What’s all the hoopla about Containers and Docker?

DockerI don’t know about you, but in my circles I hear a growing buzz about Containers, Docker, and how this will revolutionize the way we deploy software. What is this new thing and how will it affect you?

The Short Version

The short version is that container technology will allow you to run more apps on the same amount of hardware (in the cloud or on premise). So, fewer real machines, fewer virtual machines (VMs), lower cost for maintaining and upgrading VMS… much the same that the transition to VMs in the cloud has brought to you, but even better.

Which pain are we solving?

In the old days, each time a business app was to be deployed, you would have to purchase a set of machines to run it on, which could cost quite a bit of money, with hardware, operating systems, software licenses, and maintenance costs. These would tend to be over-dimensioned, to mitigate the risk of any poor performance or becoming obsolete too fast. But in reality, they would mainly be under-utilized. Asides from running the actual business app that provided the value you wanted, each machine also ran an operating system. The operating system granted access to the hardware (memory, disk space, processors).
One machine per app
Well as you know, along came VMs. With a VM, something called a hypervisor sits atop the host operating system, and slices up the access to hardware into a set of guest operating systems. These all shared the same hardware – maybe you would give each app one CPU, 2GB of memory, and 1 TB of disk – so you got more out of your capital expense. Importantly, these apps and their guest operating systems were isolated from each other, each thinking they had their own hardware, and couldn’t bring each other down.
One app per VM
This was a big improvement. Now you could wring a lot more out of the same hardware. Along came a host of VMs ranging from VMWare to Microsoft Hyper-V. And along with these came amazing tools and technology for managing these VMs, especially in the cloud. You could spin up a VM in no time, and pay for usage of resources, scale farms of VM’s elastically to meet peak needs, do your development and testing on temporary cloud VMs, etc.
However, there were still a lot of wasted resources in this picture. Given that what we really care about is running our apps, the large set of duplicated guest operating systems is a problem. Each one comes with a lot of cost: you need operating system licenses, they take up a a good percentage of your hardware resources just to run (memory, CPU, disk), leaving much less resources for your apps.
Containers to the rescue:
One app per container
A Container slices up operating resources in the same way a Hypervisor slices up access to hardware. It gives access to a protected process space (with memory and threads), file system and network stack, where each app is protected from the others, but without the overhead of a whole guest operating system for each. You can now run way more apps on the same hardware, and pay for way less operating systems, never minds the costs of maintaining and upgrading them.

What is Docker?

Just as there were originally different operating systems, different hypervisors, different clouds, there are also different container systems. One of the more popular ones is called Docker.
Docker
Docker originally only supported Linux, so the apps running would also have to be Linux apps. But Microsoft jumped in early, and brought Docker technology to Windows and Azure, so now you can run Docker on Windows as well, and run Windows apps.
You can run the Docker Engine on your local development machine, on your networked servers, in all kinds of data centers, and in the Azure or AWS or other clouds. Recently, a whole lot of effort is going into tooling for Docker, to make it just as easy to deploy your apps to Docker as it is to deploy them to a physical machine or a VM, running anywhere. At that point, why would you want to do anything else? Why pay for an extra OS license for each app? Why have to maintain the OS of a VM for each app? Why waste half of your VM or real resources on OS processes, cutting your performance? It’s a no brainer.
One minor point before I continue… the pictures above look like all the apps and OSes are homogenous, but of course they are not: you can have a Linux and a windows VM on the same hardware. However, the Docker apps are. You run windows workloads on windows Docker hosts, and Linux payloads on Linux Docker hosts.

Containers

So what exactly is a Container?
The analogy comes from the shipping industry. Before the advent of standardized shipping containers, loading cargo on to or off of ships, trucks and trains was mayhem! Cargo came in all kinds of bags, boxes and pallets, and in all kinds of shapes and sizes. But with containers, you can put your stuff in a standard container, and it can be loaded, unloaded, moved around, all over the world, using standardized machines and procedures, whether you are shipping peanuts, cars or art.
containers
The same goes for software containers: you can ship your app to a range of different destinations, from your laptop to Amazon AWS or Azure, to dev, QA or production, in a container, that makes your app behave the same way no matter where it gets shipped!
Container for code

