Illumina Innovates with Rancher and Kubernetes
K3s is very lightweight, but has some minimum requirements as outlined below.
Whether you’re configuring a K3s cluster to run in a Docker or Kubernetes setup, each node running K3s should meet the following minimum requirements. You may need more resources to fit your needs.
K3s should run on just about any flavor of Linux. However, K3s is tested on the following operating systems and their subsequent non-major releases.
If you are using Raspbian Buster, follow these steps to switch to legacy iptables.
If you are using Alpine Linux, follow these steps for additional setup.
Hardware requirements scale based on the size of your deployments. Minimum recommendations are outlined here.
K3s performance depends on the performance of the database. To ensure optimal speed, we recommend using an SSD when possible. Disk performance will vary on ARM devices utilizing an SD card or eMMC.
The K3s server needs port 6443 to be accessible by the nodes. The nodes need to be able to reach other nodes over UDP port 8472 (Flannel VXLAN). If you do not use Flannel and provide your own custom CNI, then port 8472 is not needed by K3s. The node should not listen on any other port. K3s uses reverse tunneling such that the nodes make outbound connections to the server and all kubelet traffic runs through that tunnel.
IMPORTANT: The VXLAN port on nodes should not be exposed to the world as it opens up your cluster network to be accessed by anyone. Run your nodes behind a firewall/security group that disabled access to port 8472.
If you wish to utilize the metrics server, you will need to open port 10250 on each node.
Hardware requirements are based on the size of your K3s cluster. For production and large clusters, we recommend using a high-availability setup with an external database. The following options are recommended for the external database in production:
The following are the minimum CPU and memory requirements for nodes in a high-availability K3s server:
The cluster performance depends on database performance. To ensure optimal speed, we recommend always using SSD disks to back your K3s cluster. On cloud providers, you will also want to use the minimum size that allows the maximum IOPS.
You should consider increasing the subnet size for the cluster CIDR so that you don’t run out of IPs for the pods. You can do that by passing the --cluster-cidr option to K3s server upon starting.
K3s supports different databases including MySQL, PostgreSQL, MariaDB, and etcd, the following is a sizing guide for the database resources you need to run large clusters: