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- Herausgeber: Packt Publishing
- Kategorie: Fachliteratur
- Sprache: Englisch
- Veröffentlichungsjahr: 2017
Windows Server Containers are independent, isolated, manageable and portable application environments which are light weight and shippable. Decomposing your application into smaller manageable components or MicroServices helps in building scalable and distributed application environments. Windows Server Containers have a significant impact on application developers, development operations (DevOps) and infrastructure management teams. Applications can be built, shipped and deployed in a fast-paced manner on an easily manageable and updatable environment.
Learning Windows Server Containers teaches you to build simple to advanced production grade container based application using Asp.Net Core, Visual Studio, Azure, Docker and PowerShell technologies. The book teaches you to build and deploy simple web applications as Windows and Hyper-V containers on Windows 10 and Windows Server 2016 on Azure. You will learn to build on top of Windows Container Base OS Images, integrate with existing images from Docker Hub, create custom images and publish to Hub. You will also learn to work with storage containers built using Volumes and SQL Server as container, create and configure custom networks, integrate with Redis Cache containers, configure continuous integration and deployment pipelines using VSTS and Git Repository. Further you can also learn to manage resources for a container, setting up monitoring and diagnostics, deploy composite container environments using Docker Compose on Windows and manage container clusters using Docker Swarm. The last chapter of the book focuses on building applications using Microsoft’s new and thinnest server platform – Nano Servers.
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Copyright
Learning Windows Server Containers
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First published: April 2017
Production reference: 1240417
ISBN 978-1-78588-793-2
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Credits
Author
Srikanth Machiraju
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Reviewer
Romeo Mlinar
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Foreword
Containers have become an elegant way to virtualize system level services in the recent past. Coupled with microservices which provide well-bounded, self-contained, application services, containers bring a revolutionary shift to the way solutions are built and deployed on computer infrastructure. Docker has been a favorite way to build containers and container clusters on open source. The ability to pack hundreds or even thousands of these containers into a physical machine provides a great way to deploy services in an optimal and scalable fashion. The ability to use different operating systems in each of the containers (such as, Linux, Windows) along with any needed functionality packed together is a convenience that contributes to building modular systems. Microsoft Windows and Azure cloud platforms have matured over time and plays a critical role in building systems addressing the needs of digital transformation currently underway in enterprise IT systems across the world. Whether it is the enterprise application that handles millions (or billions) of mobile users or one that handles zillions of IoT sensors (connected cars, refrigerators, or whatever you have), it can now be built using Windows as a platform using the containers model and hosted on Azure cloud to provide the necessary scale.
Deployment and frequent releases is another area which has been revolutionized by container technology. DevOps, the practice that bring together development, deployment, and operations into a seamless continuum by making infrastructure as code a reality, is a part of the agile way of building solutions today. By using the concept of containers, enterprise IT teams can effortlessly and efficiently deploy solutions to immutable infrastructure.
This book deals with all the above aspects and is a timely addition to the windows and Azure developer's toolkit to understand windows containers and their usage in building different types of systems. The integration of DevOps into the subject brings a well thought out addition that helps in implementing cutting edge application development practices.
The author is a well-seasoned developer and architect, who has significant experience building modern enterprise solutions for large customers and his practical approach in dealing with this complex subject shines through in every page of this book. Bringing his consulting background and enormous technical prowess to the task, he has detailed out approach to application development with windows containers which will help developers, architects and operation teams in building modern cloud based enterprise scale applications.
Starting with an introduction to containers and microservices, the author takes a developer on a profound journey that covers from building a simple Hello World container to advanced practical usage, such as building complex enterprise applications using SQL Server, Redis Cache, storage volumes, VSTS for continuous build and deployment, resource management, and insights.
Ritesh Modi
Senior Technology Evangelist
Microsoft India
About the Author
Srikanth Machiraju is an ardent techie, DevOps practitioner, and developer consultant on Microsoft Azure and .NET technologies. He works for Microsoft Global Services, Modern Apps team, Hyderabad India. Over the past 9 years he has worked as a lead consultant for design and development of cloud-based application, migrating legacy applications to cloud, corporate trainer on Azure technologies, and speaker at various user group meetings on Microsoft Technologies. He loves to teach and evangelize best practices and patterns in application development. He continues to explore building modern, smart, and cloud-born applications with more reachability and integration using Azure, IoT devices, Artificial Intelligence, deep learning, parallelism, and enterprise level security. When away from work he loves to cook for his family, explore and review new food joints, watch movies, swim, and play Xbox.