Images

There are tools and processes used to make your app into a container, i.e. to Dockerize it. These tools are very smart about the use of space: since many apps will be sharing many of the same binaries (for instance, 5 web apps or APIs might all need a web server), these common images are actually shared for real, and only need to be deployed once, even when used by tons of containers.
For instance, you might have 2 apps that both need IIS running on .NET. You would layer this as follows, and when deployed, only one copy of the IIS and the .NET nanoserver image would be actually deployed. This saves disk space, and it saves network bandwidth when deploying Containers.
Images
Docker uses a smart layered file system, where the underlying layers are read only, and only the top one is writable. When you try to write to an underlying layer, a copy of it is created in your top layer, but the underlying ones remains unchanged. Since they never change, they can be shared. This was already built in to Linux – Microsoft had to pull a few tricks and do some additional work on Windows to enable these features.
A Container is described by a Dockerfile that explains how to take a base image and add to it what you need to do. For instance, download and install certain Nuget packages, run certain commands or scripts, write certain configuration files. These commands could also be to do with provisioning or configuring different environments, like DEV, QA and PROD. Basically, you take your underlying layers, your specific app code and configuration, combine them in a Dockerfile, and you have the instructions to build your Container. The Container is actually instantiated with Docker commands, locally or remotely, that download the images in your layers, start a new container, assign it operating system resources, and run your commands, usually resulting in some process like a Web Server or a Database Server waiting for input.
Note that in ALL these diagrams above, from the beginning of the article, your app is unchanged. It is the same code, the same binary… nothing needs to be done for it to run in a container.
Now that you see how you can package you software into containers, there are a few more even more powerful concepts coming down the road.

Clustering

Likely in the last few years you have become accustomed to building stateless apps that can be scaled out in a web farm, using maybe AWS and ELB, or Azure App Services. You need some kind of smart load balancer, and you need your apps to be stateless, and for failover to happen automatically. Sometimes (in the context of databases or Redis) you use the concept of a high availability cluster. The concept in Docker is called Swarm.
Swarm
In Swarm, you can deploy your app to a number of nodes, say 10, running on a number of Docker engines. Those engines can be on different machines, or even in different data centers – even some in Azure and some in AWS! If any one of those nodes dies (crashes, or is on a machine that dies, or loses a network connection), the other nodes automatically take over the load, and create a new node to replace the missing one. You do this declaratively: you say you want 10 nodes. You don’t have to micromanage any of the details of the configuration, or the failover itself. Swarm makes sure you will always have the number of nodes running that you specified.
With Swarm, some of the nodes are managers (typically 3 are). These managers communicate with each other and make sure they are alive and well, and that the required number of nodes is running. They also run regular node workloads (containers). So out of 10 nodes, 3 may also be managers.
Managers and workers
This is all accomplished in software, internally inside the Docker Swarm Engine. You don’t need your smart load balancers to know about it at all. Technically you don’t even need a load balancer, Swarm will adjust requests to the right container to balance the workload all by itself. Of course, it helps if you have some piece of software or hardware that maps the same IP across a range of Docker engine hosts, but technically just one mapping is enough, the rest happens internally.

Orchestration

The other concept is Orchestration.
Components
A typical mordern business app is not a monolith, it is a set of discrete parts, possibly each one written in a different language. For instance, we might have a Single Page Application (SPA) written in HTML 5 and Angular, (Web App) calling a REST Web API written in C# using .NET Core and Entity Framework Core, authenticating against a directory service to get a bearer token that is passed to the Web API. The Web API might uses a Redis cache and a MS SQL database.
This kind of architecture is becoming even more prevalent with the advent of things like micro services.
The apps all communicate with one another; typically HTTP over SSL on port 443 between the Web App and the WebAPI and Auth, and maybe port 1433 TCP to the MS SQL database, and port 6379 for Redis. They run in different containers, possibly on the same, but more likely on different machines. However, the web app doesn’t need access to the DB port or Redis, nor does the Auth app need access to the MS SQL DB.
With orchestration, you describe how all these containers fit together, and what their communication needs are. Then, when you go to deploy, all this is automatically configured for you. The lingo for this is Docker Compose:
Compose
Docker Compose and Docker Swarm come together when you describe how your containers fit together, but also how many instances of each you need running. Maybe you want a set of 3 SPA frontends, 2 Web APIs, and one each of Auth, Redis and MS SQL.
Compose and Swarm

