Creating a Docker container for a NodeJs application: Express + Mongo + Docker Compose


This is a Docker tutorial for creating a NodeJs container using expressjs and mongoose, above is the vid and below you will find the steps followed.

Steps

  • Pre-reqs
    • Have node.js installed
    • And docker installed (make sure you have docker-compose as well)
  • Create an simple node app using expressjs and mongoose
  • Modify your container and create a docker-compose file
  • Build and Run your new container

Create your simple node app

  • Initialize the node app
    • npm init
  • Install the dependencies for our app
    • npm install --save express mongoose 
  • Create the database.js
  • Create the index.js

Create a dockerfile

  • Include container with node preinstalled: 
    • FROM node
  • Create default/working directory: 
    • WORKDIR /usr/src/app
  • Copy package.json to workdir and install dependencies (which we will need in this case😊):  
    • COPY package.json .
    • RUN npm install
  • Copy the rest of the app (just the index.js file in this case)
    • COPY . .
  • Expose the port required for reaching our expressjs app
    • EXPOSE 3000
  • Add a command to run when this container is started
    • CMD ["node", "index.js"]

Create a docker-compose.yml file

  • Version for the docker-compose file:
    • version: '3'
  • The list of services and their respective configurations: 
    • services:
  • Our app service: web
    • The name of each service, they can also work as a way to identify each service and connect to them within a container (for example you could connect to the mongo database using the name of the service: mongodb://mongo/test):
      • web
    • The name of the image that we want to build
      • image: docker-node-express-mongoapp
    • The folder in which the dockerfile is located (if you have everything in the same folder then just adding "build: ./" would suffice)
      • build: ./web-site
    • the command to run when the container is up (this will override any CMD command on the dockerfile for that container)
      • command: node index.js
    • The ports to expose and to which ports on the host machine to map them (host-port:container-port)
      • ports:
              - "3000:3000"
    • Which folders from the host machine should be shared to the container, here we are using the Volume Trick (Which I've tested and works everywhere but on the Docker toolbox), it will allow us to make changes to our app code and still work.
      • volumes:
              - ./web-site:/usr/src/app
              - /usr/src/app/node_modules
    • Declare that we require the mongo container to be up and running before the current one
      • depends_on:
              - "mongo"
    • Add a command to run when this container is started
      • CMD ["node", "index.js"]
  • Our database service: mongo
    • The name of each service, used to identify each service and connect to them (the database connection should be: mongodb://mongo/test):
      • mongo
    • The name of the image that we want to reuse from dockerhub
      • image: docker-node-express-mongoapp
    • The ports to expose for this particular container
      • ports:
              - "27017:27017"
  • An optional but useful service for browsing our database: adminmongo
    • The name of each service (doesn't need to have the same name as the service as seen for the first service):
      •  adminmongo
    •  The name of the image that we want to reuse from dockerhub
      • image: "mrvautin/adminmongo"
    • The ports to expose for this particular container
      • ports:
              - "1234:1234"

Build & Run

  • Build the container:
    • docker-compose build
  • Run the container
    • docker-compose up
  • If you don't know the ip for your newly created node+express app use the ip used by the docker machine
    • docker-machine ip
  • Open the app in your browser
    • http://THE-IP:3000/testFind
  • If you want to browse the database open the mongo admin and add "mongodb://mongo/test" as the database connection and choose whatever name you like
    • http://THE-IP:1234/

Resources

Dockerizing a Node.js web app
Lessons from Building a Node App in Docker

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