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Merge pull request #2201 from galal-hussein/sizing_guide

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Add sizing guide
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Catherine Luse
2020-02-28 10:16:32 -07:00
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commit 51981b8df1
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content/k3s/latest/en/installation/node-requirements/_index.md → content/k3s/latest/en/installation/installation-requirements/_index.md
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@@ -1,5 +1,5 @@
---
title: Node Requirements
title: Installation Requirements
weight: 1
---
@@ -8,6 +8,7 @@ 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.
## Prerequisites
* Two nodes cannot have the same hostname. If all your nodes have the same hostname, pass `--node-name` or set `$K3S_NODE_NAME` with a unique name for each node you add to the cluster.
## Operating Systems
@@ -33,8 +34,37 @@ K3s performance depends on the performance of the database. To ensure optimal sp
## Networking
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.
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.
## Large Clusters
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:
- MySQL
- PostgreSQL
- etcd
### CPU and Memory
The following are the minimum CPU and memory requirements for nodes in a high-availability K3s server:
| Deployment Size | Nodes | VCPUS | RAM |
|:---------------:|:---------:|:-----:|:-----:|
| Small | Up to 10 | 2 | 4 GB |
| Medium | Up to 100 | 4 | 8 GB |
| Large | Up to 250 | 8 | 16 GB |
| X-Large | Up to 500 | 16 | 32 GB |
| XX-Large | 500+ | 32 | 64 GB |
### Disks
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.
### Network
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.