Docker Hub and Repos

One last concept to mention here is Docker Hub. Remember I talked about the standard image layers for say IIS or MS SQL or .NET? Well, you can download these from DockerHub at https://hub.docker.com/, just as you would download packages from Nuget. The images are stored in different repositories, some are public (like Microsoft’s) and some are private = yours! You can create your own images and save them to your private enterprise DockerHub repo (just as you can save code to your private GitHub). And for those of you too paranoid for that, there is also a version you can run inside of your corporate firewall. Below you can see the official Repos for Redis, Ubuntu, Mongo DB and more. And of course all these technologies support versioning.
DockerHub
Now I hope you have a basic understanding of what Containers are, and what Docker in particular is. It is evolving extremely fast, is open source, has broad industry and community support, and it is going to save you a lot of money and headaches, while being fully backward compatible with your existing business apps.
So in my opinion it is high time to start learning about it; have your IT people and software teams start reading and learning on line, and try some in house projects using Docker for your development and QA, so you can hit the ground running.

Related Blog Posts

We hope you’ve found this to be helpful and are walking away with some new, useful insights. If you want to learn more, here are a couple of related articles that others also usually find to be interesting:

Our Gear Is Packed and We're Excited to Explore with You

Ready to come with us? 

Together, we can map your company’s tech journey and start down the trails. If you’re set to take the first step, simply fill out the form below. We’ll be in touch – and you’ll have a partner who cares about you and your company. 

We can’t wait to hear from you! 

This field is for validation purposes and should be left unchanged.

Together, we can map your company’s tech journey and start down the trails. If you’re set to take the first step, simply fill out the form below. We’ll be in touch – and you’ll have a partner who cares about you and your company. 

We can’t wait to hear from you! 

Montage Portal

Montage Furniture Services provides furniture protection plans and claims processing services to a wide selection of furniture retailers and consumers.

Project Background

Montage was looking to build a new web portal for both Retailers and Consumers, which would integrate with Dynamics CRM and other legacy systems. The portal needed to be multi tenant and support branding and configuration for different Retailers. Trailhead architected the new Montage Platform, including the Portal and all of it’s back end integrations, did the UI/UX and then delivered the new system, along with enhancements to DevOps and processes.

Logistics

We’ve logged countless miles exploring the tech world. In doing so, we gained the experience that enables us to deliver your unique software and systems architecture needs. Our team of seasoned tech vets can provide you with:

Custom App and Software Development

We collaborate with you throughout the entire process because your customized tech should fit your needs, not just those of other clients.

Cloud and Mobile Applications

The modern world demands versatile technology, and this is exactly what your mobile and cloud-based apps will give you.

User Experience and Interface (UX/UI) Design

We want your end users to have optimal experiences with tech that is highly intuitive and responsive.

DevOps

This combination of Agile software development and IT operations provides you with high-quality software at reduced cost, time, and risk.

Trailhead stepped into a challenging project – building our new web architecture and redeveloping our portals at the same time the business was migrating from a legacy system to our new CRM solution. They were able to not only significantly improve our web development architecture but our development and deployment processes as well as the functionality and performance of our portals. The feedback from customers has been overwhelmingly positive. Trailhead has proven themselves to be a valuable partner.

– BOB DOERKSEN, Vice President of Technology Services
at Montage Furniture Services

Technologies Used

When you hit the trails, it is essential to bring appropriate gear. The same holds true for your digital technology needs. That’s why Trailhead builds custom solutions on trusted platforms like .NET, Angular, React, and Xamarin.

Expertise

We partner with businesses who need intuitive custom software, responsive mobile applications, and advanced cloud technologies. And our extensive experience in the tech field allows us to help you map out the right path for all your digital technology needs.

  • Project Management
  • Architecture
  • Web App Development
  • Cloud Development
  • DevOps
  • Process Improvements
  • Legacy System Integration
  • UI Design
  • Manual QA
  • Back end/API/Database development

We partner with businesses who need intuitive custom software, responsive mobile applications, and advanced cloud technologies. And our extensive experience in the tech field allows us to help you map out the right path for all your digital technology needs.

Our Gear Is Packed and We're Excited to Explore with You

Ready to come with us? 

Together, we can map your company’s tech journey and start down the trails. If you’re set to take the first step, simply fill out the contact form. We’ll be in touch – and you’ll have a partner who cares about you and your company. 

We can’t wait to hear from you! 

This field is for validation purposes and should be left unchanged.

Thank you message.

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.