How to deploy a simple Node.js+MongoDB app

Clone a Node.js application from GitHub

First, clone from the following URL to Ubuntu VM:

https://github.com/potikanond/docker-node-sample3.git

On Ubuntu VM run the following command:

` $ git clone https://github.com/potikanond/docker-node-sample3.git `

This will clone the application from GitHub to docker-node-sample3 directory.

Review the Node.js application

package.json:

{
  "name": "docker-node-mongo",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "node index.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "body-parser": "^1.18.3",
    "ejs": "^2.6.1",
    "express": "^4.16.3",
    "mongoose": "^5.2.7"
  }
}

Dependencies:

• express : a Node.js framework for web application (and api) development.
• ejs : Embedded JavaScript template is one of a Node.js template engines for generate HTML using JavaScript.
• body-parser : a middleware for Node.js, used to parse incoming web request, help extracting passing parameters.
• mongoose : a library for Node.js to work with MongoDB.

Start the Node.js application right way?

The answer is NOT at this step. This application stores and retrieves data on MongoDB, therefore, we need to configure MongoDB first.

But if you really want to start the Node.js application, we need to install Node.js on the Ubuntu VM. After that, go into the docker-node-sample3 directory and enter the following command:

` $ npm start `

If we do not have MongoDB then this would give us an ERROR:

$ npm start

> docker-node-mongo@1.0.0 start /Users/dpotikan/workspace/tutorial-docker/docker-node-sample3
> node index.js

Server running...
{ MongoNetworkError: failed to connect to server [mongo:27017] on first connect 
  [MongoNetworkError: getaddrinfo ENOTFOUND mongo mongo:27017] ... }

With Docker, we will NOT install Node.js on the docker host but we will create a Node.js container and run the application inside.

Create a docker image for the Node.js application

First, create a Dockerfile inside the docker-node-sample3 directory.

Dockerfile:

FROM node:10-alpine

WORKDIR /usr/src/app

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 3000

CMD ["npm", "start"]

For more detail on dockerizing a Node.js web app, see the following link: https://nodejs.org/en/docs/guides/nodejs-docker-webapp/

Create .dockerignore file in the same directory as the Dockerfile

.dockerignore:

node_modules
npm-debug.log

This will prevent local_modules and debug logs from being copied onto your Docker image and overwriting modules installed within your image.

Building your Node.js docker image

Use the docker image build ... command to build and tag image.

$ docker image build -t cpe405/example33 .
Sending build context to Docker daemon  148.5kB
Step 1/7 : FROM node:10-alpine
 ---> 4e50ad7c0e0b
Step 2/7 : WORKDIR /usr/src/app
 ---> Running in 5103a44253d3
Removing intermediate container 5103a44253d3
 ---> 792d79e04737
Step 3/7 : COPY package*.json ./
 ---> b2e4d3253e7f
Step 4/7 : RUN npm install
 ---> Running in 5c75c3eb9927
npm WARN docker-node-mongo@1.0.0 No description
npm WARN docker-node-mongo@1.0.0 No repository field.

added 80 packages from 62 contributors and audited 181 packages in 6.483s
found 0 vulnerabilities

Removing intermediate container 5c75c3eb9927
 ---> 0bd134e0855a
Step 5/7 : COPY . .
 ---> da43997f294f
Step 6/7 : EXPOSE 3000
 ---> Running in 7467dab066a3
Removing intermediate container 7467dab066a3
 ---> 23348db6b2bc
Step 7/7 : CMD [ "npm", "start" ]
 ---> Running in 15a2309daf6f
Removing intermediate container 15a2309daf6f
 ---> 5e97c2c283d5
Successfully built 5e97c2c283d5
Successfully tagged cpe405/example33:latest

If we would create and start a container from this image without MongoDB, there would be ERROR as shown before.

$ docker container run -p 8080:3000 cpe405/example33

> docker-node-mongo@1.0.0 start /usr/src/app
> node index.js

Server running...
{ MongoNetworkError: failed to connect to server [mongo:27017] on first connect [MongoNetworkError: getaddrinfo ENOTFOUND mongo mongo:27017] ... }

Start the application properly

To start the application properly. First, start the MongoDB container:

` $ docker container run -d –name my_mongo -p 27017:27017 mongo:4.0.1-xenial `

We will use the mongo container’s name, my_mongo, for linking with the Node.js container. Next, start the Node.js container (in foreground) and link to the MongoDB container.

$ docker container run -p 8080:3000 --link my_mongo:mongo cpe405/example33

> docker-node-mongo@1.0.0 start /usr/src/app
> node index.js

Server running...
MongoDB Connected

The --link my_mongo:mongo option tells docker to map the MongoDB container’s name, my_mongo, as the name mongo for the Node.js container. If we take a look in the index.js file, we will see that mongoose use the name mongo to refer to MongoDB container.

index.js:

...
mongoose
  .connect(
    'mongodb://mongo:27017/docker-node-mongo',
    { useNewUrlParser: true }
  )
  .then(() => console.log('MongoDB Connected'))
  .catch(err => console.log(err));
...

Now, we can access the Node.js app by http://localhost:8080

Summary

To deploy the Node.js app, we need to manually start a MongoDB container first then the Node.js app container. Next we will learn how to use docker-compose tool to deploy the app.