Docker and Kubernetes are two of the leading tools used in the cloud computing industry. While Docker is a computer application that uses the concept of containerization, and Kubernetes is a container orchestration system.
As a rule, Docker and Kubernetes are used in conjunction with each other. However, comparing Kubernetes and Docker is an extremely popular topic in the cloud computing community.
Before comparing the two most important cloud computing technologies, let’s first briefly describe each of them.
Kubernetes
First released in June 2014, Kubernetes was originally developed by Google. The Cloud Native Computing Foundation is responsible for further development and maintenance of the open source container orchestration system.
According to the official website, Kubernetes is “an open source system for automating the deployment, scaling, and management of containerized applications.”
Using containerization technology, Kubernetes allows you to run containers on multiple computing nodes, which can be simple servers or virtual machines. Before using Kubernetes, you need to double-check a few things. One of them is to ensure that all participating computing nodes are securely connected to each other.
Docker
Developed by Docker, Inc., Docker was first released in March 2013. It is a computer program capable of performing operating system-level virtualization, commonly known as container packaging.
Docker can be viewed in two different ways. At first glance, Docker containers are really lightweight virtual machines, and from a second point of view, Docker is a platform for packaging and delivering software.
The latter aspect is primarily responsible for the huge popularity of Docker containerization technology and its widespread adoption in the cloud computing industry.
Is it possible to compare Docker and Kubernetes?
Comparing Docker to Kubernetes is like comparing the Sun to the Moon. Of course, both celestial bodies, but the comparison between them does not sound right! This is because, although both are shining, one is a star and the other is a natural satellite.
While Docker can work without Kubernetes, and Kubernetes can function fully without Docker, using both in collaboration improves each other’s functionality. Docker can be installed on your computer to run container applications. The containerization approach means running applications on the operating system in such a way that they are isolated from the rest of the system. The app will feel like it has its own dedicated OS.
Multiple applications can run on the same OS, as if each of them had its own instance of the operating system. Each application is located inside a container. Docker allows you to create, manage, and run containers on a single operating system.
Now that you have Docker installed on multiple hosts, i.e. operating systems, you can use Kubernetes. In this case, we call these hosts nodes or Docker nodes, which can be open source servers or virtual machines. The beauty of using Kubernetes with Docker is that It helps automate container load balancing, networking, resource allocation, scaling, and security across all Docker hosts using a separate dashboard or command-line interface.
Improving application scalability and infrastructure reliability are two of the best reasons to choose multiple nodes. A collection of nodes managed by a single Kubernetes instance is called a Kubernetes cluster.
Docker VS Kubernetes
Docker Swarm, which you can read about setting up here , is an open source container orchestration platform. This is a native clustering mechanism for Docker, and therefore it uses the same command line as Docker. Below are various important differences between Swarm and Kubernetes.
- APPLICATION DEPLOYMENT
The application is deployed in Kubernetes using a combination of modules and services (or microservices). In Docker Swarm, the application is deployed simply as microservices or services in a Swarm cluster.
Docker Swarm comes with Docker Compose, which helps you install the app. To identify multiple containers, Docker Swarm has YAML files (YAML Ain’t Markup Language).
- CONFIGURING THE CONTAINER
Although the Docker Swarm API does not support all Docker commands, it offers almost all of the best Docker functionality.
So, Docker Swarm supports most of the tools available for Docker. However, if the Docker API is not able to perform some necessary operations, there is no easy workaround for using them in Docker Swarm.
Like Docker Swarm, Kubernetes has its own version of the API, client definitions, and YAML. However, they are different from their Docker counterparts.
Therefore, it is not possible to use the Docker CLI or Docker Compose to define containers in Kubernetes. In cases where you need to switch platforms, YAML commands and definitions need to be rewritten.
- LOAD BALANCING
Ingress is usually used for load balancing in Kubernetes. However, there is another way in which a module in Kubernetes is exposed through a service and can be used as a load balancer in the cluster to which it belongs.
Docker Swarm has a DNS element that can be used to distribute incoming requests by a specific service name. For load balancing, services can be assigned automatically or configured to run on user-specified ports.
- NETWORK
Kubernetes uses a flat network model. In this way, all modules can interact with each other. How the modules interact is determined by network policies. Usually, the flat network model is implemented as an overlay.
The flat network model in Kubernetes requires two cidrs (Classless Inter-Domain Routing): one for services, and the other from which modules get an IP address.
In Docker Swarm, a node that joins a Swarm cluster is responsible for generating an overlay network for services that spans each host in the cluster, and a Docker bridge network for container hosts only.
Docker Swarm allows users to encrypt container data traffic when creating an overlay network.
- SCALABILITY
Kubernetes is a comprehensive framework for distributed systems. Because it offers a unified set of APIs and robust cluster state guarantees, Kubernetes is a complex system. These abilities are responsible for slowing down the deployment and scaling of the container.
Compared to Kubernetes, Docker Swarm can deploy containers at a much faster speed. Therefore, it allows you to respond faster to scaling the system to meet the requirements.
Synergy between Docker and Kubernetes
Kubernetes can work in tandem with any containerization technology. GLUE and Docker are the two most popular options for the open source container orchestration engine. However, the latter is preferable to the former.
Due to the greater preference for using Docker with Kubernetes, much effort has been made to improve collaboration between the two technologies.
Although Docker has its own container orchestration mechanism in the form of Docker Swarm, the propensity to use Kubernetes with Docker cannot be overlooked. This is evident from the fact that Docker for Desktop comes with its own Kubernetes distribution.
Therefore, it is clear that both technologies, Docker and Kubernetes, have joined forces and also benefited greatly from this collaboration.