He is also working on another artwork called Developing Bots using Microsoft Bot Framework which is due for release by end of 2017. The book focuses on building smart and intelligent bots using Microsoft Bot framework and Azure Cognitive Services.
About the Reviewer
Romeo Mlinar has been working as Microsoft Senior System Engineer. Professionally connected with computer technology for more than a decade. Passionately devoted with Microsoft products and technology, for instance, system center, planning and design of Active Directory, as well as Windows Server services, devoting special attention to virtualization (Hyper-V), which is his recent preoccupation. He bears large number of Microsoft industrial certificates. Since 2012, he is Microsoft's Most Valuable Professional (MVP) for Cloud and Datacenter Management. He is a regular speaker at various IT conferences in the region and abroad. Also, he is an IT Pro and Edu IT Pro User Group lead in Zagreb, Croatia. He spends his free time with people from the IT world, acquiring new knowledge, eagerly sharing it with others, while at the same time enjoying his life with his family.
He blogs at: http://blog.mlinar.biz/.
He was also a reviewer on Hyper-V 2016 Best Practices written by Romain Serre and Benedict Berger.
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Table of Contents
Preface
What this book covers
What you need for this book
Who this book is for
Conventions
Reader feedback
Customer support
Downloading the example code
Errata
Piracy
Questions
Exploring Virtualization
Microsoft's history of virtualization
Understanding virtualization levels
Hardware/platform/server virtualization
Storage virtualization
Network virtualization
OS virtualization
Limitations of virtualization
Machine turn up time
Low resource utilization
Operational costs
Application packaging and deployment
Introduction to containerization
A few key implementations of containers
Docker
Docker architecture
Development life cycle
Docker's success stories
The road ahead for Dockers
Introduction to Windows Server Containers
A little background
Windows Server Container versions
Hyper-V Containers
Why another container type?
Containers terminology
Container host
Container OS image
Container images
Container registry
Dockerfile
Benefits of containers
Windows Server Containers on Azure
Comparing containerization and VM virtualization
Cluster management
Docker Swarm
Kubernetes
DC/OS
Tooling support
Visual Studio Tools for Docker
Visual Studio Code
Visual Studio Online
Docker for Windows
Docker Toolbox for Windows
Who else is working with containers?
Turbo
Rocket
Summary
Deploying First Container
Preparing the development environment
Containers on Windows 10
Windows Server Containers on-premise
Windows Server Containers on Azure
Container options on Windows Server 2016 TP5
Create Windows Server 2016 TP5 on Azure
Installing base OS images and verifying installation
Windows Server Containers development
Pulling images from Docker Hub
Preparing a Windows Containers image
Running web application in Docker
Creating a container
Decoding image preparation
FROM
MAINTAINER
LABEL
RUN
COPY
EXPOSE
CMD
Starting and stopping Docker Service
Summary
Working with Container Images
Listing images
Searching images
docker pull
docker run
Detached versus foreground mode
Name
Isolation technology
Overriding Dockerfile image defaults
docker build
Build context
Build Docker image
dockerignore
Docker tags
docker commit
docker exec
docker push
Cleaning up containers or images
Summary
Developing Container Applications
Setting up the development environment
Understanding .NET Core and ASP.NET Core
ASP.NET Core architecture
Hosting ASP.NET applications
Developing an ASP.NET Core application
The Music Store application
Deploying ASP.NET Core application as Windows Server Container
Dockerizing the application
Connecting the dots
Test and run on a developer machine
Hosting ASP.NET Core on IIS in Windows Server Container
Developing ASP.NET 4.5 applications as Windows Server Containers
Dockerizing ASP.NET 4.5 Web Application
Connecting the dots
Windows Server Container networking
Summary
Deploying Container Applications
Deploy Azure VMs using ARM
Configure VM for remote connectivity
Configuring remote Docker host
docker.pid
dockerd configuration options
Debug
max-concurrent-downloads
max-concurrent-uploads
Host
Security
Deploying containers remotely
Configuring load balancer
Deploy Hyper-V Containers
Pre-requisites
Steps to run Music Store as a Hyper-V Container
Dangling images
