Do you wonder about the merits of Kubernetes vs. Docker? Let’s get into the details to talk about their differences and how they work together.
Docker is about developing and shipping applications within containers – also known as Docker images – while Kubernetes is high-level orchestration to potentially billions of these containers. They’re different but complementary and work well together in large-scale, complicated deployments.
As we discuss the differences and advantages of each platform you’ll understand the big picture and be able to learn more with in-depth resources to get you both book knowledge and hands-on experience.
What are containers?
To better understand the merits of Kubernetes vs Docker, it’s helpful to take a step back and get comfortable with the concept of containers in application development and deployment.
A container is a unit of software that bundles code and all dependencies together so that the application can run quickly and reliably in any computing environment.
Containers can be described as lightweight virtual machines. Virtual machines require you to virtualize the entire operating system and any software you wish to run. This makes VMs very resource-intensive.
Containers were introduced by the Linux operating system to address this problem. It’s simple: if you already have a Linux OS running on your computer, why not create a new OS for each VM using that OS? You can instead use the core OS (called the kernel) for each VM. So, VMs can only run the software they are required to.
Containers are helping teams of any size to resolve issues such as consistency, scalability, security, and scalability. Containers such as Docker can be used to separate the application and the underlying infrastructure.
What is Docker?
Docker allows you to separate your application and the underlying infrastructure. It bundles up your code with all its dependencies into one self-contained entity which will run on any supported system.
Advantages and disadvantages of Docker
Besides being the most popular platform and the defacto standard for container images, the benefits of Docker are the benefits of containerization:
Advantages of Docker
Docker (i.e. Docker Compose) is portable, scalable, and has increased security from being isolated. This may be a different setup than what you’re used to, which leads us to some of Docker’s cons.
Disadvantages of Docker
It’s true, containerization does have some disadvantages. The naysayers say that they’re not as slow as running on bare metal, the ecosystem is general is a little all over the place and fractured, there are challenges with persistent storage since the container can be moved / is modular, and some applications (especially monolithic ones) would perform badly with containers.
What is Kubernetes
Kubernetes is the current standard in container orchestration systems.
Kubernetes makes it easy to manage and deploy containers at a large scale. Google developed it based on years of experience with containers in production. Kubernetes gives you a toolbox that automates scaling and operating containerized apps in production.
Advantages and disadvantages of Kubernetes
The advantages of Kubernetes are everything we’ve reviewed above, including:
- load balancing
- automatic packaging
- self healing systems
- powerful for CI/CD methodologies
- sophisticated orchestration of complex deployments
Kubernetes does have some disadvantages, which are the flipside of all the pros listed above:
- can be too much of a solution / overkill for all but the larger deployments
- can be slow to implement and have a learning curve
- its sophistication brings added complexity to a project
What’s the difference between Kubernetes vs. Docker?
As referenced at the start of this post, the difference between Kubernetes and Docker is pretty big. When people mention Docker, they’re usually referring to Docker Compose which is used for creating individual containerized applications. Docker Compose has become the standard so people just throw around the term “Docker” for shorthand.
Kubernetes is an orchestration system where you can control all your container resources from one single management plane.It was originally created by Google to monitor and control large (i.e. billions) of containers and is now open source.
Kubernetes vs. Docker Compose
When people ask “Kubernetes vs Docker” they really mean Docker Compose, the core Docker product which allows you to create containerized applications. When thinking about your options, a good question for yourself can be, “Why not both?” With the two technologies, you’ll be able to isolate applications as containerized systems and orchestrate huge numbers of them in a safe and dependable way.
Kubernetes vs. Docker Swarm
Docker Swarm is the container orchestration system from Docker, so comparing it to Kubernetes is much more applicable than saying “Kubernetes vs Docker Compose”. Docker Swarm is a more lightweight and simpler orchestration system than Kubernetes, but it lacks strengths that Kubernetes had in automation and self-healing – features that can be important to huge deployments.
Kubernetes vs Docker certifications
Kubernetes has more certifications than Docker, but since the two technologies are different it’s still useful to be familiar with the certs from both. Below are resources to get you familiar with Kubernetes and Docker certs.
This learning path covers all the general domains of the CKA certification exam. This series of courses, labs, and exams is for cluster administrators who already have familiarity with Docker.
This learning path covers all domains of the CKAD exam. This is intended for Kubernetes application developers, but is also useful for anyone who wants to learn how to work with Kubernetes.
CKS certification demonstrates that the person has command over securing the Kubernetes technology stack. CKA certification is required before you sit for the CKS.
The KCNA is a foundational-level certification that helps learners progress to the more advanced Kubernetes certs: CKA, CKAD, and CKS.
This learning path covers six DOcker domains, allowing you to become proficient in Docker orchestration, security, etc. Ideally, Docker recommends 6-12 months of experience with its technology before you start a certification course.
Resources: Learn about Kubernetes, Docker, and microservices
This Learning Path will show you how to engineer and operate containers in production-like environments. The Learning Path will begin by introducing you to Docker containers and then move on to concepts such Dockerfiles. You’ll learn the entire process for container development and deployment. This Learning Path ends with you building, deploying and testing your Kubernetes cloud-native containerised application.
This learning path is for anyone who wants to manage containers at scale. By the time you’re done, you’ll be able to use Kubernetes to manage containers, as well as deploy a stateless and stateful application.
Learn all about Docker from individual containers to continuous deployment of an application in AWS.
With this learning path you’ll get a taste of engineering and operating containers in production-like environments, culminating with building, deploying, and testing your own Kubernetes cluster.
Learn the basics of designing, building and deploying production-grade microservices using Python, Flask, and Docker containers.
Can I use Kubernetes without Docker?
Technically, yes you can use Kubernetes without Docker as long as you have some other kind of container runtime. A couple of options are containerd and Podman, though Docker is by far the most popular container platform.
Is Kubernetes free?
Yes, it’s free if you use the completely open source version available on its GitHub repository. A lot of users end up preferring to use the Kubernetes offering that is bundled with other services, libraries, platforms, etc. on the big cloud offerings. Some even have more fully-managed offerings that are helpful but more expensive.
Should I learn Docker or Kubernetes first?
Yes, it’s a good idea to start with the smaller part of the system: the container (Docker Compose) and then move up to the orchestration system (Kubernetes). But if you’re passionate and curious, by all means, jump into both at the same time to see where your learning takes you.
Are containers outdated?
Not yet. They’re still valuable to microservices-based architectures even though they’ve basically been around as long as virtual machines. Some people thought they would be replaced by serverless or no-code solutions but those tend to solve different solutions at different scales.