Windows 2016 containers for portable application environment


Windows 2016 Containers are an isolated, resource controlled and portable Operating environment irrespective of the application and operating configuration that on host server Operating environment.

Such containers have existed for a long time on Unix-like operating systems, but their usage for application deployment increased following the release of Docker as an open source project in early 2013.

A Windows container act like a newly installed Operating system and can be managed using Docker. Docker provides a high-level API and tools for managing and deploying container images, and Docker Hub is a public repository of container images.

There were two container type on Windows 2016

Windows server Container: provide application isolation through process and namespace isolation technology. Windows server container share a kernel with container host and all other containers running on this host. Provide NO hostile security boundary due to this.

Container

Hyper-V Isolation: expands on the isolation provided by Windows Server Containers by running each container in a highly optimized virtual machine. In this configuration, the kernel of the container host is not shared with other containers on the same host. Designed for hostile multitenant hosting with the same security assurances of a virtual machine.

Container Fundamentals:

Container Host: – Physical or Virtual computer system configured with the Windows Container feature. Though it is a Windows feature must enable docker management layer and command-line interface using below Powershell command-lets

Install-Module -Name DockerMsftProvider -Repository PSGallery -Force
 Install-Package -Name docker -ProviderName DockerMsftProvider
 Restart-Computer -Force

Container OS Image: – Containers are deployed from images. The container OS image is the first layer in potentially many image layers that make up a container. This image provides the operating system environment.

To install Windows server core run below command on Docker shell

docker pull microsoft/windowsservercore

For nano server (Refer Nano server https://docs.microsoft.com/en-us/windows-server/get-started/getting-started-with-nano-server)

docker pull microsoft/nanoserver

Container Image: – A container image contains the base operating system, application, and all application dependencies needed to quickly deploy a container.

Docker provides a central repository called Docker Hub (https://hub.docker.com/u/microsoft/) the public containerized-application registry that Docker maintains. Container Images can be published directly on this repository to be shared with the Docker community. There are already many images hosted on the Docker Hub. For example:

  • SQL
  • WordPress
  • IIS .. etc

Container Registry: – Container images are stored in a container registry, and can be downloaded on demand.

You can run a private repository on-premise. Microsoft has its own public and official repository available via this URL: https://hub.docker.com/u/microsoft/  

Dockerfile: – a text file containing the instructions needed to create a new container image. These instructions include identification of an existing image to be used as a base, commands to be run during the image creation process, and a command that will run when new instances of the container image are deployed.

Note: Docker for Windows Server 2016 requires update “KB3176936”. You can download it from the Windows Update Website and then install manually:

http://www.catalog.update.microsoft.com/search.aspx?q=kb3176936

Why we use this?

IT Professionals can use containers to provide standardized environments for their development, QA, and production teams. They no longer have to worry about complex installation and configuration steps. By using containers, systems administrators abstract away differences in OS installations and underlying infrastructure.

For Developer’s, their desktop to a testing machine to a set of production machines, a Docker image can be created that will deploy identically across any environment in seconds.

When you containerize an app, only the app and the components needed to run the app are combined into an “image”. Containers are then created from this image as you need them. You can also use an image as a baseline to create another image, making image creation even faster. Multiple containers can share the same image, which means containers start very quickly and use fewer resources

Limitations:

  • Docker containers can only run natively on Windows Server 2016 and Windows 10. Other versions won’t work with Docker because they lack the kernel enhancements necessary to support Docker containers,
  • Some advanced networking configuration features for Docker are not yet supported because the “plumbing” required to make those features work is not complete inside the kernel,
  • Most notably, Docker containers on Windows can only run Windows apps inside the containers. In other words, you can’t run an app compiled for Linux inside a Docker container running on Windows. You would need a Windows host to do that. (And the opposite holds true: You can’t run Windows apps inside Docker containers on a Linux host.)

For URL reference

https://docs.microsoft.com/en-us/virtualization/windowscontainers/about/faq

https://docs.microsoft.com/en-us/virtualization/windowscontainers/deploy-containers/deploy-containers-on-server

https://docs.microsoft.com/en-us/virtualization/windowscontainers/quick-start/

 

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