Raspberry Pi k3s fleet — network and power prerequisites¶
Parent runbook: How to provision k3s, Longhorn, and Rancher on a Raspberry Pi fleet.
Network — mandatory¶
- Stable L2/L3 connectivity between all cluster nodes (same site for P0/P1 unless you are explicitly building multi-site later).
- Reserved IPs or DHCP reservations; document hostname or IP used in
K3S_URL. - DNS or
/etc/hostsconsistency for TLS names (Rancher, ingress, Longhorn UI if exposed). - Firewall rules documented per k3s networking requirements at install time.
- Time sync available (internet NTP or local stratum server).
Optional (HA / scale)¶
- Secondary uplink or out-of-band way to power-cycle remote Pis (no IPMI on Pi—plan smart PDU or on-site access).
- Site-to-site VPN only when multi-site etcd or storage replication is explicitly architected (later).
Power — mandatory for P1+¶
| Requirement | Why |
|---|---|
| Clean shutdown budget | etcd and Longhorn dislike unclean power loss during writes. |
| Known brownout behavior | UPS or generator discipline at farm edge—Off-grid power strategy — Demory. |
| Labeled circuits | Partial cluster power loss produces confusing storage quorum symptoms. |
Optional (HA / scale)¶
- UPS feeding switch and core Pis together so the network does not die while nodes stay up.
Farm / off-grid coupling (context)¶
mermaid
flowchart LR
subgraph util [Utility]
Grid[Grid / inverter]
Batt[Battery]
end
subgraph net [Cluster LAN]
K[k3s nodes]
Sw[Switch]
end
Grid --> Batt
Batt --> K
Grid --> Sw
If optional farm power (Popt) cannot sustain cluster plus network baseline load, do not claim a tight P1 RTO: run fewer stateful sets or shut down gracefully before the battery floor. Align with Off-grid operational decision rules — power and networking (Demory) when those constraints apply.