Build a Todo App with Node.Js, ExpressJs, MongoDB and VueJs - Part 3

If you have made it to Part 1 and Part 2 of this tutorial, you deserve some accolades. And If you have not, you need to check 1 and 2 out.

Let's take a moment to reflect on what we went through and how container technologies like docker could make this process easier.

In the previous tutorials, we installed Node runtime and MongoDB. The installation process was tedious and required a lot of manual efforts.

Not only that, If Bill, who has a different environment, tries to run the application, chances are the application would not run correctly. This happens most of the time because of inconsistency in environments and disparity in system libraries. Using virtualization technologies like docker ensures that your applications run the same in all environments.

This abolishes rooms for a famous saying, "It works on my machine." With docker, you can maintain a consistent environment everywhere.

What is docker?

Docker is a container platform that allows you to seamlessly build, share, and run applications in any environment. With docker, you can define instructions on how your application should be built using DockerFile.

Installing docker and docker-compose tool

Docker is very easy to install. Irrespective of your operating system, you can find a distribution that works for your type of OS. Head on to docker install page to download an executable docker file for your operating system.

Since we'll be using creating multiple containers for this application, you'll need to install docker-compose tool – a tool that lets you define and run multi-container Docker applications. Proceed to the official download page to download one for your operating system.

Creating Dockerfile for backend Service

A Dockerfile is a text file that contains a set of instructions. Docker read these instructions to build an image.

Navigate to the backend directory and create a Dockerfile.

$ cd backend
$ touch Dockerfile

Update the content of the Dockerfile with this content.

# backend/Dockerfile

FROM node:12.2.0-alpine 

WORKDIR /usr/app

COPY package*.json ./

RUN npm install

COPY . . 

CMD [ "npm", "start" ]

In this Dockerfile, we used 5 different docker commands.

• FROM allows you to specify a base image for your image. In this case, we based from node:12.2.0-alphine
• WORKDIR allows you to set the current working directory. We set the current working directory to usr/app.
• COPY: This command let you copy files, directories or remote contents into the image file system. We copied to our package.json and package.lock.json to the docker image
• RUN : This command is used to execute command in the shell. RUN command creates a new layer. We use RUN to execute npm install which installs our project dependencies.
• COPY: We used copy to copy our source code in to the container again
• CMD lets you set command to be executed when the container runs.

Let's proceed to create another Dockerfile in the frontend directory for the frontend. The commands will be simillar to the one we just created.

$ cd  frontend

$ touch Dockerfile

Update the Dockerfile you created with:

#frontend/Dockerfile

FROM node:12.2.0-alpine

WORKDIR /app

COPY package*.json ./

RUN npm install

COPY . .

CMD ["npm", "run", "serve"]

Finally, we create a docker-compose file at the root directory of the project.

version: "3"
services:
  backend:
    container_name: backend 
    build:
        context: ./backend
    depends_on:
      - db  
    volumes:
      - ./backend:/usr/app
      - /usr/app/node_modules
    environment:  
      - MONGO_URL=mongodb://db:27017/todos
      - APP_PORT=80
    ports: ['80:80'] 

  db:
    container_name: db
    image: mongo:4.0
    restart: always

  frontend:
    container_name: frontend
    build:
      context: ./frontend
    volumes:
      - ./frontend:/app
      - /app/node_modules
    ports:
      - '8080:8080'
    environment:  
      - BACKEND_URL=http://localhost/todos

In the docker-compose file, we defined all our services.

The backend container is built from the instructions defined in Dockerfile in the backend directory.

We used depends_on to specify dependencies for the container.

We used volume to share data between our local and host machine.

This is ideal for a development environment because we want to see our changes as we make them. You should not do that in production.

We defined 2 environment variables APP_PORT, MONGO_URL, and finally port 80 in the container to port 80 on our environment.

Finally, execute docker-compose up -d to bring up your containers.

If you go to http://localhost:8080, you see your app running.

You find the source code for this app on Github

Some useful links

• Docker Build: A Beginner’s Guide to Building Docker Images

• Why Docker? Creating a multi-container application with docker