Docker Notes for DevOps Engineering

Table of Contents

1. Introduction to Docker

• 1.1 What is Docker?
• 1.2 Installation
• 1.3 Docker Container and Images
• 1.4 Docker Hub

2. Docker Command Line Interface (CLI)

• 2.1 Introduction to Docker CLI
• 2.2 Docker Image CLI
• 2.3 Docker Container CLI

3. Docker Custom Images

• 3.1 Dockerfile
• 3.2 Containerize a Node.js Application
• 3.3 Automatic Port Mapping
• 3.4 Pushing to Docker Hub

4. Docker Networking

• 4.1 Bridge Mode Networking
• 4.2 Host Mode Networking
• 4.3 Overlay Mode Networking
• 4.4 IPvlan and MacVlan Networking
• 4.5 None Mode Networking

5. Docker Volumes

• 5.1 Attaching Host Volumes
• 5.2 Custom Volumes

6. Docker Compose

• 6.1 Introduction to Docker Compose
• 6.2 Defining Docker Compose Files

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Docker Notes for DevOps Engineering

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1. Introduction to Docker

1.1 What is Docker?

• Definition: Docker is a platform for developing, shipping, and running applications inside lightweight, portable containers.
• Key Benefits:
  • Consistency across environments
  • Rapid application deployment
  • Resource efficiency compared to traditional VMs

1.2 Installation

• Steps to Install:

  • Windows : Use Docker Desktop (CLI + GUI)
  • Linux: Use package managers like apt or yum
  • MacOS: Docker Desktop or brew install docker

• Check Installation: Run docker --version.

  image Guide

  
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  🚥🚥🚥🚥🚥🚥🚥🚥🚥🚥

  ========================>>> Its automaticly detect the WSL Linux

  

1.3 Docker Container and Images

• Image: A lightweight, standalone, and executable software package.
• Container: An instance of an image running as an isolated process.
• Commands:

  docker pull <image-name>
  docker run <image-name>

🧫 Run Docker in WSL

1.4 Docker Hub

• A cloud-based repository to store and share Docker images.
• Usage:
  • Find public images
  • Push custom images using docker push

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2. Docker Command Line Interface (CLI)

2.1 Introduction to Docker CLI

• Purpose: Manage images, containers, and Docker resources using the terminal.
• Basic Commands:
  • docker ps – List running containers
  • docker images – List images

2.2 Docker Image CLI

• Key Commands:
  • docker pull <image> – Download an image
  • docker rmi <image> – Remove an image

2.3 Docker Container CLI

• Key Commands:
  • docker run <image> – Start a container
  • docker stop <container> – Stop a running container
  • docker logs <container> – View logs from a container

1. Running Ubuntu img in Containers
2. Multiple Containers
3. Port Mapping

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3. Docker Custom Images

3.1 Dockerfile

• Definition: A text file containing instructions to build a Docker image.
• Sample Dockerfile:

  FROM node:14
  COPY . /app
  WORKDIR /app
  RUN npm install
  CMD ["node", "app.js"]

• Command to Build:

  docker build -t <image-name> .

3.2 Containerize a Node.js Application

• Steps to:
  • Create a Dockerfile
  • Use docker build and docker run

3.3 Automatic Port Mapping

• Map ports using -p flag:

  docker run -p 3000:3000 <image>

3.4 Pushing to Docker Hub

• Authenticate: docker login
• Push Image:

  docker tag <image> <username>/<repository>
  docker push <username>/<repository>

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4. Docker Networking

4.1 Bridge Mode Networking

• Default mode. Containers share the host's networking but are isolated.
• Command:

  docker network inspect bridge

4.2 Host Mode Networking

• Shares the host network namespace.
• Useful for performance-critical apps.

4.3 Overlay Mode Networking

• Enables multi-host container communication.

4.4 IPvlan and MacVlan

• Advanced networking modes for performance and integration.

4.5 None Mode Networking

• Completely disables networking for the container.

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5. Docker Volumes

5.1 Attaching Host Volumes

• Mount directories from the host into the container.
• Command:

  docker run -v /host/path:/container/path <image>

5.2 Custom Volumes

• Named volumes for persistent storage:

  docker volume create myvolume

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6. Docker Compose

6.1 Introduction to Docker Compose

• A tool to define and run multi-container Docker applications.

6.2 Defining Docker Compose Files

• Sample docker-compose.yml:

  version: '3'
  services:
    app:
      image: node:14
      ports:
        - "3000:3000"

• Commands:

  docker-compose up
  docker-compose down

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Tables for Quick Reference

Command	Description
docker pull <image>	Download an image
docker run <image>	Create and start a container
docker ps	List running containers
docker stop <container>	Stop a running container
docker volume create	Create a named volume

Networking Mode	Description
Bridge	Default mode, isolated container networking
Host	Shares host's network namespace
Overlay	For multi-host communication