Kiran Pawar's Blog
Day 01: Containers vs VMs | Docker Architecture, Installation, Networking, and Commands

Day 01: Containers vs VMs | Docker Architecture, Installation, Networking, and Commands

Kiran Pawar's photo
Kiran Pawar
·

4 min read

Table of contents

Understanding Hardware and Software Components

Before diving into Docker and containers, let’s understand the key hardware and software components that make up a computing environment.

Hardware Components:

  • CPU (Central Processing Unit): The brain of the computer responsible for executing instructions.

  • RAM (Random Access Memory): Temporary storage for active processes and applications.

  • Hard Drive (HD): Permanent storage for operating systems, applications, and data.

  • Graphic Cards: Dedicated hardware for rendering images and video.

Software Components:

  • Operating System (OS): The core software managing hardware resources and applications.

  • Applications: Software programs that users interact with, such as browsers, editors, or recorders.

The Kernel

The kernel is the core part of an operating system, acting as a bridge between software and hardware. It converts software requests into hardware instructions, allowing applications to run efficiently.

Container Runtimes

Container runtimes are essential for running containers. Common container runtimes include:

  • ContainerD (Used in production environments)

  • Docker (Preferred for local development and testing)

  • CRI-O (Used in Kubernetes clusters)

Note: Developers often use Docker for local testing(KIND CLUSTER), whereas production environments favor ContainerD for better performance and security.

Containers vs Virtual Machines (VMs)

Virtual Machines (VMs)

  • VMs are full-fledged operating systems running on a hypervisor.

  • Each VM has its own dedicated OS, libraries, and dependencies.

  • VMs are heavy and take longer to boot due to the full OS load.

  • Highly isolated environments ensuring strong security.

Containers

  • Containers share the same OS kernel but provide isolated environments for applications.

  • They are lightweight and start quickly since they don’t require a full OS.

  • Less isolated compared to VMs but provide efficient resource utilization.

Docker Architecture

Docker is a platform that allows developers to package applications and their dependencies into lightweight containers.

Key Components:

Docker Client

  • Acts as the command-line interface for Docker.

  • Sends commands to the Docker Daemon.

  • Example commands: docker build, docker run, docker pull

Docker Daemon

  • Runs on the host system and manages containers.

  • Handles container lifecycle, images, networks, and storage.

Docker Registry

  • A storage system for Docker images.

  • Docker Hub is a public registry where users can find and share container images.

  • Organizations use private registries to manage internal container images securely.

Docker Architecture

Installing Docker & Networking

To install Docker on Linux:

curl https://get.docker.com/ | bash

Docker Network Types

  • Bridge Network: Default network mode for containers on a single host, allowing communication between containers.

  • Host Network: Removes isolation between the container and host network, providing direct access to the host’s networking.

  • None Network: Disables networking for the container, providing a fully isolated environment.

Basic Docker Commands

Checking Docker Installation

docker version

Listing Namespaces

lsns  # List all namespaces
lsns -t pid  # List only PID namespaces

Running a Container

docker run --name app1 nginx:latest

Running a Container in the Background

docker run -d --name app1 nginx:latest

Creating Multiple Containers

for i in {1..10}; do docker run -d nginx:latest; done

Listing Running Containers

docker ps

Stopping All Containers

docker stop $(docker ps -aq)

Deploying and Removing a Container

docker run --rm -d --name app1 nginx:latest

Inspecting a Container

docker inspect app1

Port Forwarding

docker run --rm -d --name app1 -p 8000:80 nginx:latest

Viewing Container Logs

docker logs app1 -f

Install jq tool to see logs in more user friendly way

Conclusion

Docker simplifies application deployment by using lightweight containers that share the same OS kernel while maintaining process isolation. Understanding Docker's architecture, networking, and commands is crucial for managing containerized applications efficiently. Stay tuned for the next blog in this series, where we dive deeper into Docker images and container orchestration!