K3s vs K8s: Understanding the Differences and Making the Right Choice

Introduction

In the world of container orchestration, Kubernetes (K8s) has established itself as the go-to solution for managing containerized applications. However, its complexity and resource demands can be a challenge for smaller environments or edge computing. Enter K3s, a lightweight Kubernetes distribution designed to tackle these challenges. This blog will delve into what K8s and K3s are, their differences, architectures, advantages, disadvantages, and how to choose the right one for your needs.

What is Kubernetes (K8s)?

Kubernetes, or K8s, is an open-source platform for automating containerized application deployment, scaling, and operations. It offers a robust framework to manage distributed systems, ensuring applications run efficiently and resiliently.

Key Features of K8s:

• Container Orchestration: Automates deployment, scaling, and management.
• Service Discovery and Load Balancing: Efficiently manages service endpoints and balances traffic.
• Storage Orchestration: Supports various storage systems for persistent storage needs.
• Automated Rollouts and Rollbacks: Manages application updates seamlessly.
• Self-Healing: Automatically restarts failed containers and replaces unhealthy ones.
• Secret and Configuration Management: Securely manages sensitive data and configurations.

K8s Architecture:

Kubernetes follows a master-worker architecture, consisting of the following components

Master Node:

• API Server: Exposes the Kubernetes API.
• etcd: A consistent and highly-available key-value database used for configuration data.
• Scheduler: Distributes workloads across nodes.
• Controller Manager: Ensures the desired state of the cluster.

Worker Nodes:

• Kubelet: Ensures containers are running in a Pod.
• Kube-proxy: Maintains network rules and load balancing.
• Container Runtime: Runs the containers (e.g., Docker, containerd)

What is K3s?

K3s, developed by Rancher Labs, is a lightweight Kubernetes distribution that retains the core functionalities of K8s while being more resource-efficient. Designed for edge computing, IoT devices, and development environments, K3s reduces the "bloat" from stock Kubernetes. The single binary ranges from under 40MB to 100MB and runs on less than 512MB of RAM. Rancher created K3s during the development of RIO, a now-defunct PaaS on Kubernetes. The project was later opened to the community and donated to the CNCF, which now regulates both K8s and K3s. Rancher achieved this by removing over 3 billion lines of unnecessary code, including non-CSI storage providers, alpha features, and legacy components.

K3s Architecture:

K3s follows a simplified architecture with the following components:

Key Features of K3s:

• Lightweight: Reduced memory and CPU usage, ideal for resource-constrained environments.
• Single Binary: All Kubernetes components are packaged into a single binary, reducing the footprint.
• Embedded Database: Uses SQLite by default, with options for MySQL, Postgres, or etcd.
• Single-Node Clusters: Supports single-node mode, suitable for edge use cases.
• Simplified Components: Strips out non-essential components, which can be added if needed.
• Optimized for ARM: Designed to run efficiently on ARM processors.

K3s vs K8s: A Side-by-Side Comparison

While K3s and K8s share the same core functionalities, they differ significantly in their architecture, resource requirements, and use cases.

Kubernetes (K8s) Advantages:

• Scalability: Scales to thousands of nodes and containers.
• Extensibility: Rich ecosystem with many integrations and extensions.
• Flexibility: Supports various deployment configurations and cloud providers.
• High Availability: Robust support for HA setups.

Kubernetes (K8s) Disadvantages:

• Complexity: Steep learning curve and complex setup process.
• Resource Intensive: Requires significant CPU, memory, and storage resources.
• Operational Overhead: Requires ongoing management and maintenance.

K3s Advantages:

• Lightweight: Minimal resource consumption, suitable for edge and IoT devices.
• Simplified Installation: Easy to set up with a single binary.
• Reduced Complexity: Fewer dependencies and components to manage.
• ARM Optimized: Efficiently runs on ARM processors.

