Docker Hands-on: Learn Docker Compose File with Nodejs, Flask, PostgreSQL

In the previous post, we mentioned about the Docker tutorial in.

• https://dev.to/omerberatsezer/docker-tutorial-dockerfile-commands-container-images-volume-network-docker-compose-2p9h

This time, we are starting to run sample projects: Focusing on the Docker Compose file with Nodejs, Flask, PostgreSQL images to implement different tiers:

• frontend (nodejs with expressjs),
• backend (flask),
• database (postgresql).

It shows:

• how to run multiple containers
• how to run container in sequential with depends_on
• how to run containers in same network
• how to create volumes in compose file
• how to implement port-forwarding

GitHub Code Repo: https://github.com/omerbsezer/Fast-Docker/tree/main/hands-on-sample-projects/full-stack-app

Project structure:

project-root/
├── docker-compose.yaml
├── frontend/
│   ├── package.json
│   ├── index.js
│   ├── index.html
│   ├── Dockerfile
├── backend/
│   ├── app.py
│   ├── requirements.txt
│   ├── Dockerfile

• Create frontend directory, create Dockerfile:

FROM node:18
WORKDIR /home/app
COPY . .
EXPOSE 3000
RUN npm install
CMD ["npm", "start"]

• Create index.html:

  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Frontend</title>


  <h1 id="Frontend-is-working">Frontend is working!</h1>

• Create index.js (express js):

const express = require("express");
const app = express();
const port=3000;

app.get("/", (req, res) => {
res.sendFile(__dirname + "/index.html");
})

app.listen(port, () => {
  console.log(`running at port ${port}`);
});

• Create package.json:

{
  "name": "nodejsapp",
  "version": "1.0.0",
  "description": "nodejsapp description",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "node index.js"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "express": "^4.17.3"
  }
}

• Then, create backend directory, and create Dockerfile:

FROM python:3.11
WORKDIR /usr/src/app
COPY . .
RUN pip install -r requirements.txt
EXPOSE 5000
CMD ["python", "app.py"]

• Create backend app with flask:

from flask import Flask, jsonify

app = Flask(__name__)

@app.route('/')
def home():
    return "Backend is working!"

@app.route('/api', methods=['GET'])
def api():
    return jsonify({"message": "Hello from the backend!"})

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=5000)

• Create requirements.txt:

flask

• Finally create docker-compose.yaml on top of backend and frontend directories:

services:
  frontend:
    build:
      context: ./frontend
    container_name: frontend
    ports:
      - "3000:3000"
    volumes:
      - ./frontend:/usr/src/app
    depends_on:
      - backend

  backend:
    build:
      context: ./backend
    container_name: backend
    ports:
      - "5000:5000"
    volumes:
      - ./backend:/usr/src/app
    command: sh -c "pip install -r requirements.txt && python app.py"

  db:
    image: postgres:15
    container_name: db
    environment:
      POSTGRES_USER: user
      POSTGRES_PASSWORD: password
      POSTGRES_DB: mydatabase
    volumes:
      - db_data:/var/lib/postgresql/data
    ports:
      - "5432:5432"

volumes:
  db_data:

• Then, run command on where the docker-compose.yaml:

user@docker:~$ docker compose up -d
[+] Running 4/4
 ✔ Network node_default  Created                                                                                                                                                                            0.1s
 ✔ Container db          Started                                                                                                                                                                            0.7s
 ✔ Container backend     Started                                                                                                                                                                            0.7s
 ✔ Container frontend    Started  

• Then, check frontend, backend with curl:

user@docker:~$ curl http://localhost:3000



  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Frontend</title>


  <h1 id="Frontend-is-working">Frontend is working!</h1>


user@docker:~$ curl http://localhost:5000/api
{"message":"Hello from the backend!"}

user@docker:~$ curl http://localhost:5000
Backend is working!

• Finally, stop containers:

user@docker:~$ docker ps -a
CONTAINER ID   IMAGE           COMMAND                  CREATED              STATUS              PORTS                                       NAMES
3e51751b546c   node-frontend   "docker-entrypoint.s…"   About a minute ago   Up About a minute   0.0.0.0:3000->3000/tcp, :::3000->3000/tcp   frontend
d8d28325ce10   postgres:15     "docker-entrypoint.s…"   About a minute ago   Up About a minute   0.0.0.0:5432->5432/tcp, :::5432->5432/tcp   db
04c1d04a5668   node-backend    "sh -c 'pip install …"   About a minute ago   Up About a minute   0.0.0.0:5000->5000/tcp, :::5000->5000/tcp   backend
user@docker:~$ docker compose down
[+] Running 4/4
 ✔ Container frontend    Removed                                                                                                                                                                            1.0s
 ✔ Container db          Removed                                                                                                                                                                            0.5s
 ✔ Container backend     Removed                                                                                                                                                                           10.5s
 ✔ Network node_default  Removed                                                                                                                                                                            0.2s
user@docker:~$ docker ps -a
CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES

Conclusion

This post shows how to create Docker compose file using sample frontend (express.js), backend (flask), database (postgresql) apps. Please have a look below menu for other Docker content, if you haven't seen before.

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