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Docker

Docker - Introduction

1. What is Docker?​

  • Docker is an open-source platform for building, deploying, and running applications in containers.
  • Containers are lightweight, standalone, executable packages of software that include everything needed to run an application.

2. Benefits of Docker:​

  • Portability: Containers can run consistently across different environments (dev, staging, prod) and platforms (Linux, Windows, etc.).
  • Isolation: Containers are isolated from each other and from the host system, ensuring better security and resource utilization.
  • Efficiency: Containers are lightweight and share the host's OS kernel, resulting in efficient resource usage and fast startup times.
  • Consistency: Docker containers encapsulate the application and its dependencies, ensuring consistent behavior across different environments.

3. Docker Architecture:​

  • Docker Engine: The core component that manages Docker containers, images, networks, and volumes.
  • Docker Client: The command-line interface (CLI) or API used to interact with the Docker Engine.
  • Docker Registry: A service for storing and distributing Docker images.
  • Docker Objects:
    • Images: Read-only templates used to create containers.
    • Containers: Running instances of Docker images.
    • Networks: Virtual networks that connect Docker containers.
    • Volumes: Persistent data storage for containers.

4. Docker Workflow:​

  1. Build an image from a Dockerfile (text file with instructions).
  2. Push the image to a registry (e.g., Docker Hub, private registry).
  3. Pull the image from the registry.
  4. Create and run a container from the image.

5. Basic Docker Commands:​

  • docker build: Build an image from a Dockerfile.
  • docker pull: Pull an image from a registry.
  • docker run: Create and start a new container from an image.
  • docker ps: List running containers.
  • docker stop: Stop a running container.
  • docker rm: Remove a stopped container.
  • docker images: List available images.
  • docker rmi: Remove an image.

6. Use Cases:​

  • Consistent development and deployment environments.
  • Microservices architecture and application modernization.
  • Continuous Integration and Continuous Deployment (CI/CD) pipelines.
  • Multi-cloud and hybrid cloud environments.