Docker Swarm vs k3s: What are the differences?

Introduction

Docker Swarm and k3s are both container orchestration platforms used to manage and scale containerized applications. While they share similarities, there are key differences between the two.

1. Scalability and Complexity: Docker Swarm is a more mature and feature-rich orchestration tool compared to k3s. It allows scaling to thousands of nodes and supports advanced features like service discovery, load balancing, and rolling updates. On the other hand, k3s is designed to be lightweight and lightweight, suitable for resource-constrained environments like IoT devices or edge computing. It sacrifices some advanced features for simplicity and ease of use.

2. Installation and Resource Requirements: Docker Swarm requires a Docker daemon on each node, which leads to higher resource utilization. It also needs a dedicated manager node for cluster coordination. In contrast, k3s is a single binary that includes both the Kubernetes components and container runtime. It has minimal resource requirements, making it easier to install and run on low-spec devices.

3. Community Support and Ecosystem: Docker Swarm has a larger and more established community compared to k3s. It has been around for a longer time, resulting in a wider range of tools, integrations, and community support available. Conversely, k3s is relatively new but has gained popularity due to its lightweight nature. However, the ecosystem around k3s is still evolving and may have fewer options compared to Docker Swarm.

4. Networking and Service Discovery: Docker Swarm uses an embedded DNS server for service discovery and assigns a virtual IP to each service. It supports overlay networks for multi-host communication. K3s, being a lightweight Kubernetes distribution, relies on Kubernetes networking models like Service Objects and DNS for service resolution. It provides more advanced networking capabilities and integrates seamlessly with other Kubernetes components.

5. Security and Authentication: Docker Swarm uses Docker's built-in security mechanisms for authentication and access control, such as TLS certificates and role-based access control (RBAC). It provides a simplified approach to security and is well-suited for environments where Docker is already being used extensively. K3s, being Kubernetes-based, leverages its robust security features, including RBAC, pod security policies, and network policies. It offers granular control and can be integrated into existing Kubernetes security frameworks.

6. Ease of Management and Operation: Docker Swarm has a straightforward and intuitive management interface, allowing users to quickly set up and scale their clusters. It provides a simple API and CLI for managing services, nodes, and configurations. K3s, although lighter, follows the Kubernetes tooling and workflows. It provides a flexible and powerful command-line interface for managing and configuring Kubernetes resources but requires familiarity with Kubernetes concepts and YAML-based configuration files.

In summary, Docker Swarm is a mature and feature-rich orchestration platform suitable for large-scale deployments, while k3s is a lightweight Kubernetes distribution geared towards resource-constrained environments. Docker Swarm offers advanced features and a larger ecosystem, while k3s prioritizes simplicity, ease of installation, and performance on low-spec devices.