Kubernetes vs Docker Swarm: Comparison of Two Container Orchestration Tools

With the rise of containerization technology and increased attention from enterprises and technologists in general, more and more containerized applications have been deployed to the cloud. Moreover, research conducted by 451 Research predicts that the application container market will grow dramatically through 2020, which will continue to expand the number of containerized applications being deployed to the cloud.

When the scale and complexity of production-critical containers rises, container orchestration tools come into the picture and become an indispensable part of enterprises’ container management toolbox. Kubernetes and Docker Swarm are two famous, leading players in the container orchestration market and become the essential part of microservices of many enterprises. This article will give you an overview of each container orchestrator and offer a comparison of Kubernetes vs Docker Swarm based on:

• Cluster Setup and Configuration
• Administration
• Auto-scaling
• Load Balancing
• Storage
• Market Share

Overview of Kubernetes

Kubernetes is an open-source, community-driven Container Orchestration Engine (COE) inspired by a Google project called Borg. Kubernetes is used to orchestrate fleets of containers representing instances of applications that are decoupled from the machines they run on. As the number of containers in a cluster increases to hundreds or thousands of instances, with application components deployed as separate containers, Kubernetes comes to the rescue by providing a framework for deployment, management, auto-scaling, high availability, and related tasks.

Kubernetes allows you to handle various container orchestration related tasks such as scaling containers up or down, automatic failover, distributing workloads among containers hosted on different machines.

Kubernetes follows the traditional client-server type of architecture where the Master node has the global view of the cluster and is responsible for the decision making. Users can interact with the Master node through the REST API, the web UI, and the command line interface (CLI). The Master node interacts with the Worker nodes that host the containerized applications.

Some of the common terminology used within the Kubernetes ecosystem are:

• Container: Containers are the units of packaging used to bundle application binaries together with their dependencies, configuration, framework, and libraries.
• Pods: Pods are the deployment units in Kubernetes ecosystem which contains one or more containers together on the same node. Group of containers can work together and share the resources to achieve the same goal.
• Node: A node is the representation of a single machine in the cluster running Kubernetes applications. A node can be a physical, bare metal machine or a virtual machine.
• Cluster: Several Nodes are connected to each other to form a cluster to pool resources that are shared by the applications deployed onto the cluster.
• Persistent Volume: Since the containers can join and leave the computing environment dynamically, local data storage can be volatile. Persistent volumes help store container data more permanently.

Overview of Docker Swarm

Docker Swarm is an alternative, Docker-native Container Orchestration Engine that coordinates container placement and management among multiple Docker Engine hosts. Docker Swarm allows you to communicate directly with swarm instead of communicating with each Docker Engine individually. Docker Swarm architecture comprises two types of nodes called Managers and Workers.

Below are the common terminology used in the Docker Swarm ecosystem:

• Node: A node is a machine that runs an instance of Docker Engine
• Swarm: A cluster of Docker Engine instances.
• Manager Node: Manager nodes distribute and schedule incoming tasks onto the Worker nodes and maintains the cluster state. Manager Nodes can also optionally run services for Worker nodes.
• Worker Node: Worker nodes are instances of Docker Engine responsible for running applications in containers.
• Service: A service is an image of a microservice, such as web or database servers.
• Task: A service scheduled to run on a Worker node.

Comparison of Kubernetes vs Docker Swarm Features

Both Kubernetes and Docker Swarm COEs have advantages and disadvantages, and the best fit will largely depend on your requirements. Below we compare a few features they share.

Conclusion

The Kubernetes vs Docker Swarm comparison shows that each container orchestrator has advantages and disadvantages:

If you require a quick setup and have simple configuration requirements, Docker Swarm may be a good option due to its simplicity and shallow learning curve.

If your application is complex and utilizes hundreds of thousands of containers in production, Kubernetes, with its auto scaling capabilities and high availability policies, is almost certainly the right choice. However, its steep learning curve and longer setup and configuration time can be a bad fit for some users. With additional tooling, like Rancher, some of these administration and maintenance pain points can be mitigated, making the platform more accessible.

More Resources

A good next step in learning about container orchestration and what Kubernetes can do is to book a spot in our weekly Intro to Rancher and Kubernetes Online Training. An engineer will walk you through Kubernetes architecture, components and setup, and then show you the value that Rancher adds on top of Kubernetes. Register for the online class now.