Lightweight Kubernetes: k3s vs k0s vs microk8s

Introduction

By mid-2019, the Kubernetes ecosystem had expanded beyond full-featured distributions to include lightweight alternatives designed for resource-constrained environments. k3s (Rancher Labs, March 2019), k0s (Mirantis, preview), and microk8s (Canonical) emerged as single-binary or minimal-footprint options for edge computing, IoT devices, and local development.

This mattered because traditional Kubernetes (kubeadm, managed services) required significant resources—multiple nodes, gigabytes of RAM, and complex networking. Lightweight distributions made Kubernetes accessible for Raspberry Pi clusters, edge devices, CI/CD runners, and developer laptops where full Kubernetes was impractical.

Historical note: k3s’s launch in March 2019 marked the first major lightweight Kubernetes distribution to gain widespread adoption. k0s would follow later in 2019 as a preview, and microk8s had been evolving since 2018.

k3s Highlights

• Single Binary: All Kubernetes components packaged into a single ~40MB binary.
• SQLite Backend: Uses SQLite instead of etcd for single-node simplicity (etcd available for HA).
• Removed Components: Strips out non-essential components (cloud providers, legacy APIs, in-tree plugins).
• ARM Support: Excellent ARM64 and ARM32 support for edge devices.
• Rancher Integration: Built by Rancher Labs with integration into Rancher management platform.
• Installation: One-command install: curl -sfL https://get.k3s.io | sh -

k0s Highlights (Preview 2019)

• Zero-Friction: Single binary with no host OS dependencies (no Docker required).
• Container Runtime Agnostic: Works with containerd, CRI-O, or Docker.
• Minimal Footprint: Designed for absolute minimal resource usage.
• Air-Gapped Ready: Can be deployed in completely offline environments.
• Mirantis Backing: Developed by Mirantis with enterprise support options.

microk8s Highlights

• Snap-Based: Installed via Canonical’s snap package manager.
• Add-On System: Built-in add-ons (DNS, storage, ingress, dashboard) via microk8s enable.
• Multi-Node: Native support for multi-node clusters.
• Ubuntu Optimized: Best experience on Ubuntu, works on other Linux distributions.
• Canonical Support: Official Canonical support and enterprise options.

Feature Comparison (Mid-2019)

Use Cases

Edge Computing

All three distributions excel in edge computing scenarios:

• k3s: Best for Rancher-managed edge deployments with centralized management.
• k0s: Ideal for air-gapped edge environments with minimal dependencies.
• microk8s: Good for Ubuntu-based edge devices with add-on requirements.

IoT Devices

• k3s: Excellent ARM support makes it ideal for Raspberry Pi and ARM-based IoT devices.
• k0s: Minimal footprint suits resource-constrained IoT devices.
• microk8s: Less suitable for very constrained devices due to snap overhead.

Local Development

• k3s: Fast startup, low resource usage, good for local Kubernetes development.
• k0s: Fast and lightweight, but preview status may have stability concerns.
• microk8s: Easiest add-on management with enable commands, good for learning.

CI/CD Testing

• k3s: Fast cluster creation makes it ideal for CI/CD pipelines.
• k0s: Single binary deployment simplifies CI/CD integration.
• microk8s: Snap-based installation can be slower in CI/CD environments.

Resource Footprint Comparison

Single Node Cluster

Multi-Node Cluster (3 nodes)

Getting Started

k3s

# Single node
curl -sfL https://get.k3s.io | sh -

# Multi-node (server)
curl -sfL https://get.k3s.io | K3S_TOKEN=my-secret-token sh -s - server

# Multi-node (agent)
curl -sfL https://get.k3s.io | K3S_TOKEN=my-secret-token K3S_URL=https://master:6443 sh -

k0s (Preview)

# Download binary
wget https://github.com/k0sproject/k0s/releases/download/v0.1.0/k0s-v0.1.0-linux-amd64
chmod +x k0s-v0.1.0-linux-amd64
sudo mv k0s-v0.1.0-linux-amd64 /usr/local/bin/k0s

# Create cluster
sudo k0s install controller
sudo k0s start

microk8s

# Install
snap install microk8s --classic

# Enable add-ons
microk8s enable dns
microk8s enable storage
microk8s enable ingress
microk8s enable dashboard

# Add node
microk8s add-node

Practical Considerations

Production Readiness

• k3s: Production-ready with Rancher support and active development.
• k0s: Preview status in 2019; not recommended for production until GA.
• microk8s: Production-ready with Canonical support, best on Ubuntu.

Networking

• k3s: Uses Flannel by default (VXLAN); can use other CNIs.
• k0s: Requires CNI installation; no default networking.
• microk8s: Uses Calico by default; can switch CNIs.

Storage

• k3s: Local path provisioner included; can add other storage classes.
• k0s: No default storage; requires manual storage class configuration.
• microk8s: Hostpath storage included; can enable other storage backends.

Add-On Management

• k3s: Manual installation via manifests or Helm.
• k0s: Manual installation; no built-in add-on system.
• microk8s: Built-in enable command for common add-ons (DNS, storage, ingress, dashboard).

Choosing the Right Lightweight Distribution

Choose k3s When:

• Rancher Integration: Using or planning to use Rancher for cluster management.
• ARM Devices: Deploying on Raspberry Pi or ARM-based edge devices.
• Single Binary Preference: Want a single-binary deployment model.
• Production Edge: Need production-ready lightweight Kubernetes.

Choose k0s When:

• Minimal Dependencies: Need absolute minimal footprint with no host OS dependencies.
• Air-Gapped: Deploying in completely offline environments.
• Container Runtime Flexibility: Need to choose between containerd, CRI-O, or Docker.
• Future-Proofing: Want to evaluate cutting-edge lightweight Kubernetes (preview status).

Choose microk8s When:

• Ubuntu Environment: Running on Ubuntu or snap-supported distributions.
• Easy Add-Ons: Want built-in add-on management with enable commands.
• Learning Kubernetes: Need an easy way to experiment with Kubernetes features.
• Canonical Ecosystem: Using other Canonical tools or services.

Caveats & Lessons Learned

• Compatibility: Lightweight distributions may not support all Kubernetes features; verify API compatibility.
• Add-On Compatibility: Some Helm charts or operators may not work on lightweight distributions.
• Resource Limits: Even lightweight distributions need adequate resources; don’t over-constrain.
• Networking: Networking behavior may differ from full Kubernetes; test network policies and services.

Common Failure Modes

• “Out of memory”: Lightweight doesn’t mean zero resources; ensure adequate RAM.
• “Add-on incompatibility”: Some add-ons expect full Kubernetes; test compatibility before deploying.
• “Network issues”: Networking implementations differ; verify CNI compatibility.

Conclusion

The emergence of lightweight Kubernetes distributions in 2019 expanded Kubernetes’ reach beyond data centers to edge devices, IoT, and resource-constrained environments. k3s, k0s, and microk8s each offered different trade-offs: k3s for Rancher integration and ARM support, k0s for minimal dependencies and air-gapped deployments, and microk8s for easy add-on management and Ubuntu optimization.

While full Kubernetes (kubeadm, managed services) remained the standard for production data centers, lightweight distributions opened new possibilities: Raspberry Pi clusters, edge computing, local development, and CI/CD testing. They proved that Kubernetes could be both powerful and lightweight, making container orchestration accessible to a broader range of use cases and environments.

For teams evaluating lightweight distributions, the choice came down to specific needs: Rancher integration (k3s), minimal dependencies (k0s), or easy add-ons (microk8s). All three demonstrated that Kubernetes didn’t have to be heavyweight to be powerful.