Difference between Dockerfile and Docker Compose

Dockerfile and Docker Compose are both integral parts of the Docker ecosystem, but they serve different purposes and have distinct functionalities:

• Dockerfile:
  • Dockerfile is a text file that contains a set of instructions to build a Docker image.
  • It defines the environment inside a Docker container, including the base image, dependencies, environment variables, and commands to run when the container starts.
  • Dockerfile is essentially a blueprint for creating Docker images.
  • It allows you to automate the process of creating Docker images, making it easy to reproduce the same environment across different systems.
  • Dockerfile is primarily used for building single containers.

Example of a Dockerfile:

# Use an official Python runtime as the base image
FROM python:3.9-slim

# Set the working directory in the container
WORKDIR /app

# Copy the current directory contents into the container at /app
COPY . /app

# Install any needed dependencies specified in requirements.txt
RUN pip install --no-cache-dir -r requirements.txt

# Make port 80 available to the world outside this container
EXPOSE 80

# Define environment variable
ENV NAME World

# Run app.py when the container launches
CMD ["python", "app.py"]

• Docker Compose:
  • Docker Compose is a tool for defining and running multi-container Docker applications.
  • It uses a YAML file (docker-compose.yml) to define the services, networks, and volumes required by the application.
  • Docker Compose allows you to define the configuration of multiple containers, their interconnections, and dependencies in a single file.
  • It simplifies the management of complex applications by allowing you to start, stop, and manage multiple containers with a single command.
  • Docker Compose is particularly useful for development and testing environments where you need to spin up multiple interconnected containers quickly.

Example of a Docker Compose file (docker-compose.yml):

version: '3'
services:
  web:
    build: .
    ports:
      - "5000:5000"
    volumes:
      - .:/code
  redis:
    image: "redis:alpine"

📝Summary: while Dockerfile is used to build Docker images, Docker Compose is used to define and manage multi-container Docker applications. They work together to streamline the process of containerization and deployment.