Summary
Storage Volumes
Storage volumes
Docker volumes
Sharing volumes
Music Store—store images using volumes
Deleting volumes
Relational databases and SQL Server container
Music Store—store data using SQL Server container
Summary
Redis Cache Containers
Creating Redis Cache container
Creating Redis image and container
Operating Redis Cache containers
Redis Desktop Manager
Publishing Redis container
Persistent Redis containers
Master-slave configuration
Integrating Redis containers with Music Store
Summary
Container Network
Introduction to Windows networking
Windows Containers--network management stack
Configuring container networks
Static port mappings
Disconnecting containers from network
Limitations of WinNAT network implementation
Networking modes
Transparent
L2 bridge or L2 tunnel
Multiple container networks
Container network routing
Single node
Multinode
Multi-subnet deployment of Music Store
Managing Docker networks using Windows PowerShell for Docker
Summary
Continuous Integration and Delivery
Introduction to Visual Studio Team Services
Continuous integration
Signing up for a VSTS account
Uploading Music Store to VSTS
Configuring automated builds
Why do we need a custom build agent?
Custom build agent
Queuing build
Continuous delivery
Configuring service principal name
Configure staging environment
Configure the production environment
Testing CI/CD
Summary
Manage Resource Allocation and REST API
Container resource allocation
CPU resource allocation
Memory allocation
Network allocation
Insights and telemetry
Application Insights
Operations Management Site
Optimizing Dockerfiles
Optimizing image size
Optimize build speed
Ordering instructions
Docker REST API
List containers
Create container
Start/stop container
Removing a container
Docker .NET SDK
List containers
Creating a container
Starting a container
Stopping a container
Removing a container
Downloading an image
Summary
Composite Containers and Clustering
Orchestrating multi-container deployment using docker-compose
A docker-compose file reference
Build options
Naming containers
Dependencies
Named volumes
Docker CLI options
Start/stop services
Building images
Creating containers
Executing commands
Killing commands
Pause or unpause
Scale
Cluster management
Docker Swarm architecture
Setting up a swarm cluster
Generate SSH key
Create swarm cluster on Azure Container Service
Docker Swarm features
Summary
Nano Server
A brief introduction to Nano Server
Benefits of running workloads on Nano Server
Live migrations
Zero footprint
Package management
Reboots
Provisioning time
Server management
PowerShell core
Provisioning Nano Server on Azure
Provisioning Nano Server on Windows 10
Package management
Deploy .NET Core applications on Nano Server
Configuration management using PowerShell DSC
Nano containers
Summary
Preface
Containers is the next breakthrough in building modern and cloud based applications, comparing it with its predecessors like VM virtualization one would realize that containerization is the fastest, most resource-efficient, scalable, and secure way of building application hosting environments we know so far. Learning Windows Server Containers take you through a long and profound journey of building containerized ASP.NET applications on latest windows server platforms using Docker command line and Docker REST API. The book shows you how to build and ship containers from one environment to other with less hassle during the continuous integration and delivery process. You will learn to build containerized applications using scalable storage containers, cache containers with isolation levels like in VMs. The book helps you build an ecosystem of container hosts, manage composite container deployments, and resource governance.
What this book covers
Chapter 1, Exploring Virtualization, teaches you different virtualization levels, challenges with each type of virtualization, containers as a virtualization platform, and benefits of running containerized applications, tooling support, other container platforms available in market today.
Chapter 2, Deploying First Container, teaches you to set up development environment, understand the Docker terminology, installing images from Docker Hub, create custom windows container images using Docker CLI and authoring Dockerfile.
Chapter 3, Working with Container Images, will introduce you to common container management tasks such as listing the containers, start/stop, cleaning up unused containers or images using Docker CLI on Windows Server environment.
