How to create Containers with docker

Create a folder:

simple-docker-app

Inside it, create 3 files:

simple-docker-app/
├── app.py
├── requirements.txt
└── Dockerfile

Step 2 — app.py

from flask import Flask

app = Flask(__name__)

@app.route('/')
def home():
    return "Hello! This app is running inside a Docker container."

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

Step 3 — requirements.txt

flask

Step 4 — Dockerfile

FROM python:3.10-slim

WORKDIR /app

COPY requirements.txt .
RUN pip install -r requirements.txt

COPY . .

CMD ["python", "app.py"]

Step 5 — Build Docker Image

Open terminal in this folder:

docker build -t simpleapp:v1 .

Check image:

docker images

Step 6 — Run Container

docker run -p 5000:5000 simpleapp:v1

Step 7 — Open in Browser

Open:

http://localhost:5000

You will see:

Hello! This app is running inside a Docker container.

Container 1 — Nginx Website (HTML only)

Files

nginx-app/
└── index.html

index.html

<h1>Nginx running inside Docker</h1>

Dockerfile

FROM nginx:alpine
COPY index.html /usr/share/nginx/html/index.html

Build & Run

docker build -t nginxapp .
docker run -p 8080:80 nginxapp

Open: http://localhost:8080

Container 2 — Python Script Container (prints output)

Files

python-script/
├── script.py
└── Dockerfile

script.py

print("Python running inside Docker container")

Dockerfile

FROM python:3.10-slim
COPY script.py .
CMD ["python", "script.py"]

Build & Run

docker build -t pyscript .
docker run pyscript

Container 3 — Node.js Web App

Files

node-app/
├── app.js
└── Dockerfile

app.js

const http = require('http');
http.createServer((req,res)=>{
  res.write("Node.js app in Docker");
  res.end();
}).listen(3000);

Dockerfile

FROM node:18-alpine
COPY app.js .
CMD ["node", "app.js"]

Build & Run

docker build -t nodeapp .
docker run -p 3000:3000 nodeapp

Open: http://localhost:3000

Container 4 — MySQL Database Container

(No files needed)

Run directly

docker run -d \
  --name mysqlcontainer \
  -e MYSQL_ROOT_PASSWORD=root123 \
  -p 3306:3306 \
  mysql:8

Check running:

docker ps