Docker Lecture

Introduction to Docker

• Importance of learning Docker for open-source contributions.
• Docker is essential for developers, DevOps engineers, and full-stack engineers.
• Movement towards microservices architecture and widespread adoption of Docker.
• This is part one of a two-part Docker series.

Topics Covered in Part One

• Problem statement Docker solves.
• Installation of Docker on a local machine.
• Understanding images and containers.
• Running Ubuntu images in containers.
• Running multiple containers.
• Port mapping.
• Environment variables.
• Dockerizing a full-stack Node.js application.
• Introduction to Docker Compose.

Problem Statement

• Developers often struggle with setting up consistent development environments.
• Differences in tool versions and configurations across different machines.
• Difficulty in replicating environments for new team members or deploying to the cloud.
• Docker solves this by using containerization to create consistent environments.

Installation

• Install Docker CLI and Docker Desktop.
• Commands to check installation:
  • docker --version
  • docker run hello-world

Images and Containers

• Images: Templates for creating containers with specific software and configurations.
• Containers: Instances of images that run applications in isolated environments.
• Commands to interact with containers:
  • docker run to create and start a container.
  • docker ps to list running containers.
  • docker images to list images.
  • docker exec to run commands inside a running container.

Creating and Running Containers

• Pulling and running Ubuntu image:
  • docker run -it ubuntu
• Understanding container isolation.

Port Mapping

• Exposing container ports to the host machine.
• Example: Running a web server inside a container and accessing it from the host machine.
  • docker run -p 8000:8000 [IMAGE_NAME]

Environment Variables

• Setting environment variables inside containers:
  • docker run -e KEY=VALUE [IMAGE_NAME]

Dockerizing a Node.js Application

• Creating a simple Node.js application.
• Writing a Dockerfile to create an image for the application.
• Building and running the Docker image:
  • docker build -t app-name .
  • docker run -p 4000:4000 app-name

Docker Compose

• Simplifying multi-container Docker applications.
• Writing a docker-compose.yml file.
• Starting multiple services with a single command:
  • docker-compose up

Conclusion

• Importance of understanding Docker for modern development workflows.
• Look forward to part two for advanced Docker concepts like networking and multi-stage builds.