The Ultimate Containerization Guide: Docker, Kubernetes and More
Learn how to start with them
When working with software, countless companies have bemoaned the fact that the virtual machines needed to run different parts of it increase their costs considerably.
Recently, many have started using a method called "Containerization," which bundles the application together with all of its related configuration files, libraries, and dependencies.
So why are huge companies, like IBM and Google, getting so excited over this approach?
Simply put, containerization helps companies reduce overhead costs, makes the software more portable, and allows it to be scaled much more easily.
In this article, we'll go over:
- Why container technology is becoming so popular
- A brief history of containerization
- An overview of Docker and Kubernetes
- Who should use containers
- The best container solutions
Containerization vs. Virtualization
Many people try to put containerization against virtualization as if they're completely different approaches, which isn't exactly the best way to look at things. Containerization actually solved all the shortcoming of full virtualization, which is why it’s gained favor from developers across the world.
So, to get started, let's take a look at a few differences between the two technologies:
Once a software component called hypervisor is installed on the server, you can create virtual machines (VMs), which act as separate servers running their own operating systems. This approach usually ends up costing a lot of money since hypervisor and all of the VMs can often take up around 20% of a server's performance.
Containerization is virtualization of the OS kernel. While containers are running isolated processes, they're sharing a common OS, binaries, and libraries. This doesn't use nearly as much space and memory as the traditional VM, which reduces overhead costs considerably.
Containers are much much quicker to create and activate because, unlike VMs, you don't need to install an operating system every time you set one up. Implementation is also much easier since containers are isolated from their surrounding environment, making deploying them in a different environment much simpler.
History of containers: 1970-now
Many of us first started hearing about containers in 2013 when an up-and-coming open-source software called Docker appeared and brought containers into the public sphere. But, the idea of containers is actually much older than that.
Back in the 70s, the operating system UNIX came out with a "chroot" (change root) command, which allowed users to isolate file systems.
20 years later, FreeBSD modified this idea to create a jail command, which let admins divide computer systems into smaller systems (or "jails").
In 2005, Solaris OS created containers that isolated applications so that they could run independently without potentially affecting each other.
One year later, Google engineers created cgroups (control groups) technology, which was later absorbed into the Linux kernel, which then led to the emergence of the "light-weight" virtualization LXC.
But, all of these solutions still needed people with extensive knowledge to manually configure them, so they didn't gain much traction among experts.
Docker was the first to solve this issue in 2013. They used Linux containers, added more functionalities (like portable container images), and made them easier to manage.
And just like that, Docker's containers became almost an overnight success.
Want your own container?
We can help! In Master DC, we offer you virtual servers (VPS) running on KVM platform which allows you to run your own Docker containers.
Docker: #1 in container technology
While there are a few options out there to choose from, Dockers is, without a doubt, the most widespread container technology out there today. Today, 83% of all containers run on Docker. But what is Dockers?
Dockers is a software that allows users to encapsulate apps, libraries, configurational files, binaries and other dependent files into a container so that they can be run in any environment without running into any issues.
But Docker doesn't stop there, the software also manages the container, from creation to the end of its lifecycle.
While it is important to mention that there are other container technologies that exist (LXC, Open-VZ, CoreOS, etc.), they aren't as well known as Docker because they require experts to set them up and maintain them.
Docker Terms You Should Know
(Don’t worry, there won’t be a test afterward.)
Docker Image A compressed, independent piece of software built by Dockerfile. It’s basically a template (application plus required libraries and binaries) needed to build a running Docker container. Images can be used to share containerized applications.
Dockerfile A text file that contains all the commands and instructions needed to build a Docker ImageDocker Run A command that is used to launch Docker containers. Each container is a running instance of an image.
Docker Hub Docker Hub is a cloud-based repository where you can store, manage, download and share container images (both from Docker and from the community).
Docker Engine The core technology that creates and runs Docker containers.
Kubernetes and other orchestrators
Managing containers manually on a single server is tough enough, but what if your containers are spread across hundreds of servers? Impossible, right? Not for an orchestrator like Kubernetes.