Chapter 4, Developing Container Applications, teaches you to create and deploy ASP.NET Core Web applications using Visual Studio 2015, .NET Core, and C# to Windows Server 2016 Core as Windows Container using PowerShell and Docker CLI.
Chapter 5, Deploying Container Applications, teaches you to create Windows Server Container environment on Azure using Azure Resource Manager templates and Azure PowerShell, configure remote management for container hosts, deploy container applications remotely as Windows Containers and Hyper-V containers, configuring software load balancer and so on.
Chapter 6, Storage Volumes, talks about building file based storage based containers using Docker volumes and relational database containers using Microsoft SQL Server.
Chapter 7, Redis Cache Containers, teaches you to create persistent Redis Cache containers using Redis and storage volumes.
Chapter 8, Container Network, introduces you to Windows Container networks, different networking modes, building custom container networks using different networking modes and deploying containers on custom networks.
Chapter 9, Continuous Integration and Delivery, teaches you to build continuous integration and deployment pipelines for container applications using Visual Studio Team Services (TFS Online) on Azure, Docker Hub, and Git. You will learn to create a create a custom build server for building, packaging and releasing containers to windows container hosts.
Chapter 10, Manage Resource Allocation and REST API, teaches you to manage container resource utilization, create and manage containers using Docker REST API via Postman and C#, image optimization strategies and monitoring options available for containers and container hosts.
Chapter 11, Composite Containers and Clustering, teaches you to orchestrate multiple container deployments using Docker Compose, set up scaling for multicontainer environments and authoring DockerCompose service definition. Also, you will learn the concepts of cluster management using Docker Swarm and Azure Container Service.
Chapter 12, Nano Server, serves as an introduction to Windows Nano Server, building custom Nano Server images using PowerShell, deploying containers on Nano Server, working with Nano containers, and configuring Nano Server using PowerShell DSC.
What you need for this book
This book assumes basic knowledge of PowerShell, C#, .NET, ASP.NET 5, cloud computing, and Azure. The book will help your setup development environment on desktop operating system like Windows 10 (with Anniversary update) and deploying container applications on VMs running on-premise and on Azure. To practice building containerized applications on an on-premise environment like Windows 10, the host machine should have Hyper-V feature enabled. The book shows building virtual environments using Windows 10 built-in feature called Hyper-V but you can try any other desktop virtualization software like VMware or virtual box. The book also uses Visual Studio 2015 for application development, if you have hands-on experience working with Visual Studio 2015 it will easy to execute the samples. Following is the basic hardware configuration for running Hyper-V and Visual Studio 2015:
CPU: 1.6 GHz or faster processor, 4 cores
64-bit processor with Second Level Address Translation (SLAT) – (for Hyper-V only)
CPU support for VM Monitor Mode Extension (VT-c on Intel CPU's)
–
(for Hyper-V only)
Minimum of 8 GB RAM
Disk space: 80 GB
Apart from the these, you will also need an Azure subscription for creating container environments on Azure. Microsoft offers a free subscription which can be used for 30 days in-case you do not have a paid subscription. The software requirements for the book are as follows:
Visual Studio 2015 (Community Edition or above)
Windows 10 with Anniversary update
SQL Server Management Studio
Redis Desktop Manager
Postman
Internet connectivity is required to install any packages for application development, download images (ISO files) for windows server 2016 or source code from GitHub repository.
Who this book is for
The primary target audience for this book would be developers who would like to use Windows Server Containers to build portable apps that can run anywhere (laptop, server, and public or private cloud) without little or no changes to the code. Developers will be able to build and ship high-quality applications. As Windows Containers has a broad impact on developers and administrators alike, this book will also help IT professionals or DevOps Engineers prepare infrastructure which is easy to use and maintain. IT professionals will be able to optimize resource utilization by increasing the density of applications per machine. The concepts discussed in this book also help DevOps develop a container mindset, establish practices around publishing developed code as containers from development environment to production easily.
Conventions
In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.
Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "The remove() method finds the first instance of the element (passed an argument) and removes it from the list."
Any command-line input or output is written as follows:
docker search microsoft
New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Click on Test Connection and ensure the connection is successful."