K3s Disadvantages:

• Limited Features: Strips out some advanced features of K8s.
• Single-Node Clusters: Less suitable for large-scale, multi-node clusters.
• Database Flexibility: Default SQLite may not be suitable for all use cases, requiring external databases for larger deployments.

When to Choose K3s vs. K8S

K3s: Ideal for Small Deployments

Edge Computing:Edge computing improves performance, latency, and security by running applications closer to data sources or users. Use cases include autonomous vehicles, video streaming, gaming etc. K3s can efficiently run on these devices with minimal resources, providing a consistent Kubernetes experience.

IoT Devices:IoT applications connect various devices and sensors, often requiring real-time processing and communication. K3s, with its lightweight design, can run directly on devices or nearby edge nodes, making it ideal for low-power embedded or IoT gateways with limited resources. Kubernetes would be excessive for these scenarios.

Limited Infrastructure:K3s operates effectively with limited networking, storage, or automation capabilities, making it easier to manage than full Kubernetes. It runs without external dependencies and works with local or network-attached storage, featuring built-in automation like certificate management, cluster registration, and backup/restore.

Small Clusters:For deployments involving a small number of nodes, K3s simplifies both the setup and operational processes compared to full Kubernetes. It can run on any Linux machine, even those with limited resources, while ensuring a reliable and secure Kubernetes environment.

Low-Power Hardware:K3s is ideal for single-board computers, network appliances, and other compact devices, supporting ARM architectures and container runtimes like containerd or cri-o. It operates seamlessly on devices such as Raspberry Pi, Intel NUC, NVIDIA Jetson Nano, BeagleBone, ASUS Tinker Board, and Odroid, among others.

Development/Testing:K3s quickly sets up local test environments. It can run on local or virtual machines, allowing realistic Kubernetes testing. Tools like k3d and k3sup facilitate the creation and management of multiple K3s clusters.

Kubernetes Familiarity:Teams familiar with Kubernetes concepts and tools will find K3s an easy migration option, using the same APIs, primitives, and tools as Kubernetes. Helm charts, kubectl commands, and custom resource definitions work seamlessly with K3s.

K8s: Powering Complex Applications

For heavy-duty clusters, Kubernetes (K8s) is the top choice. While K3s is specifically designed for running Kubernetes on bare metal servers, K8s serves as a general container orchestrator with a wide range of configuration options for different applications.

If you need high-availability features like automatic failover and cluster-level redundancy, K8s is likely the better option. K8s also provides numerous extensions, dependencies, and features, such as load balancing, auto-scaling, and service discovery.

K8s is particularly well-suited for cloud-native applications and complex microservices. With its APIs, operational functions, and support for tools like Istio and Prometheus, K8s aligns well with the needs of stateful, intricate cloud-native apps, offering capabilities and integrations that enhance development, deployment, and management.

Additionally, K8s can manage complex applications, including advanced big data analytics and high-performance computing. It's also optimized for nodes with substantial hardware resources like RAM, multiple CPUs, and SSDs. For critical production apps with stringent high availability requirements, K8s's resilience makes it a preferred choice over K3s's simplicity.

In the long term, both small and large companies can utilize K8s to manage intricate applications with multiple extensions, cloud provider add-ons, and external drivers effectively.

Conclusion

Both K3s and K8s offer robust container orchestration capabilities, but they are designed to address different challenges. K8s excels in managing large-scale, complex environments with extensive features and high availability. It is ideal for cloud-native applications, big data analytics, and high-performance computing, where substantial hardware resources and scalability are crucial.

On the other hand, K3s shines in resource-constrained scenarios, such as edge computing, IoT devices, and small clusters. Its lightweight architecture and ease of installation make it perfect for environments with limited infrastructure and low-power hardware.

Ultimately, choosing between K3s and K8s depends on your specific requirements, resource availability, and operational goals. By understanding the strengths and differences of each, you can select the right tool to ensure efficient and effective container orchestration for your applications. Whether you need the full power of K8s or the streamlined efficiency of K3s, both options provide the benefits of Kubernetes tailored to different deployment scenarios.