2.5 KiB
2 Node HA Control Plane with external database
For this configuration we are deploying a highly available control plane composed of two control nodes. This can be achieved with embedded etcd, however etcd ideally has an odd number of nodes.
The example below will use an external PostgreSQL datastore to store the cluster state information.
Main guide: https://rancher.com/docs/k3s/latest/en/installation/ha/
Architecture
+-------------------+
| Load Balancer/VIP |
+---------+---------+
|
|
|
|
+------------+ | +------------+
| | | | |
+--------+ control-01 +<-----+----->+ control-02 |
| | | | |
| +-----+------+ +------+-----+
| | |
| +-------------+-------------+
| | | |
| +------v----+ +-----v-----+ +----v------+
| | | | | | |
| | worker-01 | | worker-02 | | worker-03 |
| | | | | | |
| +-----------+ +-----------+ +-----------+
|
| +-------+ +-------+
| | | | |
+-------------------> db-01 +--+ db-02 |
| | | |
+-------+ +-------+
Required Components
- Load balancer
- 2 control plane nodes
- 1 or more worker nodes
- PostgreSQL Database (replicated, or Linux HA Cluster).
Configuration
For your control nodes, you will need to instruct the control plane of the
PostgreSQL datastore endpoint and set k3s_registration_address to be the
hostname or IP of your load balancer or VIP.
Below is the example for PostgreSQL, it is possible to use MySQL or an Etcd cluster as well. Consult the below guide for using alternative datastore endpoints.
---
k3s_server:
datastore-endpoint: postgres://postgres:verybadpass@database:5432/postgres?sslmode=disable
node-taint:
- "k3s-controlplane=true:NoExecute"
Your worker nodes need to know how to connect to the control plane, this is
defined by setting k3s_registration_address to the hostname or IP address of
the load balancer.
---
k3s_registration_address: control.examplek3s.com