K3s vs K8s: Differences, Use Cases & Alternatives

Kubernetes (K8s) is the leading container orchestrator for operating containerized applications in production environments. It automates key container management tasks, including deployment, scaling, and fault tolerance.

There’s no single Kubernetes distribution, however. Just as Linux is available in different flavors such as Ubuntu and Fedora, you can choose from several other Kubernetes distributions, depending on your requirements. 

In this guide, we’ll explore the differences between K8s and K3s: a popular lightweight option for Kubernetes distribution.

1. What is Kubernetes (K8s)?
2. What is K3s?
3. K3s vs K8s: What is the difference?
4. Benefits of using K3s
5. What are the disadvantages of K3s?
6. Guide: Creating a K8s cluster with K3s
7. Alternatives to K3s
8. k8s vs k3s vs k0s

Kubernetes is an open-source system for deploying and operating containers. Clusters consist of a centralized control plane and multiple worker Nodes. The control plane is responsible for managing your containers and scheduling new instances onto available Nodes.

All Kubernetes clusters run a set of core components that fulfill these functions, including the Kubernetes API server, controller manager, and scheduler, as well as a database that stores cluster data and a container runtime that actually runs containers on your Nodes. These components can be packaged in different ways or even replaced by alternative options, depending on the use case that a particular distribution targets.

A vanilla distribution is maintained as part of the Kubernetes project, but this can be complex to set up and maintain. Third-party vendors provide their own distributions that implement all the core Kubernetes functionality but that are easier to use, optimized for specific environments, or extended with additional built-in features.

K3s is a CNCF (Cloud Native Computing Foundation) sandbox project now primarily maintained and supported by SUSE. It is generally considered production-ready fand has gained a solid reputation as a production-grade lightweight Kubernetes distribution.

The name derives from its original aim of delivering a full Kubernetes installation in half the usual memory footprint; just as Kubernetes is a 10-letter word abbreviated as K8s, K3s symbolizes this “half as big” objective. 

K3s is a certified distribution, meaning it’s verified as fully compatible with all standard Kubernetes features. You can write regular Kubernetes manifest files and deploy them to your cluster using standard tools such as Kubectl and Helm. However, there are several differences between K3s and upstream Kubernetes and other distributions.

Unlike a standard Kubernetes install, K3s is packaged as a single binary available for the x86, ARM, and S390X compute architectures and less than 70MB to download. You can start a new cluster by simply running the binary on whichever machine you’re using — no extra dependencies are required. This makes K3s a great fit for resource-constrained IoT and edge computing scenarios, in addition to developer use on local workstations.

Despite its compact footprint, K3s provides a batteries-included Kubernetes experience. It includes the containerd container runtime, Flannel for container networking, and support for provisioning locally-backed Persistent Volumes. 

K3s also bundles the Traefik Ingress controller, which allows you to use Kubernetes Ingress resources without any extra setup, plus a Helm controller that enables declarative management of Helm charts without using the Helm CLI.

To recap, K8s is shorthand for Kubernetes, an open-source system for operating containerized apps in distributed environments. K3s is a certified K8s distribution that packages upstream components into a self-contained binary, alongside customizations that optimize IoT, edge, and local development use cases.

These changes mean K3s clusters don’t exactly match those that run vanilla K8s. Although K3s can do everything that standard Kubernetes can, it’s pared back to reduce external dependencies and keep its binary size small. 

For example, whereas Kubernetes defaults to using etcd to store cluster state, K3s relies on a simpler SQLite database instead. Nonetheless, these differences are unlikely to affect your day-to-day use of K8s features via K3s.

Let’s take a deeper look.

1. Design

K8s is a full-featured container orchestration platform designed for enterprise environments, often requiring significant resources to operate efficiently, whereas K3s is a simplified version of Kubernetes designed to work in resource-constrained environments, such as edge devices, IoT, and smaller clusters.

2. Resource requirements

K3s is optimized for environments with limited resources; it requires less memory and CPU power. Due to its complexity and feature set K8s typically requires substantial resources, including memory, CPU, and storage.

3. Components

K8s has many external dependencies, such as etcd for data storage, and components like kube-apiserver, kube-controller-manager, and kube-scheduler, all running as separate services. 

