Education Ecosystem Blog

Source: Devops.com

Kubernetes vs. Docker Swarm is a simple comparison of two orchestration mechanisms for building, deploying, and running containers inside clusters for a microservices architecture. 

This article will explore some basics of Docker Swarm and Kubernetes, the similarities between them, discuss their differences, their pros, and cons, and at the end, the verdict; which one to go for.

What is Kubernetes?

Kubernetes is an open-source, cloud-native infrastructure tool that automates containerized applications’ scaling, deployment, and management. As Barnabas demonstrates in his project, it places containers into groups, naming them as logical units and mitigating the problems with running applications in public and private clouds. 

What is Docker Swarm?

Docker Swarm is native to the Docker platform. It is a container orchestration tool native to Docker that enables applications to run seamlessly across multiple nodes that share the same containers. In essence, the Docker Swarm model is used to efficiently manage, deploy, and scale a cluster of nodes on Docker.

Comparing Kubernetes and Docker Swarm for single-host implementations

How similar and different are Kubernetes and Docker Swarm with respect to;

1. Set up, Installation and their Cluster Configuration

Kubernetes: Installing Kubernetes is easy when installing it in a testbed. Although if you plan to run it at scale, it requires a bit more planning and effort.

Docker Swarm: Docker Swarm uses the Docker CLI to run its programs. Therefore, knowledge about only a single set of tools needs to be learned to build environments and configurations. 

2. Building and Running Containers

Kubernetes: Kubernetes is unique since it has its own API, client, and YAML definitions. This is in high contrast to the standard Docker equivalents since it is impossible to use Docker Compose or Docker CLI in defining containers.

Docker Swarm: Docker CLI is used, and new containers can be spun using a single command. The Swarm API supports multiple tools working with Docker, although it can be a hassle if Docker lacks a specific operation, as Elliot, Education Ecosystem creator, demonstrates.

3. Logging and Monitoring

Kubernetes: Kubernetes has inbuilt tools for Logging and Monitoring. Logging helps in understanding the cause of failures through the analysis of past logs. 

Docker Swarm: Swarm lacks inbuilt tools to handle Logging and Monitoring. Although, one can make use of third-party tools to achieve this. ELK is one such tool. Other tools such as Reimann can be used for monitoring.

4. Load Balancing

Kubernetes: Load Balancing is available in Kubernetes when Container Pods are defined as Services. One still need to configure the load balancing settings manually. Only a particular set of pods and policies give access to each service.

Docker Swarm: Swarm provides an inbuilt option of Load Balancing. A typical network is joined by all containers that are in the same cluster. This allows the connection of any node to any container.

5. Availability

Kubernetes allows two topologies by default. These ensure high availability by creating clusters to eliminate single points of failure. These are;

• Stacked Control Plane nodes ensure availability by co-locating etcd objects with all available nodes of a cluster during a failover.
• External etcd objects for load balancing while controlling the control plane nodes separately. 

Notably, both methods leverage using kubeadm and use a Multi-Master approach to maintain high availability by keeping etcd cluster nodes either externally or internally within a control plane.

To maintain high availability, Docker uses service replication at the Swarm Nodes level. By doing so, a Swarm Manager deploys multiple instances of the same container, with replicas of services in each. 

6. Scalability

Kubernetes: Kubernetes is slightly better than Swarm when it comes to maintaining the strength of the clusters. However, it is not as scalable as Swarm owing to the complexity involved. A unified set of APIs adds complexity to Kubernetes, along with a strong focus on the cluster state.

When it comes to Auto-scaling, Kubernetes can analyze the server load and scale up or down in tandem with your requirements. 

Docker Swarm: Containers can be deployed faster in large clusters, and high cluster fills stages. A single update command deploys new replicas.

Auto-scaling is smooth with Swarm just as it is with Kubernetes, but with the help of StackStorm, AWS autoscaling is possible. 

7. GUI

Kubernetes: The GUI provided is a reliable dashboard that can be used to control the cluster effortlessly. This can be a huge boon for you if you are not from a technical background since it requires no technical efforts and the instructions are in plain English.

Docker Swarm: Docker hosts and Swarm Clusters can be managed with the help of a third-party tool such as Portainer.io that provides an easy management UI. On the other hand, the Universal Control Pane in Docker Enterprise edition provides you an interface to manage the clusters.

Pros and Cons

How do the pros and cons of Kubernetes and Docker Swarm compare?

Summary — Kubernetes or Docker Swarm?

The greater purpose of Kubernetes and Docker Swarm overlaps each other. But, as the article outlines, there are similarities as well as fundamental differences between how the two operate.  All in all, both options solve advanced challenges to make the digital transformation realistic and efficient.