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Getting Started with Windows Containers for SQL Server - Part 1

By:   |   Updated: 2019-02-14   |   Comments (4)   |   Related: 1 | 2 | 3 | 4 | 5 | 6 | More > Containers

Problem

Our company is looking at evaluating Containers to modernize our existing applications, including our SQL Server databases. I have no prior knowledge of Containers. How do I get started with Containers to help me prepare for modernizing our SQL Server databases?

Solution

Container technology solves a unique problem that every IT organization faces: reliably run software when moved from one computing environment to another. As a SQL Server DBA, this is something that we must deal with every time we migrate or upgrade our databases – from physical machine to another physical machine, from physical machine to virtual machine, from older version to newer version or from on-premises to the cloud. A more common scenario is when a developer writes T-SQL code from their development environment and promotes the code in staging environment and even production. Even with a proper change management process, this can still be an issue because there is no guarantee that the different computing environments will be the same.

Container technology – or containers, as they are more commonly known – addresses this problem. It does this by packaging an application and all of its dependencies like binaries, kernel libraries, configuration files, system tools, etc. and creating an entire runtime environment. A container image is created and packaged with the application and all of its dependencies. The image is then deployed as a container at runtime.

Virtualization versus Containers

Given the nature of containers, you might get confused as to how different they are from virtual machines. To illustrate, below is a diagram of the hypervisor architecture.

Virtualization versus Containers

Virtualization solves a totally different IT problem on its own: hardware overprovisioning. In the past, IT would provision hardware that is barely even using half of the available resource. This is wasted resource. So, instead of buying expensive hardware for a specific application without knowledge of present or future capacity, you can run them on virtual machines with minimal resources. You can scale the virtual machines up in the future if and when the workload increases. Even better, you can run multiple virtual machines on a single physical machine. The only time IT would buy hardware is when there really is a need for it.

However, virtualization came with its own sets of challenges. For one, each virtual machine requires its own copy of the operating system before you can even run applications inside them. Each operating system consumes a fair amount of hardware resources from the physical host – virtual CPU, memory and storage. Plus, if every virtual machine runs the same operating system, you are basically creating and running multiple copies of the operating system, each requiring the same amount of administrative overhead like securing, patching and monitoring. Wouldn't it be great if you only had one operating system that runs the different applications but in an isolated process, so they don't interfere with one another, much like how one application is isolated from another thru virtual machines?

This is where containers come in.

Containers Architecture

In the diagram above, you only have one operating system. The containers share the same operating system kernel with other containers, each one running as isolated processes in user space. Instead of abstracting the hardware like what virtualization does, containers abstract the operating system kernel. This reduces the amount of storage space requirement for containers, eliminating the inefficiencies of having multiple copies of the operating system running on guest virtual machines. It also significantly reduces the amount of administrative overhead necessary to manage operating systems. Plus, they use far fewer resources than virtual machines.

And since containers do not have a full-blown operating system, they can be easily started and stopped in a "just-in-time" fashion, quickly spinning up containers when the need arises. This is a huge benefit when dealing with fast software development lifecycles and having the right environment that comes with it. Imagine having a developer build an application and deploying it in a container that can be moved across different computing environments, from his workstation to a production server, while eliminating the very common "but it worked in my laptop" comment.

Linux, Containers and Docker

The idea behind containers started with virtualizing the Linux operating system kernel. This is the reason why it is very popular in the Linux community. As a SQL Server DBA who only worked with Windows in most of your career, this can be a little bit intimidating, especially if you haven't worked with Linux just yet. Don't fret. Windows Server 2016 has support for containers, so you can start working with it in a familiar environment. In fact, this tip will get you started on deploying containers on a Windows Server 2016 environment.

However, you do need to have a basic understanding of Linux to fully maximize containers.

And because containers were built to virtualize the operating system kernel, the container image needs to share the same operating system as the underlying engine. That's not to say that you cannot run both Windows and Linux containers on the same container engine, like running a Windows and Linux virtual machine on the same hypervisor. But it isn't a good idea from an operations standpoint.

In a previous tip on Run SQL Server vNext (CTP1) as a Docker Container on a Mac, you've seen how to leverage Docker with a SQL Server running in a container. But what is Docker?

Docker is a container engine developed by Docker, Inc. based on the concept of virtualizing the Linux operating system kernel. Docker is to container engine much like how VMWare is to virtualization. Learning the different docker commands to work with the Docker container engine – for SQL Server on both Windows and Linux - will be the focus of this series of tips.

Let's get started with setting up Docker on a Windows Server 2016 machine.

Setup Docker on Windows Server 2016

Here's a high-level overview of the process involved in setting up Docker and using the Windows container feature on Windows Server 2016. It is a clean installation of the operating system and directly connected to the Internet.

