-stopped
       env_file: ./.env
       environment:
         - MYSQL_ROOT_PASSWORD=$MYSQLDB_ROOT_PASSWORD
       ports:
         - $MYSQLDB_LOCAL_PORT:$MYSQLDB_DOCKER_PORT
       volumes:
         - db:/var/lib/mysql
         - ./my_dump.sql:/docker-entrypoint-initdb.d/my_dump.sql
         - ./user_create.sql:/docker-entrypoint-initdb.d/user_create.sql
   
     app:
       depends_on:
         - mysqldb
       build: 
         context: ./backend
         dockerfile: Dockerfile
       restart: always
       env_file: ./.env
       ports:
         - $NODE_LOCAL_PORT:$NODE_DOCKER_PORT
       environment:
         - DB_HOST=mysqldb
         - DB_USER=$MYSQLDB_USER
         - DB_PASSWORD=$MYSQLDB_ROOT_PASSWORD
         - DB_PORT=$MYSQLDB_DOCKER_PORT
       volumes:
         - ./backend:/backend
       stdin_open: true
       tty: true
   
   volumes:
     db:
   
   

   Note:
   In this example I had files:
   • my_dump.sql, which will create database named netdb and the tables
   • user_create.sql which includes rows

     CREATE USER 'myadmin'@'%' IDENTIFIED BY 'adminpass';
     GRANT ALL ON *.* TO 'myadmin'@'%';
     
     CREATE USER 'netuser'@'localhost' IDENTIFIED BY 'netpass';
     GRANT ALL ON netdb.* TO 'netuser'@'localhost';
     

   And those files will be executed when the server starts, because I have copied them to folder /docker-entrypoint-initdb.d
   And the database connection string is like this

   "mysql://netsuser:netpass@mysqldb/netdb"
   

   And when I connect from my host to the database, I will use port 3307 and user myadmin. I am using port 3307, so that I can also run MySQL in my host, even if the Docker-MySQL is running.
6. Add a file named .dockerignore inside backend with below code

   backend/node_modules/
   

7. Add a file named Dockerfile inside backend with below code

   FROM node:19
   
   WORKDIR /backend
   COPY package.json .
   RUN npm install
   COPY . .
   CMD npm start
   

8. Inside folder docker_restapi execute command docker-compose up -d
9. Now you should be able to reach the application from url
   • http://localhost:6868 in your host computer
   • http://localhost:3000 in Docker container

FROM node:19

WORKDIR /backend
COPY package.json .
RUN npm install -g nodemon
RUN npm install
COPY . .
CMD npm start

"scripts": {
    "start": "nodemon --legacy-watch ./bin/www",
    "docker": "docker-compose up --build"
  },