Lately, as a move towards efficient continuous integration and continuous development( CI/CD ), I have been dockerizing all my applications and running these applications inside containers using Docker. NodeJS turned out to be a hard nut to crack...but alas it's finally cracked. This is how i managed to dockerize and run a NodeJS RESTFUL app at long last.

1. Navigate to your preferred file system and create a directory and then change into the created directory.
   $ mkdir <foldername> && cd <foldername>

2. Create a new nodejs app using npm or yarn by running:
   $ npm init <application name>

3. Add your app dependencies such as Express:
   $ npm install express --save

4. You should now have a package.json file, the node_modules folders and maybe some lock files. Create the main file this command under your app directory terminal window / shell by running: $ touch <filename>.js
   5.Edit the package.json file. Add this if not existent under the scripts defintion and save the file.
   

"scripts": {
"start": "node <mainfile>"
}

1. To dockerize the app; add the following files from the terminal under the app directory file system. $ touch Dockerfile $ touch docker-compose.yml
2. Open and Edit the Dockerfile with the following contents.

# obtain the node image
FROM node
# change to the working directory
WORKDIR <directory_name>
#move the package file to the current working directory
COPY package*.json ./
# install the depedencies
RUN npm install
COPY . .
# run the app
CMD [ "node", <mainfile> ]

1. Make a new directory inside the app folder to handle the nginx configuration, cd into the folder and create a new nginx conf file. mkdir nginx && cd nginx && touch default.conf
2. Edit the default conf file with these contents; environment name and port should be obtained and defined in the docker-compose.yml file.

http {
 upstream backend {
   server <environment_name: port>
 }
 server {
  location / {
    proxy_pass http://backend;
  } 
 }
}

1. Edit the docker-compose.yml with these contents.

versions: '3',
services:
  nginx_server:
    image: nginx #image of the nginx
    volumes: 
     - './nginx/default.conf:/etc/nginx/nginx.conf'
    ports:
     - '8000:80'
  #define the node app container
  app:
   container_name: <container name>
   build:
    context: .
    dockerfile: Dockerfile #name of the dockerfile we created
  ports:
   - '3000:80' #docker container port = 3000, host port= 80
  environment:
   - APPID=3000