Program – 1
Build a Docker Container from a Custom Dockerfile

Project Structure
Program-1/
 ├── Dockerfile
 ├── app.py
 └── requirements.txt

Step 1: Create Project Directory

Command:

mkdir Program-1
cd Program-1

Step 2: Create Dockerfile

Command:

nano Dockerfile


Content of Dockerfile:

# This is a Dockerfile
# Dockerfile is a set of instructions that Docker
# uses to build a container image

# Use a slim Python base image
FROM python:3.9-slim

# Set the working directory inside the container
WORKDIR /app

# Copy the requirements file and install dependencies
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# Copy the application code
COPY . .

# Set Flask environment variables
ENV FLASK_APP=app.py
ENV FLASK_RUN_HOST=0.0.0.0
ENV FLASK_RUN_PORT=5000

# Expose the port the Flask app will run on
EXPOSE 5000

# Define the command to run the Flask application
CMD ["flask", "run"]

Step 3: Create Python Application File

Command:

nano app.py


Content of app.py:

from flask import Flask

app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello, Docker!"

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

Step 4: Create Requirements File

Command:

nano requirements.txt


Content of requirements.txt:

flask

Step 5: Build Docker Image

Command:

docker build -t program-1 .

Step 6: Verify Docker Image

Command:

docker images

Step 7: Run Docker Container

Command:

docker run -d -p 5000:5000 --name flask-container program-1

Step 8: Verify Running Container

Command:

docker ps

Step 9: Test the Application

Open a web browser and enter:

http://localhost:5000


Output:

Hello, Docker!

Step 10: Stop the Docker Container

Command:

docker container stop flask-container

Step 11: Remove the Docker Container

Command:

docker container rm flask-container

Step 12: Remove Docker Image

Command:

docker image rm program-1