Assuming you are on a Linux system, let's create a temp directory.

mkdir /tmp/express

And move into the temp directory.

cd /tmp/express

Use the npm init command to create package.json.

npm init -y

Use npm install to install the express module.

npm install express

package.json should have the following.

{
  "name": "express-docker",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "express": "^4.19.2"
  }
}

Create a file named Dockerfile that contains the following.

FROM node:18-alpine
WORKDIR /src
COPY . .
RUN npm install
CMD [ "node", "index.js" ]
EXPOSE 12345

You should now have the following files in your present working directory.

├── Dockerfile
├── package.json

On your Docker server, use the docker build command to create the Node.js Express image.

sudo docker build --file Dockerfile --tag nodejs-express:18-alpine .

The docker images command should return something like this.

~]$ sudo docker images
REPOSITORY        TAG          IMAGE ID       CREATED         SIZE
nodejs-express    18-alpine    824127ec51d1   1 minute ago    189MB

Create /tmp/index.js that contains the following.

const express = require("express")
const app = express()
const timestamp = () => Date()

app.get('/', (req, res) => {
  console.log(`${timestamp()} Hello Console`)
  res.send(`${timestamp()} Hello World`)
})

app.listen(12345)
console.log(`Node.js app is up and running!`);

The docker run command can be used to create and start a Docker container from the Node.js Express image with index.js.

sudo docker run \
--name nodejs-express \
--publish 0.0.0.0:12345:12345 \
--detach \
--volume /tmp/index.js:/src/index.js \
nodejs-express:18-alpine

The docker container ls command should show the container is up and running.

~]$ sudo docker container ls
CONTAINER ID   IMAGE                      COMMAND                  CREATED        STATUS         PORTS                         NAMES
c19d5eab9a75   nodejs-express:18-alpine    "docker-entrypoint.s…"  1 minute ago   Up 1 minute    0.0.0.0:12345->12345/tcp   nodejs-express

The docker logs command should return something like this

~]$ sudo docker logs nodejs-express
NodeJS app is up and running!

Go to http://<your Docker servers hostname or IP address>:12345/ and the following should be displayed.

The docker logs command should now include "Hello Console".

]$ sudo docker logs nodejs-express
NodeJS app is up and running!
Fri Jul 05 2024 00:06:35 GMT+0000 (Coordinated Universal Time) Hello Console