Intro

My notes on containers, such as Docker.

Documentation

• Titus: Introducing Containers to the Netflix Cloud

Tips And Notes

• Another way to package and deliver applications.

• Keep applications isolated, which makes the portable to different environments (same OS but different versions of the OS).

• Not the same as a VM. Containers concentrate on application and isolation.

• Worry about scaling and sizing of container from the beginning.

• Worry about data persistent.  Where would you keep the container's data?  Containers are short-term (ephemeral).
  
  

Benefits Of Containers

• Agility

• Scalability/high availability,

• Cost optimization

• Portability (can be moved between on-prem or any cloud provider platform).

  • Container images used for local development are identical to those that are run in productio

• Allows building of Immutable Infrastructure. 

• Once an application is in production, it cannot be changed or modified

•  Updates require proper change controls and code review. 

• Enables faster mean time to revenue.

• Better distributed computing capabilities.  Application can be divided into many different domains and each scaled separately

• Lightweight when compared to VMs.

  • Can boot faster

  • Smaller footprint size.

  • Ease of patching.

  • Developer agility.

  • Containers are lightweight, which makes building and deploying them faster than with VM infrastructure

Disadvantages of Containers

• Higher cost (security, tools, skills, time)

• More complex, harder to debug.  More DevOps required

• Lack of support

Use Cases

Containers can be used in

• CI/CD automation, 

• autoscaling microservices 

• containers as a service,

• hybrid cloud architectures.

Layers

• Containers use a layered approach.

• Use a union file system which allows files to remain independent from other containers

• Operating systems, applications, and libraries all contained in layers. 

• Layers are cached for fast building.

• Share OS

Container Stack Architecture

Open

Container EcoSystem

Open

Docker

• Docker is the largest player. They're a standard and a company. 

Rocket

Rocket from CoreOS was built in response to security concerns with Docker because they were providing root access to the demon, which created risk.