Reader feedback
Feedback from our readers is always welcome. Let us know what you think about this book-what you liked or disliked. Reader feedback is important for us as it helps us develop titles that you will really get the most out of. To send us general feedback, simply e-mail [email protected], and mention the book's title in the subject of your message. If there is a topic that you have expertise in and you are interested in either writing or contributing to a book, see our author guide at www.packtpub.com/authors.
Customer support
Now that you are the proud owner of a Packt book, we have a number of things to help you to get the most from your purchase.
Downloading the example code
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Exploring Virtualization
In this highly competitive and rapidly changing world, for enterprises to be at the leading edge a highly reliable, cost effective, and infinitely scalable IT infrastructure is required. It is very important for enterprises to adapt to changing customer needs, fail fast, learn, and reinvent the wheel. Ever since hardware costs have come down the emphasis has shifted to making the most out of the capital investments made on physical infrastructure or reducing the amount of investments to build or rent new infrastructure. This fundamentally means running more applications/services out of the existing IT landscape.
Virtualized infrastructure solves the preceding problems and it caters to all the IT needs of a modern enterprise. Virtualization provides an abstraction over compute, storage, or networking resources and provides a unified platform for managing the infrastructure. Virtualization facilitates resource optimization, governance over costs, effective utilization of physical space, high availability of line-of-business(LOB) applications, resilient systems, infinite scalability, fault-tolerance environments, and hybrid computing.
The following are a few more features of virtualization:
Virtualization is a software which when installed on your IT infrastructure allows you to run more
virtual machines
(
VMs
) in a single physical server, thereby increasing the density of machines per square feet of area
Virtualization is not just for enabling more computers, it also allows collaborating all storage devices to form a single large virtual storage space, which can be pooled across machines and provisioned on demand
It also provides benefits of hybrid computing by enabling you to run different types of
operating systems
(
OSes
) in parallel, therefore catering to large and varied customers
It centralizes the IT infrastructure and provides one place to manage machines and cost, execute patch updates, or reallocate resources on demand
It reduces carbon footprint, cooling needs, and power consumption
Cloud computing is also an implementation of virtualization. Apart from virtualizing the hardware resources, the cloud also promises to offer rich services such as reliability, self-service, and Internet level scalability on a pay-per-use basis.
Due to reduced costs, today's VMs offered by public or private cloud vendors are highly powerful. But are our applications or services utilizing the server capacity effectively? What percentage of compute and storage are the applications actually using? The answer is very low. Traditional applications are not so resource heavy (except a few batch processing systems, big data systems with heavy scientific calculations, and gaming engines that fully utilize the PC's power). In order to provide high scalability and isolation to the customers we end up running many instances of the application in each VM with 10%-30% utilization. And also it takes substantial amounts of time to procure a machine, configure it for the application and its dependencies, make it ready to use, and of course the number of VMs that you can run on your private data center is limited to the physical space you own. Is it really possible to further optimize resource utilization but still have the same isolation and scalability benefits? Can we get more throughput out of our IT infrastructure than we get today? Can we reduce the amount of preparation work required to onboard an application and make it ready to use? Can we run more services using the same physical infrastructure? Yes, all of this is possible, and containerization is our magic wand.
Containerization is an alternative to VM virtualization from which enterprises can benefit from running multiple software components in a single physical/virtualized machine with the same isolation, security, reliability, and scalability benefits. Apart from effective utilization, containerization also promotes rapid application deployment capabilities with options to package, ship, and deploy software components as independent deployment units called containers.
In this chapter, we are going to learn:
Levels of virtualization
Virtualization challenges
Containerization and its benefits
Windows Server Containers
Hyper-V Containers
Cluster management
Terminology and tooling support
Microsoft's history of virtualization
Microsoft's journey with VM/hardware virtualization began with its first hypervisor called Hyper-V. In the year 2008, Microsoft released Windows Server 2008 and 2008 R2 with Hyper-V role, which is capable of hosting multiple VMs inside a physical machine. Windows Server 2008 was available in different flavors such as Standard, Enterprise, and Datacenter. They all differ in the number of VMs or guest OS that can be hosted for free per server. For example, in Windows Server 2008 Standard edition you can run one guest OS for free and new guest OS licenses have to be purchased for running more VMs. Windows Server 2008 Datacenter edition comes with unlimited Windows guest OS licenses.
