Docker vs Virtual Machines (VMs)

docker_vs_virtualmachine.MD

Docker vs Virtual Machines (VMs)

Introduction

• Overview of Docker and Virtual Machines (VMs).
• Agenda: Definitions, how they function, and guidance on workload suitability.

Common Themes

• Both Docker and VMs address the concept of virtualization.

Virtualization

• Virtualization: Using software to create an abstraction layer.
• VMs use a hypervisor as the abstraction software.

Hypervisors in VMs

• Hypervisor: Helps VMs emulate a physical computer.
• Manages resource allocation between VMs on a single host.

Structure of VMs

• Each VM runs its own operating system and has virtual hardware (CPU, storage).

Introduction to Docker

• Docker: An open source platform for containerization.
• Containers package applications and dependencies into portable units.

Docker's Approach

• Docker containers virtualize the operating system, not the hardware.
• Containers include the application, libraries, and dependencies.

Docker Components

• Docker Engine: Manages the lifecycle of containers.
• Handles container creation, running, and orchestration.
• Interacts with the host kernel for resource allocation and isolation.

Resource Management in Docker

• Uses cgroups (control groups) for resource allocation.
• Namespaces for restricting container access and visibility on the system.

Docker Images

• Standalone, executable packages containing software, runtime, libraries, and settings.
• Built using Docker files, which are documents with image creation instructions.

Docker Containers

• Instances of Docker images running in the Docker engine.
• Isolated environments with necessary components for specific applications.

VMs and Hypervisors

• Hypervisors come in two types: Type 1 (bare metal) and Type 2 (hosted).
• Virtual hardware in VMs includes components like CPU, memory, and storage.

Guest Operating Systems in VMs

• Each VM can have a different guest OS from the host and other VMs.

Use Cases for VMs

• Running diverse operating systems.
• Isolation: Each VM has a separate kernel and OS.
• Legacy applications: Suitable for specific OS versions or configurations.

Use Cases for Docker Containers

• Ideal for microservices-based applications.
• Rapid development and deployment: Suited for agile and CI/CD practices.
• Resource efficiency: Smaller footprint, allows more containers on the same hardware.

Selection Criteria

• Choose based on application and infrastructure needs.
• Hybrid environments: Legacy apps on VMs, modern apps in Docker containers.
• Both technologies have transformed application deployment and management.