K3s eliminates many non-essential components and uses a single binary, making it easier and faster to deploy. It removes additional cloud provider dependencies and replaces etcd (the distributed key-value store used by K8s) with an embedded SQLite database by default, though it can be configured to use etcd if needed.

4. Installation and maintenance

K3s’s single-binary approach simplifies upgrades, making it an attractive option for those looking for minimal maintenance. K8s, on the other hand, is known for a more complex installation process that requires a series of steps and configurations, which can be challenging for beginners.

Managed Kubernetes services can simplify K8s installation, but without them, the setup requires a deeper understanding of its components.

5. Use cases

K8s is primarily intended for large, enterprise-grade applications in production environments where high scalability, robustness, and other advanced features are critical. K3s is ideal for edge computing, development, and small deployments. It’s commonly used in scenarios like running Kubernetes on IoT devices, at the network edge, or in local development.

In testing and local development environments, K3s is also useful for emulating Kubernetes using fewer resources, allowing developers to test Kubernetes functionality without needing a full-scale K8s setup.

6. Security

K8s was designed with multi-tenant and enterprise-grade security requirements in mind. It includes a wide range of security features such as Role-Based Access Control (RBAC), Network Policies, and extensive options for managing secrets and encryption.

Although K3s supports RBAC and Network Policies, it omits some security features by default to minimize resource usage. Though it supports helm charts and other Kubernetes-native security tools if necessary, it’s generally optimized for single-tenant environments or edge deployments, where the attack surface may be smaller.

K3v vs K8s table comparison

The table below summarizes the key differences between K3s and K8s:

Is K3s better than K8s?

K3s is better than K8s for lightweight, resource-constrained environments such as edge computing, IoT, or local development because it requires less memory, CPU, and setup complexity. However, K8s is more suitable for enterprise-grade, multi-tenant environments needing high scalability and advanced features.

The choice depends on your deployment needs and resource availability: K3s are simpler and more efficient for smaller setups, and K8s are powerful and flexible for larger, production-grade applications.

Using K3s to operate your Kubernetes cluster offers several advantages over vanilla K8s or alternative distributions:

• Simple set-up experience: As a self-contained binary, K3s is extremely simple to get started with. An installation script is available to automate the process of downloading K3s, registering a system service, and creating a new cluster.
• Convenient extra features included: containerd, Flannel, and Traefik Ingress come pre-installed in your cluster, so you can begin operating your workloads without any additional configuration. It’s still possible to disable these features to replace them with your own preferences.
• Multi-Node deployments supported: K3s seamlessly supports multi-Node deployments involving hundreds or thousands of Nodes. New Nodes can be easily added by running the install script on each one, providing a token that’s generated by the K3s Node serving your cluster’s control plane.
• Ideal for resource-constrained deployments: K3s lets you run Kubernetes clusters in situations where it wouldn’t be possible otherwise. It’s small enough to be operable at the edge and within embedded devices but is still fully compatible with all Kubernetes features.
• Small attack surface improves security: The characteristics that make K3s portable also help boost its security credentials. All components are encapsulated inside a single binary and run as one process, limiting the possible attack surface. Default settings are also adjusted for security.
• Enables standardizing on one K8s distribution for every environment: K3s is ideal if you want to use the same K8s distribution for all your deployments. K3s is equally well-suited to local development use, IoT deployments, and large cloud-hosted clusters that run publicly accessible apps in production.
• Easy to manage and control: K3s lets you stop and start clusters on-demand and you can easily upgrade to new Kubernetes releases by repeating the installation script. It also includes an embedded Kubectl binary, alongside support for backing up your cluster’s data to S3 object storage.

Although we’ve seen that K3s is an attractive K8s distribution for various use cases, alternatives are preferable for other situations.

K3s is simple to set up and manage, but you’re still responsible for maintaining your cluster yourself. Cloud-managed services like Amazon EKS and Google GKE reduce operational complexity by letting you spin up and manage clusters in just a few clicks, or fully automatically via an IaC tool. In addition, K3s leaves you responsible for provisioning and maintaining your compute Nodes, whereas managed solutions will include these tasks as part of their service.

It can also be preferable to stay closer to upstream K8s, particularly if your environments are not significantly resource-constrained. K3s is certified, but it includes component changes that may be undesirable if you’re also running vanilla K8s environments. 

