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