At about the same time, Microsoft also shipped another hypervisor called Hyper-V Server 2008 with a limited set of features, such as Windows Server Core, CLI, and Hyper-V role. The basic difference between a server with role and Hyper-V versions is the licensing norms. Microsoft Hyper-V Server is a free edition and it allows you to run a virtualized environment by using existing Windows Server licenses. But of course you would miss the other coolest OS features of full Windows Server as host OS, such as managing the OS using neat and clean GUI. Hyper-V can only be interacted via remote interfacing and a CLI. Hyper-V server is a trimmed down version for catering to the needs of running a virtualized environment.
In the year 2008, Microsoft announced its cloud platform called Windows Azure (now Microsoft Azure), which uses a customized Hyper-V to run a multitenant environment of compute, storage, and network resources using Windows Server machines. Azure provides a rich set of services categorized as Platform as a Service (PaaS) and Infrastructure as a Service (IaaS) using the virtualized infrastructure spread across varied geographical locations.
In August 2012, Windows Server 2012 and 2012 R2 bought significant improvements to the server technology, such as improved multitenancy, private virtual LAN, increased security, multiple live migrations, live storage migrations, less expensive business recovery options, and so on.
Windows Server 2016 marks a significant change in the server OSes from the core. Launched in the second half of the year 2016, Windows Server 2016 has noteworthy benefits, especially for new trends such as containerization and thin OS:
Windows Server 2016 with Windows Server Containers and Hyper-V Containers
: Windows Server 2016 comes with a container role that provides support for containerization. With containers role enabled applications can be easily packaged and deployed as independent containers with a high degree of isolation inside a single VM. Windows Server 2016 comes with two flavors of containers: Windows Server Containers and Hyper-V Containers. Windows Server Containers run directly on Windows Server OS while Hyper-V Containers are the new thin VMs that can run on a Hyper-V. Windows Server 2016 also comes with enhanced Hyper-V capabilities such as nested virtualization.
Windows Server 2016 Nano Server
: Nano Server is a scaled down version of Windows Server OS, which is around 93% smaller than the traditional server. Nano Servers are designed primarily for hosting modern cloud applications called microservices in both private and public clouds.
Other virtualization platforms from Microsoft:
Microsoft also offers a hosted virtualization platform called
Virtual PC
acquired from Connectix in 2003. Hosted virtualization is different from regular hypervisor platforms. Hosted virtualization can run on a 32/64-bit system such as traditional desktop PCs from Windows 7 OS and above, whereas the traditional hypervisors run on special hardware and 64-bit systems only.
A few more virtualization solutions offered by Microsoft are hosted virtualizations called Microsoft Virtual Server 2005 for Windows Server 2003,
Application Virtualization
(
App-V
),
MED-V
for legacy application compatibility, terminal services, and
virtual desktop infrastructure
(
VDI
).
Understanding virtualization levels
Depending on how the underlying infrastructure is abstracted away from the users and the isolation level, various virtualization technologies have evolved. The following sections discuss a few virtualization levels in brief, which eventually lead to containerization.
Hardware/platform/server virtualization
During the pre-virtualization era, a physical machine was considered a singleton entity that could host one operation system and could contain more than one application. Enterprises that run highly critical businesses or multitenant environments need isolation between applications. This limits from using one server for many applications. Hardware virtualization or VM virtualization helped to scale out single physical servers as they host multiple VMs within a single server where each VM can run in complete isolation. Each VM's CPU and memory needs can be configured as per the application's demand.
A discrete software unit called hypervisor or Virtual Machine Manager (VMM) runs on top of virtualized hardware and facilitates server virtualization. Modern cloud platforms, both public and private, are the best examples of hardware virtualization. Each physical server runs an operation system called host OS, which runs multiple VMs each with their own OS called guest OS. The underlying memory and CPU of the host OS is shared across the VMs depending on how the VMs are configured while creating. Server virtualization also enables hybrid computing, which means the guest OS can be of any type, for example, a machine running Windows with Hyper-V role enabled can host VMs running Linux and Windows OSes (for example Windows 10 and Windows 8.1) or even another Windows Server OS. Some examples of server virtualization are VMware, Citrix XenServer, and MS Hyper-V.
