Kubernetes VS Docker


What is the difference between Kubernetes(K8s) and Docker? Are they generally doing the same thing, or they are two different services? We will start the comparison by a brief description of what each of them does. The latter is a containerization platform and runtime. On the other hand, K8s is a platform to run and manage containers from several container runtimes. It supports a large variety of container runtimes.

This comparison may not make sense for some people. It is like comparing a driver with their car. We cannot say which one is better than the other and we cannot talk about their pros and cons. Because such comparison wouldn’t make sense. But what if someone who is not familiar (e.g. an alien) with the two asks us to compare the two for them? Now you should clarify their differences and say why they are two different things and why they are not comparable with the mentioned method. With the given example, now it may make more sense to put Kubernetes vs Docker.

Docker has provided the first container platform with a computing model based on micro-services. Like other containers, this one is not dependent on any operating system. Instead, it works with scalable microservices that allows teams to declaratively package an application, it’s dependencies, and configurations together as a single container image.

But like everything – specially in tech – applications grew in complexity and demanded distribution of their container across multiple servers. Thus made various challenges such as coordination and scheduling of multiple containers, enabling communication between them, scaling individual instances of the container, and maybe more. The solution then came up under the name of “Container Orchestration”. One of such services is Kubernetes. The free and open-source dominator of the market, and the brain of a lot of containerized applications. To add more details into the description, let’s check the definition of each of them individually in the context.

What is Docker?

As said, and in short, it is a containerization platform and runtime that lets developers build, deploy, and run containers with a fluid workflow. A developer can create a container without using this specific platform just as well. But using it makes doing so much easier and faster. Unlike Kubernetes, it is a commercial application and the source code is not open. The architecture used by Docker is a client-server architecture with simple commands and automation through a single API.

This platform provides a toolkit that can be used to package your applications into immutable container images. It does that by writing a Dockerfile and then running the needed commands to build the image using its own server. After making the images, the developer can then deploy and run them on any platform that supports containers, such as K8s, Swarm, HashiCorp Nomad, or Mesos.

The platforms mentioned in the previous paragraph are the ones that can help users/developers manage their containers better, faster, and easier.



What is Kubernetes?

Kuberenetes is the most popular platform for container orchestration. It is an open-source runtime system that can be used across a cluster of networked resources. It is not necessary to use Docker when using K8s as it can be used with any compatible containerized application.

Originally developed by Google, it is now continuing its development thanks to Cloud Native Computing Foundation (or CNCF for short). Google needed a new way to run billions of containers every week, thus they came up with solution that we now as Kubernetes nowadays after they made it open-source in 2014. The main goal of this widely used platform as said by google is: “to make it easy to deploy and manage complex distributed systems, while still benefiting from improved utilization that containers enable.”

With this container orchestration platform, one can bundle a set of containers into a group called a container set, then let it manage them. K8s manages the container set on the same machine to reduce network overhead and increase the efficiency of the utilization of resources.

This platform is especially useful for DevOps teams. As it offers service discovery, load balancing per cluster, automatic rollbacks and rollouts, self-healing of failed containers, and configuration management. Besides, one can say it is a critical tool to build a robust DevOps CI/CD pipeline.

Why Docker?

Development teams are usually changing in a constant manner, a developer comes, another one goes. Environments can be changing as well; What if you want to run your app in two different environments or even more? Even the software itself! It constantly grows with new features and improvements. And finally, the users of your software. So from the deep in the water to the very surface of it – the users – everything needs to be flexible, scalable, and compatible. What if one says there is a single solution for all of these challenges?

Constant changes in the development team

It takes time for a new comer developer to get familiar with project and the workflow. They also have to set up their local environment for the project before they can start coding. Setting up a local server and a database, installing third-party libraries, and more tasks depending on the project, are time consuming tasks that can take from a few hours to many days, depending on the scale of the project. Thanks to Docker, most of these processes or possibly even all of them can be automated. With this platform, the frustration of early days of entering a new project will be replaced by productivity from the very early days.

Running your software across multiple environments

Your software is probably running at least, on two different environments. One is the developers’ computers, and the other one is a server. Even in such a simple case, inconsistent behavior of the app between the two environments can be noticed easily. Something may work on a developer’s machine, but not on the server. And the issues will increase linearly with the number of various environments it will run on. Imagine a developer using a distribution of GNU/Linux, another one using Windows 11, and then there is a test server and a production server. The environment variation grows easier than one may anticipate. With Docker, the app can run isolated from the environment, in its own container, not caring what is going on in the outside world. Just working in a consistent, predictable way regardless of the environment.

Expanding and improving your application

The development team requires to add new libraries, services, and other dependencies to the software almost every day. Thus making your software more and more complex in a daily manner. Making it harder to keep track of all its parts that are required for it to run. All these changes have to be communicated to other developers and should be documented. But Docker removes such extra processes by making all the dependencies embedded with the software by integrating them in the container.

There are a lot more benefits from using this platform, which deserves a separate article and cannot be discussed here as a whole. Some reasons to avoid as well, of course. But continuing on,

Why Kubernetes?

While containerization of your application (either manually, or using a containerization platform) can make it more scalable, more flexible, and easier to develop across multiple environments, there remains some other challenges that the development team should struggle with and overcome. Challenges such as management and scaling of the containerized applications (microservices). Kubernetes, as an automation /- orchestration platform for containers, can be the answer to most of the remaining challenges.

Automating Operations

Kubernetes has a powerful API and CLI tool, called KubeCTL. It handles a bulk of heavy lifting that goes into container management by letting the development team to automate their operations. The controller pattern makes sure that applications and containers run exactly as specified.

Abstracting Infrastructure

K8s takes responsibility for management of the resources available to it. This lets developers focus more on designing, programming, and writing codes for the application rather than spending time on the underlying compute, networking, and storage infrastructure.

Monitoring the Health of the Service

Kubernetes not only takes care of the resource management, but also monitors and manages the running environment. By comparing the monitored data against the desired state, it then performs automated health checks. After that, if it finds a problem, it will restart the container that have failed or stopped working. This platform makes services available only when they are running and are ready.

Kubernetes VS Docker: Which one is right for you?

Docker also has its own orchestration system called Swarm. The problem is that by using this system, you are limited to one specific containerization platform while Kubernetes doesn’t have this limitation. So considering that Docker has its own exclusive alternative to K8s, which one is right for you?

Docker is simpler to setup and configure compared to Kubernetes. But that is only important when you are building your own infrastructure as a third-party provider such Green Plus will do these for you already. Aside from that, it offers the same benefits as K8s, such as deploying your application through declarative YAML files, automatically scaling services to your desired state, load balancing across containers within a cluster, and security / access control across your services. There are various minor differences in how the two orchestration systems do these tasks and some different special features for each.

On the other hand, Kubernetes takes more time and effort to setup in the beginning but it worth the greater flexibility and features. In addition to the wider support thanks to its open source community. K8s supports multiple deployment strategies by default, is able to manage a network’s ingress, and also provides observability for the containers out of the box. All major cloud vendors such as IBM, and most of the rest of service providers such as Green Plus, offer managed Kubernetes services. This can be a huge skip forward in your timeline and lets you utilize the orchestration platform without wasting time on setting it up and configuring it.

Unless you have to make your infrastructure by yourself and you are sure that Docker is the only containerization platform you need in the long term, there is no reason to hold yourself back by using Swarm.

You can use Green Plus’s cloud servers with the integrated Kubernetes feature that lets you use the server with Kubernetes already enabled and ready to use with near zero additional effort.

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