Kubernetes Vs Docker

by Aug 15, 2022Article

When you decide to enter the world of containerized applications, two names pop up all the time: Docker and Kubernetes. And then, the doubt arises – which one is better for me? Am I picking the right one? We know you don’t want to waste your precious time building an infrastructure that won’t serve you right, for that reason, we have prepared a comparative article to help you steer your company towards success.

A little bit of history on containers…

The traditional way of offering services was to run applications on physical servers. If you needed to run several applications, they had to either coexist on the same server or run each one on a different physical device. Applications running on the same server couldn’t be isolated, so you’d have to face resource allocation issues from time to time. In addition, any threat–like security attacks would affect all your applications. If you opted for the latter scenario, low usage and costs would add up.

A first attempt to isolate applications, so that they could run on the same physical server, was virtualization. This technology lets you run multiple Virtual Machines (VM) in the same physical device. Each VM is a full machine running all the components, including its own operating system, on top of the virtualized hardware.

Containers are similar to VMs because each one has its own file system, resource sharing, and so on, but they share the same operating system. Therefore, containers are considered lightweight. But the ultimate reason why they have become so popular, especially in cloud-native environments, is that they can be easily moved around.

A container is a running instance of an application, together with its dependencies and configuration, packaged and isolated from other applications running on the same machine. It is thanks to this that developers and operations teams no longer have to go back and forth, as containers don’t depend on the underlying infrastructure. They just need to sit on top of a container runtime environment. The result is that container technology speeds up the development and deployment of applications –including cloud-native apps –incredibly. 

And that’s where Docker and Kubernetes come into play.

What is Docker?

Simply put, Docker is a suite of tools for packaging and executing applications as isolated containers. Some of these tools are:

  • Docker Build: it is used to create a container image that contains your application, dependencies, and configuration.
  • Docker Hub: Docker provides a registry similar to GitHub to share and find container images.
  • Docker Engine: is the container runtime environment. It can run on almost any platform: Mac and Windows PCs, Linux and Windows servers, the cloud, and on-edge devices.
  • Docker Swarm: is a container orchestration tool. It means that it manages a cluster of Docker Engines, usually on different nodes.

In summary, Docker lets developers create container images of their applications, share them or pull images from a registry, and run them on any platform without worrying about dependencies, variables, etc.

What is Kubernetes?

Kubernetes, also known as K8s, is a container orchestration tool. It was initially developed by Google, which then donated the project to CNCF. As we mentioned earlier when we were talking about Docker Swarm, a container orchestration tool manages a cluster of container running nodes, either physical or virtual, in the cloud, or even in hybrid deployment environments. 

Kubernetes manages a cluster of nodes to make them feel like a unified machine. Depending on the requisites and demand of each application, it loads running containers on the best-suited nodes, according to the resource availability on each one.

So which one should I use?

By now, you must be realizing that Docker and Kubernetes aren’t exactly “either/or” technologies. They usually go hand-in-hand in the process of building, delivering, and scaling containerized applications. You can use Docker to create containers for your applications, and then use Kubernetes for managing their production stage. Or, you could use Docker Swarm instead of Kubernetes. Or you could use another containerization tool instead of Docker for your Kubernetes application setup. Or you could even skip container orchestration altogether. When should you use which? Let’s see their pros and cons, and some use cases for each tool so that you can make an informed decision.

Docker features

With that being said, it’s clear to see that you can’t really compare Docker –at least Docker Build– with Kubernetes. So for now, let’s just sum up its main features:

  • A platform for configuring, building, and distributing containers
  • Automated building and deployment of applications – CI

Docker Swarm pros and cons

Let’s have a look at Docker Swarm pros and cons when compared to Kubernetes:

Pros Cons
Easier installation Limited functionality
More lightweight Manual scaling
Easier to use Needs third-party tools for monitoring
Auto load balancing
Integrates Docker CLI

Kubernetes pros and cons

And conversely, these are Kubernetes’ pros and cons when compared to Docker Swarm:

Pros Cons
More powerful Complex installation
Supports auto-scaling More complex with a high learning curve
Built-in monitoring Manual setup of load balancer
Need for a separate CLI tool

When to use each one

Still not sure? Let’s see some use cases for each tool.

You should be using Docker to:

  • disassemble your monolithic application into a series of microservices that could be reused
  • make development and deployment processes more efficient
  • be able to run your application in any environment

You can use Docker Swarm if:

  • you’re only going to run a handful of containers
  • you just want to have a taste of how containerization works for your company
  • you don’t have the time or budget to add a Kubernetes expert to your team

You should use Kubernetes if:

  • you need to be running hundreds or thousands of containers
  • your company is not committed to a single cloud provider
  • you want fine-grained tools for optimizing performance and security

Conclusion

So all in all, Docker and Kubernetes are fundamentally different technologies that work well together for building, delivering, and scaling containerized applications. Each one is useful in some part of the process and they only have minimal overlap. Both are consolidated and stable projects that can make you speed up the development and deployment of your applications. Even more, they’re practically mandatory for cloud-native applications. So, you’d like to use Kubernetes but it seems too complex? We’re here to help! Send us a note and we’ll be happy to help you out. We encourage you to test our playground and see how you can accelerate your cloud-native development. It’s completely free, you simply need to sign up and get started!