Windows Containers (Part 1)

Posted on by hemanthbidare

INTRODUCTION TO CONTAINERS

Container is an isolated, resource controlled and portable environment.

It contains

  • OS
  • Application/software you developed
  • Dependencies to run the application
  • Environment variables

Microsoft offers two different types of windows containers

  1. Windows Server Container based on the windows server core image
  2. Hyper-V container based on the windows nano server image
    • They are run by highly optimized VM, so the provide a full secure isolation
    • Kernel of the Hyper-V container host is not shared with other Hyper-V containers.
    • Hyper-V containers are managed by Docker.
    • Booting Hyper-V containers takes longer than windows server container.

Lets understand the difference between the Containers and VMs.

Virtual Machines Containers
Maintained by Hypervisor Maintained by Docker Engine
Guest OS consume lot of HDs space/RAM No guest OS
VMs include the application, the necessary binaries and libraries and an entire guest OS –all of which can amount  to tens of GBs Containers include the application and all of its dependencies but share the kernel with other containers, running as isolated processes in user space on the OS.

 

The below figure gives the good understanding about containers and VMs discussed above.

vm_vs_containers

Some of the Container Jargons or terms are important to understand before we start using Containers.

  • Container Host:Physical or Virtual computer system configured with the Windows Container feature.
  • Container Image: A container image contains the base operating system, application, and all the application dependencies that are needed to quickly deploy a container.
  • Container OS Image: The container OS image is the operating system environment.
  • Container Registry: Container images are stored in a container registry, and can be downloaded on demand. It is a place where container images are published. A registry can be remote or on-premises. Eg: Docker Hub
  • Docker Engine: It is the core of the Docker platform. It is a lightweight container runtime that builds and runs your container.
  • Docker file: Docker files are used by developers to build and automate the creation of container images. With a Docker file, the Docker daemon can automatically build a container image.

 

In the next part we will install docker for windows and get our hands dirty with containerization.

Leave a comment