An orchestrator is a tool that manages container networks, including the launching, maintaining, and scaling of containerized applications.
Orchestrators have made the lives of many people significantly easier, especially microservices developers. They carry out tasks like making sure that server capacity is being used efficiently, launches services based on needs, stop old container versions and activates new ones, and more.
There are quite a few different container orchestrator tools out there, but, just as with container technologies, there's one that stands out from the pack–Kubernetes, an open-source orchestrator with a wide variety of options that can be customized to fit your needs.
To show you why Kubernetes is the clear winner, let's take a look at some alternatives.
Docker's orchestrator, Docker Swarm, is more simple than Kubernetes, but it was designed primarily for smaller container clusters. While Kubernetes takes a bit more work to deploy, it's a much more comprehensive Docker-approved solution that gives you an easy to manage and resilient application infrastructure.
Mesos, an Apache project, isn't just an orchestration tool, it's essentially a cloud OS that coordinates both containerized and non-containerized components. Many platforms can run simultaneously in Mesos, including Kuberenetes.
Microservices and Containers
Microservices is a way of breaking apps up into smaller modules to make developing and deploying them easier. While this approach still allows these divided portions to communicate with each other, changes in one module don't affect other modules.
While the concept of microservices was developed independently from the idea of containers, container technology enabled people to use microservices technique. For example, the container's orchestrator manages large numbers of containers and makes backups before an update to make rolling back to a previous version easy.
Can containers help me?
Now that we know that using containers can have quite a few benefits, but you might be wondering if this technology can help you.
To make the answer simple: anyone who works with software can benefit from using container technology.
Let's just take a look at a few ways containers can help you:
- Containers make software super portable.
- Since the software is enclosed in a container, it can run on any machine without issue.
- It's more secure. Isolated software won't have a negative impact on other systems.
- Easily scalable software. Whether the number of users is increasing or decreasing, containers allow you to immediately react.
Making Scaling Easy
Since containers are so light-weight, they usually only take a few seconds to start (compared to the minutes it takes to run a VM). Since this process also divides the app into smaller parts, containers also allow us to use server resources much more efficiently. Containers can also scale microservices multiple times instead of just once, making the process much faster.
Transition to containers
While it is possible to encapsulate a giant monolithic application in one container, you won't get all the benefits that containers have to offer. Containers use server's resources most efficiently when apps are divided into smaller parts (especially since microservices might need to be scaled many times, and other portions might only need to be scaled once).
There are a few ways you can break down monolithic applications, but unfortunately, no universal method exists. The more data dependencies there are, the more difficult it is to divide.
Which container tool is best for me?
Since both Docker and Kubernetes are open-source projects, you can start running containers on your own. But, keep in mind that transitioning large projects to containers can be a massive undertaking. If you don't have the time or expertise to do it yourself, we recommend reaching out to an organization to set your solution up for you.
In Master DC, we offer a few types of container setups you can choose from:
- Virtual servers (VPS) with KVM virtualization — allows the user to install Docker and run own their containers
- Managed Kubernetes cluster running on physical servers — ideal for larger projects since the Kuberenetes orchestrator requires at least 2-3 servers to operate
- Managed Kubernetes cluster running completely on the cloud — ideal for smaller projects
- Hybrid managed Kubernetes cluster — orchestrator runs in the cloud, containers run on dedicated physical servers
The future of containers
Everyone knows that containers are going to be influential in the technology of the near future, and now that large players like Google and IBM are placing their bets on container tools, we don't see this going away anytime soon.
In 2019, Turbomic report has shown that 26 % of IT companies have already started to use containerized applications, and that number is expected to double by 2021.
Some companies have started using containers outside of servers. Linux recently launched Flatpak, a container-based software utility for software deployment and package management. With Flatpak, people can use applications that are isolated from the rest of the system, which strengthens security, makes updating easier, and discourages wasting resources collecting unnecessary data.
Team Silverview also went all-in with container technology when they created Fedora, an experimental OS that distributes all software into containers.
Want to make sure your company isn't left behind? At Master DC, we can work with you to determine which container solution best fits your needs, and make the transition as smooth as possible.