In a nutshell, this is what platform virtualization looks like:
Storage virtualization
Storage virtualization refers to pooling of storage resources to provide a single large storage space, which can be managed from a single console. Storage virtualization offers administrative benefits such as managing backups, archiving, on demand storage allocation, and so on.
For example, Windows Azure VMs by default contain two disk drives for storage, but on demand we can add any number of disk drives to the VM within minutes (limited to the VM tier). This allows instant scalability and better utilization since we are only paying for what we use and expand/shrink as per demand.
This is what storage virtualization looks like:
Network virtualization
Network virtualization is the ability to create and manage a logical network of compute, storage, or other network resources. The components of a virtual network can be remotely located in the same or different physical networks across different geographical locations. Virtual networks help us create custom address spaces, logical subnets, custom network security groups for configuring restricted access to a group of nodes, custom IP configuration (few applications demand static IPs or IPs within a specific range), domain defined traffic routing, and so on.
Most of the LOB applications demand logical separation between business components for enhanced security, isolation, and scalability needs. Network virtualization helps build the isolation configuring subnet level security policies, restrict access to logical subnets or nodes using access control list (ACL), and restrict inbound/outbound traffic using custom routing without running a physical network. Public cloud vendors provide network virtualization on pay per use basis for small to medium scale business who cannot afford running a private IT infrastructure. For example, Microsoft Azure allows you to create a virtual network with network security boundaries, secure VPN tunnel to connect to your personal laptops, or on-premise infrastructure, high bandwidth private channels, and so on using pay-per-use pricing. You can run your applications on cloud with tight security among nodes using logical separation without even investing on any network devices.
OS virtualization
The topic of this book is associated with OS virtualization. OS virtualization enables the kernel to be shared across multiple processes inside a single VM with isolation. OS virtualization is also called user-mode or user-space virtualization as it is one level up from the kernel. Individual user-space instances are called containers. The kernel provides all the features for resource management across containers.
This is highly helpful while consolidating a set of services spread across multiple servers into a single server. Few benefits of OS virtualization are high security due to reduced surface of contact for a breach or viruses, better resource management, easy migration of applications or services across hosts, and also instant and dynamic load balancing. OS virtualization does not require any hardware support, so it is easy to implement than other technologies. The most recent implementations of OS virtualization are Linux LXC, Docker, and Windows Server Containers.This is what OS virtualization looks like:
Limitations of virtualization
There are a few limitations with the hardware or VM virtualization, which leads to containerization. Let's look at a few of them.
Machine turn up time
VMs run a fully-fledged OS. Every time a machine needs to be started, restarted, or shut down it involves running the full OS life cycle and booting procedure. A few enterprises employ rigid policies for procuring new IT resources. All of this increases the time required by the team to deliver a VM or to upgrade an existing one because each new request should be fulfilled by a whole set of steps. For example, a machine provisioning involves gathering the requirements, provisioning a new VM, procuring a license and installing OS, allocating storage, network configuration, and setting up redundancy and security policies.
Every time you wish to deploy your application you also have to ensure application specific software requirements such as web servers, database servers, runtimes, and any support software such as plugin drivers are installed on the machine. With teams obliged to deliver at light speed, the current VM virtualization will create more friction and latency.
Low resource utilization
The preceding problem can be partially solved by using the cloud platforms, which offer on-demand resource provisioning, but again public cloud vendors come up with a predefined set of VM configuration and not every application utilizes all allocated compute and memory.
In a common enterprise scenario every small application is deployed in a separate VM for isolation and security benefits. Further for ensuring scalability and availability identical VMs are created and traffic is balanced among them. If the application utilizes only 5-10% of the CPU's capacity, the IT infrastructure is heavily underutilized. Power and cooling needs for such systems are also high, which adds up to the costs. Few applications are used seasonally or by limited set of users, but still the servers have to be up and running. Another important drawback of VMs is that inside a VM OS and supporting services occupy more size than the application itself.