  1. Enable the Containers feature on Windows Server 2016
  2. Download and install the Docker-Microsoft PackageManagement provider
  3. Download and install the Docker package

Step #1: Enable the Containers feature on Windows Server 2016

To enable the Containers feature:

  • Open the Server Manager Dashboard and click the Add roles and features link. This will run the Add Roles and Features Wizard.
Configure Windows Server 2016 for Containers
  • Click thru the different dialog boxes until you reach the Select features dialog box. In the Select features dialog box, select the Containers checkbox and click Next.
Windows Add Roles and Features interface to add Containers
  • In the Confirm installation selections dialog box, select the Restart the destination server automatically if required checkbox and click Install to proceed to do the installation. When prompted with the Add Roles and Features Wizard about restarting the server automatically, click Yes.
Confirm Installation Selections for the Containers installation

Another way of installing the Containers feature is by using the Install-WindowsFeature PowerShell cmdlet.

Install-WindowsFeature –Name Containers

NOTE: Be sure to run all PowerShell commands in an elevated Administrative PowerShell command shell.

You will be prompted to restart the server to finish the installation process. Use the Restart-Computer PowerShell cmdlet to do so.

Restart-Computer
PowerShell code Install-WindowsFeature –Name Containers

Step #2: Download and install the Docker-Microsoft PackageManagement provider

Before you can install Docker, you need to use the PackageManagement provider to download and install the MicrosoftDockerProvider. This provider enables you to easily install Docker on your machine. Use the Install-Module PowerShell cmdlet for this.

Install-Module -Name DockerMsftProvider -Force

When prompted to download and install the NuGet provider, type Y to respond Yes.

PowerShell code Install-Module -Name DockerMsftProvider -Force

Step #3: Download and install the Docker package

Finally, you can use the PackageManagement PowerShell module that you downloaded and installed in Step #2 - DockerMsftProvider - to install the latest version of Docker. This includes both the Docker Engine and the Docker client. Use the Install-Package PowerShell cmdlet for this.

Install-Package -Name docker -ProviderName DockerMsftProvider -Force
Download and install the Docker package

After installing the Docker Engine, you may need to start the Docker service (or daemon, in Linux). You can use the Services management console to do this.

Start Docker Services in Windows

Alternatively, you can use the Get-Service and Start-Service PowerShell cmdlets for this.

Get-Service | Where-Object {$_.Name -like "docker*"} | Start-Service 

NOTE: You may need to reboot the server after installing Docker in order to update the environment variables to point to the C:\Program Files\Docker path so you can run Docker commands from either the command prompt or the PowerShell command shell.

Verifying Docker Installation

You can verify the Docker installation by running the docker.exe command. In future tips, we will explore the most common docker.exe commands to perform the most common tasks.

You can either use the command prompt or the PowerShell command shell to run docker.exe commands. I prefer using PowerShell so I can use the available PowerShell cmdlets when working with the output of the docker.exe commands.

Run the command below to check the version of docker installed on the server.

docker version
Docker Version in PowerShell

Here you can see the version of both the docker client and the docker engine. Obviously, the OS/Arch: property will display Windows since the Docker engine is running on a Windows Server 2016 machine.

Run the command below to display system-wide information regarding the docker installation on the server.

docker info
Docker Info PowerShell command

Congratulations! You now have a Docker engine running on your Windows Server 2016 server. In the next tip in this series, you will explore the most common docker.exe commands to perform the most common tasks.

Next Steps


Last Updated: 2019-02-14


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Monday, April 22, 2019 - 9:57:11 AM - Charlie Arehart Back To Top

Bass_player, perhaps there was a time when that was so (that Docker FOR Windows) ran only Linux containers, but that's not so anymore. It can run either. I run it on several machines, and there's an option when you right-click it in the status try to "switch to Linux containers" (or "switch to Windows containers", to reverse that).

(And for the sake of clarity--between us and for all reading along, "docker for windows" is formally named "docker desktop for windows". That's what I was referring to, and I assume it's what you mean also. Even the Docker page about it uses both terms: https://docs.docker.com/docker-for-windows/ .)

So it would seem my question to Edwin would still seem to stand: is there any particular reason that he chose the PS route (over Docker Desktop, and the flexibility that it offers)? And more important, does he see any problem for folks following along who may have done the latter, if enabled FOR Windows containers, to this latest point. :-)


Saturday, April 20, 2019 - 9:57:10 AM - bass_player Back To Top

Charlie,

There's a big difference between Docker for Windows versus Docker on Windows. Docker for Windows is a full development platform that leverages a Linux VM on Windows and, therefore, only run Linux-based containers. Docker on Windows runs the native Docker engine on the Windows platform without a Linux VM and, therefore, only run Windows-based containers.

For Windows sysadmins and SQL Server DBAs getting started with containers without the added confusion of learning Linux, Docker on Windows is the best path. This way they can leverage the knowledge and skills that they already have managing SQL Server on Windows.


Saturday, April 13, 2019 - 10:04:47 AM - Charlie Arehart Back To Top

Thanks for the series. Can you offer here why you chose to install and enable docker using the powershell cmdlets vs using the available Docker for Windows installer (and would our already using that affect how we follow on with the rest of the series)? Or might you have covered that choice elsewhere? 


Monday, February 18, 2019 - 3:54:59 AM - Kenneth Igiri Back To Top

 Thanks Sir.



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