Difference between Kubernetes and Docker

In software development, the main code for the software product goes through several tests before it is finalised. Developers execute the code in different environments. This can be from a developer’s system to the testing environment or from a physical system to a virtual machine. But developers may face problems as the software environment may not be the same at all times.

Using containers can solve all these problems. They have an entire runtime environment within them for the code to run. The application, dependencies, configuration files and libraries are all here. All these files are bundled in a package. There may be some differences in the architecture of different systems. But, it will not be a problem.

Container orchestration is a method that manages and automates the containers. This article will focus on two popular tools of container orchestration – Kubernetes and Docker.

Docker vs Kubernetes

Basis of comparison	Docker	Kubernetes
Cluster setup	Setting up the cluster is a complicated process. But the cluster strength is more	Preparing the cluster is a simple process. But the cluster strength is less
GUI	There is no GUI and you need to perform all operations on the Command Line	It has a GUI based dashboard where you perform all operations
Load balancing	Docker does it automatically	You have to configure the load balancing settings manually
Node support	Supports more than 2000 nodes	Supports not more than 5000 nodes
Tolerance	High fault tolerance	Low fault tolerance
Optimization	This is optimized for working with a single large cluster	This is optimized for working with several clusters
Installation	Quick and easy	Complex and time-consuming
Monitoring and logging	You need to use third-party tools such as ELK	This has in-built tools for monitoring and logging
Automatic scaling	No auto-scaling	Auto-scaling is allowed
Cloud service providers	Works only with Azure	Works with Azure, AWS (Amazon Web Services) and Google Cloud

What is Kubernetes?

Kubernetes is a popular container orchestration system. It is open source in nature. The software was developed by software engineers at Google. This is useful for running containerised applications. These will run on different physical, cloud and virtual environments.

In a production environment, you can use containers for bundling applications. But in case a bundle does not work or shuts down, there may be a problem. Kubernetes helps to manage the orchestration process while handling these containers.

Features of Kubernetes

The different features of Kubernetes are as follows:

Load balancing

Kubernetes is useful for load balancing and handling containers. There may be a case where the traffic to a particular container is high. Kubernetes will balance the load by distributing network traffic. This also helps in easing the deployment process.

Rollbacks and rollouts

You can use Kubernetes to provide the required state to the containers that are deployed. As per a controlled rate, you can alter the actual state of a container as per your desired state. For deployment, you can create a new container. You can embed the resources from an existing container.

Configuration management and protection

Kubernetes can manage Sensitive data such as passwords, ssh keys and OAuth tokens. You do not need to rebuild the container images for updating configuration information and secrets.

Recovery

If a container fails or shuts down, Kubernetes restarts it and replaces it too. Some containers may be non-responsive to the user-defined health checks. Kubernetes kills these containers. These issues are not exposed to clients.

Basic Components of Kubernetes

The primary components of Kubernetes are as follows:

• Cluster – This is a collection of servers. They help you to combine the resources that are available. These will include the CPU, RAM and the hard disk.
• Master – This is a collection of components. They comprise the control panel of Kubernetes. You can use these components for cluster operations. These include responding to different cluster events and scheduling them. The master controls and manages all the nodes.
• Node – A single server or host that can run on a virtual machine or physical machine is a node. This node must run kube-proxy, minikube, and kubele. The Master controls all these.
• Namespace – The logical cluster is also called Namespace. You can use this for dividing a cluster or for scoping access.

Pros and Cons of Kubernetes

Let us look at the advantages of using Kubernetes:

• It is one of the best solutions for container orchestration. So, it has a very active community of users, developers, engineers and cloud providers. Therefore, if you are facing a problem, you are likely to find the solution online
• It is portable and you can execute it on all types of environments. It will run on dedicated virtual machines or public cloud environments. This makes developing a multi-cloud strategy implementable and flexible
• It is scalable and allows horizontal scalability. So by this, you can add or remove new servers. It also offers auto-scaling, manual scaling and a replication controller. Replication controller maintains the containers in the cluster
• It has a variety of storage options such as public clouds and on-premises SANS
• Deployed applications are immutable that enhances the security

The disadvantages of Kubernetes are as follows:

• The configuration and installation process is very complicated
• The horizontal scaling up and manual cluster deployment processes are complex
• It is not compatible with the Docker CLI (Command Line Interface) and Compose tools
• The Kubernetes dashboard is not user-friendly and effective

What is Docker?

Docker is a platform that you can use for containerization of your applications. This makes the life of the developers easy. They are able to develop, package and execute applications using these containers. The containers allow developers to combine all the necessities of an application. These will include different dependencies and libraries. It can be then transferred over to a new environment for execution.

Docker is like a virtual machine. But it does not create a new virtual operating system as in a virtual machine. Instead, Docker uses the same LINUX kernel for running the applications. Some components may not be available on the host computer. You only need to ship them within the container. Thus, the application bundle’s size reduces and it is compatible.

Components of Docker

Let us look at some of the main components of Docker:

Docker engine

The engine is the primary client-server technology. Developers and use this for developing and executing containers for applications. The engine consists of a daemon, a Docker CLI and a REST API. This engine creates a server-side daemon process. The engine hosts containers, storage volumes and images.

Images

These contain the main source code for the containers. You can use any existing image to build your own. These images might have pre-installed software.

Docker client

This also called a CLI (Command Line Interface), which lets you communicate with Docker. You can use it to connect with a remote host or a daemon. The client may be within the same host.

Docker host

This is the environment for running applications.

Registries

The Docker registries store the images you build. Private and public registries are available for use.

Pros and Cons of Docker

The advantages of Docker are as follows:

• It allows you to track and monitor your container versions. You can identify discrepancies also
• The initial set up is simple and can integrate with existing tools of Docker
• Docker makes a container for every process and does not need to start the operating system. It can help to enhance the deployment process
• Containers isolate applications running within them. You will have control over traffic management. So the applications are secure
• Making configurations in the code and running them is a hassle-free process
• The software has great documentation to support users

The disadvantages of Docker are:

• Important features such as copying files from host to a container, self-inspection and registration are not available
• Deploying server applications along with a graphical user interface is tricky
• You cannot reschedule the inactive nodes automatically
• You need to do cluster deployment manually. The process is complex
• If a container shuts down, it loses all data unless you have stored it elsewhere
• The automatic horizontal scaling process is complex

Similarities Between Kubernetes and Docker

There are certain commonalities between Kubernetes and Docker:

• They are both open-source projects and have strong community support
• Both software use YAML files for the specification of deployments. It is also used for application stacks
• Programmers use the GO programming language for writing a lot of the code for these software products
• Both are the most popular names when it comes to container orchestration

Conclusion

The choice of the container orchestration product depends upon your requirements. If you are looking to work with a big cluster and want to monitor it well, choose Kubernetes. It has a simple GUI dashboard and fast response times. So, developing complex applications is better with it. Moreover, the initial set up process is simple and this will help you focus on the important aspects.

But if you are working on a single large cluster and have no problems in handling a CLI, Docker is for you. It has a very well-defined API, so adding extra features to suit your application needs is easier. Docker is best for developing and executing small-scale applications.