Why Choose K3s Over K8s? A Lightweight Kubernetes Comparison

Kubernetes, often abbreviated as K8s, is the leading container orchestration tool. This open‑source project was originally developed by Google and defines modern orchestration. The system includes everything needed to deploy and run containerized workloads.

Community vendors have created independent distributions of Kubernetes for different use cases. K3s is a popular distribution created by Rancher and now maintained as part of the Cloud Native Computing Foundation (CNCF).

K3s aims to be a lightweight Kubernetes version suitable for resource‑constrained hardware such as IoT devices. It is easy to set up and use, making it ideal for local development clusters. While focused on edge deployments, it also supports large‑scale cloud deployments. Its CNCF certification means it provides all Kubernetes features and can be used in production.

This article compares K3s with the official Kubernetes distribution, covering their differences, when to use each, and how easy they are to master.

What Is K8s

Kubernetes is an open‑source container orchestration engine that automates deployment, scaling, and management of containerized applications. The project is hosted by the CNCF.

Kubernetes provides all the tools needed to deploy containers and scale them across multiple hosts. Each host in a Kubernetes cluster is called a node and is managed by the control plane, which schedules containers onto idle nodes, manages networking and storage, and exposes an API for interaction.

What Is K3s

K3s is a Kubernetes distribution led by Rancher. It builds on the upstream project without forking. Conceptually, a Kubernetes distribution is like a Linux distribution: K3s is to Kubernetes what Ubuntu is to Linux. K3s retains all Kubernetes functionality while adding its own features.

K3s is specially designed to run well even on minimal hardware. It provides a single binary smaller than 60 MB that contains everything needed to start a fully functional Kubernetes cluster.

By dropping non‑essential Kubernetes features such as cloud‑provider integrations and non‑CSI storage providers, K3s achieves this small binary size. It leverages Go goroutines to run the various Kubernetes components from a single entry point.

K3s and K8s Deployment Ease

Generally, K3s is easier to deploy and maintain than K8s. The lightweight binary lets you start all Kubernetes control‑plane components with a single command, whereas launching an official Kubernetes cluster requires more time, steps, and maintenance.

Deploy K3s

The following command starts and runs a K3s cluster: $ curl -sFL https://get.k3s.io | sh - The official install script downloads the binary and registers a system service that automatically starts K3s on process termination or host reboot. It also configures Kubernetes utilities, including the kubectl CLI. After running the script on a new machine, you can interact with the cluster within seconds:

$ kubectl run nginx --image=nginx
pod/nginx created

You can add additional nodes by running on other machines:

$ sudo k3s agent --server https://<control-plane-ip>:6443 \
--token <node-token>

The node token can be obtained from the control‑plane machine by reading the file /var/lib/rancher/k3s/server/node-token.

K3s can also be deployed with k3d , which packages K3s inside Docker containers. Install k3d with:

$ curl -s https://raw.githubusercontent.com/k3d-io/k3d/main/install.sh | \
TAG=v5.4.5 bash

Then create your first cluster: $ k3d create cluster demo-cluster Use kubectl to add objects to the k3d/K3s cluster:

$ kubectl run nginx --image nginx:latest
pod/nginx created

Deploy K8s

K8s deployment is more complex. The Kubernetes project provides separate component binaries such as the API server, controller manager, and scheduler. You must successfully deploy each component to create the control plane, then install kubelet on each worker node.

Using the kubeadm tool simplifies installation. Before using kubeadm, you need a container runtime like containerd . Initialize the control plane with: $ kubeadm init After initialization, set up your kubeconfig:

$ mkdir -p $HOME/.kube
$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
$ sudo chown $(id -u):$(id -g) $HOME/.kube/config

Install a pod network plugin (e.g., Flannel) so pods can communicate:

$ kubectl apply -f https://raw.githubusercontent.com/flannel-io/flannel/master/Documentation/kube-flannel.yaml

Join additional nodes with:

$ kubeadm join --token <token> <control-plane-ip>:<control-plane-port> \
--discovery-token-ca-cert-hash sha256:<hash>

The token value is obtained via kubeadm token list on the control‑plane host, and the discovery hash can be generated with:

openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | \
openssl rsa -pubin -outform der 2>/dev/null | \
openssl dgst -sha256 -hex | sed 's/^.* //'

Using kubeadm to start a local Kubernetes cluster is considerably more involved than using K3s, which abstracts many steps for a quick start.

