K3S¶

Lightweight Kubernetes. Production ready, easy to install, half the memory, all in a binary less than 100 MB.

Project Homepage: K3s.io Documentation: K3s Documentation

Installation¶

To install k3s, you can follow different approaches like setting up k3s with an external database, embedded database, or as a single node.

K3s with external DB¶

Set up an HA K3s cluster backed by an external datastore such as MySQL, PostgreSQL, or etcd.

Install Database¶

Install MariaDB.

Install Servers¶

curl -sfL https://get.k3s.io | sh -s - server \
--token=YOUR-SECRET \
--datastore-endpoint='mysql://user:pass@tcp(ipaddress:3306)/dbname' \
--node-taint CriticalAddonsOnly=true:NoExecute \
--tls-san your-dns-name --tls-san your-lb-ip-address

Node-Taint¶

By default, server nodes will be schedulable and thus your workloads can get launched on them. If you wish to have a dedicated control plane where no user workloads will run, you can use taints. The node-taint parameter will allow you to configure nodes with taints, for example --node-taint CriticalAddonsOnly=true:NoExecute.

SSL Certificates¶

To avoid certificate errors in such a configuration, you should install the server with the --tls-san YOUR_IP_OR_HOSTNAME_HERE option. This option adds an additional hostname or IP as a Subject Alternative Name in the TLS cert, and it can be specified multiple times if you would like to access via both the IP and the hostname.

Get a registered Address¶

TODO: WIP

Install Agents¶

TODO: WIP

curl -sfL https://get.k3s.io | sh -s - agent \
--server https://your-lb-ip-address:6443 \
--token YOUR-SECRET

K3s with embedded DB¶

Set up an HA K3s cluster that leverages a built-in distributed database.

TODO: WIP

Install first Server¶

TODO: WIP

curl -sfL https://get.k3s.io | sh -s - server \
--token=YOUR-SECRET \
--tls-san your-dns-name --tls-san your-lb-ip-address \
--cluster-init

To avoid certificate errors in such a configuration, you should install the server with the --tls-san YOUR_IP_OR_HOSTNAME_HERE option. This option adds an additional hostname or IP as a Subject Alternative Name in the TLS cert, and it can be specified multiple times if you would like to access via both the IP and the hostname.

Install additional Servers¶

TODO: WIP

curl -sfL https://get.k3s.io | sh -s - server \
--token=YOUR-SECRET \
--tls-san your-dns-name --tls-san your-lb-ip-address \
--server https://IP-OF-THE-FIRST-SERVER:6443

The --cluster-init initializes an HA Cluster with an embedded etcd database. The fault tolerance requires an odd number, minimum three, nodes to function.

Total Number of nodes	Failed Node Tolerance
1	0
2	0
3	1
4	1
5	2
6	2
...	...

Get a registered Address¶

To achieve a high-available scenario you also need to load balance incoming connections between the server nodes.

TODO: WIP

Install Agents¶

You can still add additional nodes without a server function to this cluster.

curl -sfL https://get.k3s.io | sh -s - agent \
--server https://your-lb-ip-address:6443 \
--token YOUR-SECRET

K3s single node¶

Set up K3s as a single node installation.

TODO: WIP

Manage K3S¶

Management on Server Nodes¶

k3s kubectl

Download Kube Config¶

/etc/rancher/k3s/k3s.yaml

Database Backups¶

etcd snapshots¶

Stored in /var/lib/rancher/k3s/server/db/snapshots.