Containerization – Docker 

What is Containerization?
Containerization is a lightweight alternative to full machine virtualization that involves
encapsulating an application in a container with its own operating environment.

Containers are essentially operating system sandboxes that are hosted on full operating
systems. In the case of Windows containers, these are all hosted on Windows Server.
Each container contains the minimal amount of resources, and any operating system-
specific resources are gathered from the operating system “beneath” them. Windows
containers have their own networking, file system and registry. When it needs the ability
to interact with these systems, it will use the hosting operating system.

Containers Vs Virtual Machines

Containers and virtual machines (VMs) are complementary. VMs excel at providing extreme
isolation (for example with hostile tenant applications where you need the ultimate break out
prevention). Containers operate at the process level, which makes them very lightweight
and perfect as a unit of software delivery. While VMs take minutes to boot, containers can
often be started in less than a second.

Container
s vs VMs

Advantages of containerization
Containerization gained prominence with the open source Docker, which developed a
method to give containers better portability allowing them to be moved among any
system that shares the host OS type without requiring code changes. With Docker
containers, there are no guest OS environment variables or library dependencies to
manage.
Proponents of containerization point to gains in efficiency for memory, CPU
and storage as key benefits of this approach, compared with traditional virtualization.
Because containers do not have the overhead required by VMs separate OS instances
it is possible to support many more containers on the same infrastructure. As such,
containerization improves performance because there is just one OS taking care of
hardware calls.

A major factor in the interest in containers is they can be created much faster than
hypervisor-based instances. This makes for a much more agile environment and
facilitates new approaches, such as microservices and continuous integration and
delivery.

Why to use Containers?

Containers have some characteristics that make them a favorable choice for hosting
workloads on cloud, which are described in the sections that follow.

Agility
Because starting a new container instance is essentially the same as starting a new
process, you can start containers quickly usually in time frames less than a second.

Compute Density
Because container instances are just processes, you can run a large number of
container instances on a single physical server or VM. A higher compute density means
that you can provide cheaper and more agile compute services to your customers.

Decouple compute and resource

Another major benefit of using containers is that the workloads running in them are not
bound to specific physical servers or VMs. Traditionally, after a workload is deployed,
it’s pretty much tied to the server where it’s deployed. If the workload is to be moved to
another server, the new one need to be repurposed for the new workload, which usually
means the entire server, needs to be rebuilt to play its new role in the datacenter. With
containers, servers are no longer assigned with specific roles. Instead, they form a
cluster of CPUs, memory, and disks within which workloads can roam almost freely.

How can I use containers?

There are a different ways to get started with Windows Server containers. You may
choose a cloud service such as Azure Container Service. This prevents from having to
either bring up physical hardware or even provision a new virtual machine to host a
container on. Or, by using PowerShell, any machine running Windows Server 2016 can
be configured to host containers.

There are many tools available in market which will help you build containers.
1.    Docker 2.    Packer

3.    Kubernetes 4.    Mesos

5.    Rocket (rkt) 6.    CloudSlang

7.    Marathon 8.    Nomad

9.    Swarm 10.  Fleet

11.  OpenVZ 12.  Rancher

13.  Containership 14.  Solaris Containers

15.  Tectonic

Docker overview
Docker is an open platform for developing, shipping, and running applications. Docker
enables you to separate your applications from your infrastructure so you can deliver
software quickly. With Docker, you can manage your infrastructure in the same ways
you manage your applications. By taking advantage of Docker’s methodologies for
shipping, testing, and deploying code quickly, you can significantly reduce the delay
between writing code and running it in production.
 Docker Architecture

Docket Architecture

 Docker Client: Is a command line interface

 The Docker daemon(dockerd): It listens for Docker API requests and manages Docker objects
such as images, containers, networks, and volumes. A daemon can also communicate with
other daemons to manage Docker services.

 Docker Host: Is a host VM/Machine with O/S Linux or Windows running docker daemon.

 
 Docker Image: Is the definition with single file.

 Docket Container: Is an instance of an image, there can be many instances of image.

 Docker Hub: Is a collection of reusable images. 50K+ images of WordPress, Redis, MySql and
your images. We can use public hub or can create private hub

 Docker Resigtries: A Docker registry stores Docker images. Docker Hub and Docker Cloud are
public registries that anyone can use, and Docker is configured to look for images on Docker
Hub by default. You can even run your own private registry.

 Services: allow you to scale containers across multiple Docker daemons, which all work
together as a swarm with multiple managers and workers. Each member of a swarm is a Docker
daemon, and the daemons all communicate using the Docker API.

Create docker container from  image in docker Hub 

For detailed information about Containerization and Docker please
read Containerization – Docker – Part1

This article focuses on containerization using Windows Azure and Docker.

Note: Installation of Docker requires computer system (physical or virtual) running

Windows Server 2016.

Prerequisite: Create Windows Server 2016 VM in Azure

Create Windows Server 2016 VM

  

Steps by step installation of docker in VM

1. Install Docker

To install Docker we need MicrosoftDockerProvider. The provider enables the

containers feature on your machine. You also install Docker which requires a reboot.
Docker is required in order to work with Windows containers. It consists of the Docker
Engine and the Docker client.

 Open an elevated PowerShell session and run the following commands and run following
PowerShell command

Install-Module -Name DockerMsftProvider -Repository PSGallery –Force

Docker Microsoft Provider

 Use the PackageManagement PowerShell module to install the latest version of Docker.
PowerShell asks you whether to trust the package source ‘DockerDefault’, typeA to continue the
installation. When the installation is complete, reboot the computer.
 Install Docker
 

 Run following command to restart computer

Restart-Computer –Force

 Run following commands to update docker to most recent version

#Check the installed version with

Get-Package -Name Docker -ProviderName DockerMsftProvider

#Find the current version with

Find-Package -Name Docker -ProviderName DockerMsftProvider

#Upgrade docker with

Install-Package -Name Docker -ProviderName DockerMsftProvider -Update -Force

#Restart Docker service with

Start-Service Docker

 
Update Docker

2. Install Windows Updates

Ensure your Windows Server system is up-to-date by running with

Sconfig

Choose option 6 to Download and Install Updates. When prompted, choose option A to
download all updates.
Install Windows Updates

3. Install Your First Container

Let’s download existing .NET sample image from the Docker Hub registry and deploy a
simple container running a .Net Hello World application.

docker run microsoft/dotnet-samples:dotnetapp-nanoserver

Install .NET docker image