Main Differences Between K3s and K8s

K8s and K3s expose the same functional API. A Kubernetes YAML manifest works unchanged on both clusters.

The differences lie in packaging and included components. Notably, the control‑plane data store: upstream Kubernetes uses etcd, while K3s defaults to an embedded SQLite database, improving performance and reducing binary size. K3s can also connect to external etcd or SQL databases such as MySQL or PostgreSQL.

Standard Kubernetes distributions include only the components required for the control plane. K3s bundles additional common tools like kubectl and integrates Helm support via a native HelmChart resource, whereas upstream Kubernetes requires a separate Helm CLI.

Both use containerd as the default container runtime, but K3s also includes community components such as Flannel for pod networking and Traefik as an ingress controller and load balancer. Kubernetes leaves these choices to the user.

When you want to avoid spending time learning each component’s role, K3s is the better choice; it can start a fully functional cluster suitable for production.

Resource Requirements

K3s can run on devices with 1 CPU and 512 MB of memory; its binary is under 60 MB and has no external dependencies.

Clusters created with kubeadm have higher resource demands. Documentation recommends at least two idle CPU cores and 2 GB of RAM. The added control‑plane overhead means more hardware is needed to achieve comparable results, which can increase cloud costs.

K3s is the preferred option for resource‑constrained environments, though running it on the absolute minimum (512 MB) is not recommended because applications also need headroom.

Upgrade Experience

K3s offers a simplified upgrade experience. Running the install script again downloads the latest version and upgrades automatically: $ curl -sfL https://get.k3s.io | sh - Repeating this command on each node upgrades the entire cluster without manual intervention.

Upgrading a kubeadm ‑based K8s cluster requires several additional steps: install the new kubeadm version, upgrade the control plane, then upgrade each worker’s kubelet and kubectl:

# Updating to v1.24.1
$ apt-get update
$ apt-get install -y kubeadm=1.24.1
$ kubeadm upgrade apply v1.24.1
$ apt-get update
$ apt-get install -y kubelet=1.24.1 kubectl=1.24.1
$ systemctl daemon-reload
$ systemctl restart kubelet

K3s again provides a simpler, hands‑off upgrade, whereas kubeadm involves more commands and a higher chance of errors.

Speed

On equivalent hardware, K8s and K3s clusters run containers with similar performance because they share the same containerd runtime. However, K3s’s lightweight nature makes its control‑plane installation and startup much faster; K3s is often ready within a minute, while upstream Kubernetes may take several minutes.

Security

K3s is designed with a minimal attack surface; all components are packaged into a single binary, reducing the likelihood of vulnerabilities.

This does not mean K8s is insecure. Kubernetes is the most popular open‑source project, widely adopted and regularly audited to protect clusters from attacks.

Regardless of the solution, you should harden your cluster after installation. Both K3s and Kubernetes provide their own security recommendations for building secure clusters.

Ideal Use Cases for K3s and K8s

K3s’s low hardware requirements make it suitable for resource‑constrained environments that cannot host a standard K8s cluster. By omitting components like etcd and using smaller alternatives, K3s fits IoT and edge devices.

K3s is also ideal for local development and testing environments. Engineers can spin up a cluster in seconds without installing dependencies or incurring cloud costs. It can even run in CI pipelines to simplify testing.

In scenarios requiring large‑scale deployments or specific Kubernetes components, a full‑featured distribution may be more appropriate. For massive clusters where you need full control over each control‑plane component, K3s’s simplicity might be limiting.

Conclusion

Kubernetes remains the leading tool for deploying and distributing containers, but the vanilla platform is complex and hard to maintain.

K3s addresses these challenges by offering a CNCF‑certified Kubernetes distribution packaged as a single binary under 60 MB. Its lightweight approach lets you run the same Kubernetes version on edge devices, workstations, and traditional cloud environments.