Furthermore, sticking to standard Kubernetes provides the greatest stability when you’re building your own customizations on top.

Ready to give K3s a try? It’s really easy to get started.

You can create a cluster by downloading and running the install script:

A few seconds after the script completes you’ll see the Starting K3s log line — services will still be starting at this point. After a few moments, your cluster should be ready to interact with using Kubectl.

Copy the K3s Kubeconfig file into the .kube folder in your home directory, then adjust the file’s ownership to match your user account:

Set the KUBECONFIG environment variable to the file’s path so Kubectl will load it:

Now try using Kubectl to list your cluster’s Nodes — you should see a single Node, the host that’s running your cluster:

If you don’t already have Kubectl installed, you can use the version that comes bundled with K3s:

Now, you can start deploying workloads to your cluster. To continue your testing, check out the other Kubernetes tutorials on our blog, such as this guide to the Deployment object.

You can stop and start your K3s cluster via its systemd service:

To update to future K3s releases, you should run the install script again after reviewing the upgrade instructions provided in the documentation.

If K3s doesn’t seem to be the right Kubernetes distribution for you, then consider checking out these alternatives instead:

• Minikube: This popular self-contained distribution is maintained as part of the Kubernetes project. It allows you to run a cluster within a Docker container or virtual machine.
• MicroK8s: Maintained by Canonical, MicroK8s is pure-upstream Kubernetes but with customizable features and simplified packaging.
• K0s: A single-binary distribution from Mirantis with an emphasis on set-up speed and simplicity.
• K3d: This isn’t a distribution but instead a wrapper around K3s that runs your cluster inside a Docker container. It can make K3s deployment even easier and safer.
• Kind (Kubernetes IN Docker): This is a tool for running local Kubernetes clusters using Docker container “nodes,” designed primarily for testing and development purposes. It provides a lightweight, easily disposable environment for Kubernetes cluster experimentation without the need for VMs or cloud infrastructure.
• Amazon EKS, Google GKE, Azure AKS, etc.: Cloud-managed K8s services allow you to start new clusters on-demand and usually offer direct connections to your other cloud resources. They also make it easy to auto-scale your clusters with new Nodes as utilization changes, simplifying high availability for production apps.

One final option is to run vanilla K8s by using the Kubeadm tool to start a cluster that runs standard Kubernetes. Although newer releases have simplified the set-up process, it remains relatively involved. Maintenance can also be more complex than when using the third-party distributions mentioned above. Vanilla Kubernetes is generally most useful when you want to build your own advanced customizations.

As mentioned above, K3s isn’t the only K8s distribution whose name recalls the main project. Here’s a reminder of how K8s, K3s, and K0s stack up:

• K8s: Upstream Kubernetes or any distribution that implements its standard features
• K3s: Compact single-binary K8s distribution from SUSE, primarily targeting IoT and edge workloads
• K0s: Single-binary K8s distribution by Mirantis, emphasizing cloud operations in addition to the edge

Both K3s and K0s are good options for your K8s cluster — just remember that, despite the similar names, they’re entirely separate projects.

If you need assistance managing your Kubernetes projects, look at Spacelift. It brings with it a GitOps flow, so your Kubernetes Deployments are synced with your Kubernetes Stacks, and pull requests show you a preview of what they’re planning to change. 

To take this one step further, you could add custom policies to reinforce the security and reliability of your configurations and deployments. Spacelift provides different types of policies and workflows that are easily customizable to fit every use case. For instance, you could add plan policies to restrict or warn about security or compliance violations or approval policies to add an approval step during deployments. 

You can try Spacelift for free by creating a trial account or booking a demo with one of our engineers.

We’ve explored the features and benefits of K3s, a certified Kubernetes distribution designed to be portable, versatile, and easy to use. Whether you need to run Kubernetes locally or are planning a new IoT fleet deployment, K3s can provide a stable foundation for your cluster.

Scenarios where K3s is less useful include when your workloads are cloud-centric and you’re seeking a declarative infrastructure and configuration management strategy. 

Choosing a managed cloud K8s service such as Amazon EKS or Google GKE could be a more effective choice as this allows you to use IaC tools and an orchestration platform like Spacelift to fully automate your cluster provisioning workflow.