Operational costs
Every IT organization needs an operations team to manage the infrastructure's regular maintenance activities. The team's responsibility is to ensure that activities such as procuring machines, maintaining SOX Compliance, executing regular updates, and security patches are done in a timely manner. The following are a few drawbacks that add up to operational costs due to VM virtualization:
The size of the operations team is proportional to the size of the IT. Large infrastructures require larger teams, therefore more costs to maintain.
Every enterprise is obliged to provide continuous business to its customers for which it has to employ redundant and recovery systems. Recovery systems often take the same amount of resources and configuration as original ones, which means twice the original costs.
Enterprises also have to pay for licenses for each guest OS no matter how little the usage may be.
Application packaging and deployment
VMs are not easily shippable. Every application has to be tested on developer machines, proper instruction sets have to be documented for operations or deployment teams to prepare the machine and deploy the application. No matter how well you document and take precautions in many instances the deployments fail because at the end of the day the application runs on a completely different environment than it is tested on which makes it riskier.
Let us imagine you have successfully installed the application on VM, but still VMs are not easily sharable as application packages due to their extremely large sizes, which makes them misfit for DevOps type work cultures. Imagine your applications need to go through rigorous testing cycles to ensure high quality. Every time you want to deploy and test a developed feature a new environment needs to be created and configured. The application should be deployed on the machine and then the test cases should be executed. In agile teams, release happens quite often, so the turnaround time for the testing phase to begin and results to be out will be quite high because of the machine provisioning and preparation work.
Choosing between VM virtualization or containerization is purely a matter of scope and need. It might not always be feasible to use containers. One advantage, for example, is in VM virtualization the guest OS of the VM and the host OS need not be the same. A Linux VM and a Windows VM can run in parallel on Hyper-V. This is possible because in VM virtualization only the hardware layer is virtualized. Since containers share the kernel OS of the host, a Linux container cannot be shipped to a Windows machine. Having said that, the future holds good things for both containers and VMs in both private and public clouds. There might be cases where an enterprise opts to use a hybrid model depending on scope and need.
Introduction to containerization
Containerization is an ability to build and package applications as shippable containers. Containers run in isolation in a user-mode using a shared kernel. A kernel is the heart of the operating system which accepts the user inputs and converts/translates them as processing instructions for CPU. In a shared kernel mode containers do the same as what VMs do to physical machines. They isolate the applications from the underlying OS needs. Let's see a few key implementations of this technology.
A few key implementations of containers
Some of the key implementations of containers are as follows:
The word
container
has been around since 1982 with the introduction of chroot by Unix, which introduced process isolation.
Chroot
creates a virtual root directory for a process and its child processes, the process running under chroot cannot access anything outside the environment. Such modified environments are also called
chroot jails
.
In 2000, a new isolation mechanism for FreeBSD (a free Unix like OS) was introduced by R&D Associates, Inc.'s owner, Derrick T. Woolworth, it was named jails. Jails are isolated virtual instances of FreeBSD under a single kernel. Each jail has its own files, processes, users, and super accounts. Each jail is sealed from other jails.
Solaris introduced its OS virtualization platform called
zones
in the year 2004 with Solaris 10. One or more applications can run within a zone in isolation. Inter-zone communication was also possible using network APIs.
In 2006, Google launched
process containers
, a technology designed for limiting, accounting, and isolating resource usage. It was later renamed to
control groups
(
cgroups
) and merged into the Linux kernel 2.6.24.
In 2008, Linux launched its first out-of-the-box implementation of containers called
Linux containers
(
LXC
) a derivative of OpenVZ (OpenVZ developed an extension to Linux with the same features earlier). It was implemented using cgroups and
namespaces
. The cgroups allow management and prioritization for CPU, memory, block I/O, and network. Namespaces provided isolation.
Docker
Solomon Hykes, CTO of dotCloud a PaaS (Platform as a Service) company, launched Docker in the year 2013, which reintroduced containerization. Before Docker, containers were just isolated processes and application portability as containers across discrete environments was never guaranteed. Docker introduced application packaging and shipping with containers. Docker isolated applications from infrastructure, which allowed developers to write and test the applications on traditional desktop OS and then easily package and ship it to production servers with less trouble.
Docker architecture
Docker uses client-server architecture. The Docker daemon
