Initial inventory and rebuild plan for planck cluster

docs/PLAN.md

@@ -0,0 +1,50 @@
+# Rebuild plan & decisions log
+
+## Where we started (2026-09-19)
+
+- Old cluster: Docker Swarm (manager planck001) with Portainer, Traefik, and
+  what appears to be CapRover remnants. Broken: workers stuck in "pending"
+  because the manager's IP changed (workers dial stale `192.168.1.173:2377`).
+- Decision: **wipe everything and rebuild clean** rather than repair.
+
+## Hardware
+
+- 20× Raspberry Pi 4 Model B Rev 1.4, 8GB RAM, 4 cores
+- Boot: 238.5GB USB SSD on every node (no SD cards installed)
+- Bootloader EEPROM: 2023/01/11 on 19 nodes; planck019 has Feb 2021 (update it)
+- All nodes healthy: temps 43–52°C, disks ~4% used
+
+## Network
+
+- Ubiquiti UDM Pro, 2 switches, all nodes on the same router
+- IPs currently drift across 192.168.0/1/2.x subnets via DHCP — planck001 sits
+  on 192.168.30.x (different subnet, cause unknown, doesn't matter: we're
+  rebuilding)
+- Decision: **dedicated static addressing for the cluster** via UniFi DHCP
+  reservations (MAC table in `docs/MACS.txt`)
+
+## Storage
+
+- Synology NAS on same LAN — shared storage target (NFS) for cluster
+  workloads
+
+## Phases
+
+- [x] Phase 0 — Access + inventory (SSH keys on all 20, docs/)
+- [ ] Phase 1 — Network design: static IPs / reservations in UniFi
+- [ ] Phase 2 — Reimage all 20 nodes with fresh Raspberry Pi OS
+- [ ] Phase 3 — Cluster runtime install (candidates: k3s vs Docker Swarm)
+- [ ] Phase 4 — Storage integration with Synology (NFS CSI)
+- [ ] Phase 5 — Apps: monitoring, Portainer/UI, whatever the lab is for
+
+## Open decisions
+
+1. **Reimage method** — options:
+   a. PXE/network boot: EEPROM boot-order set to netboot; DHCP next-server
+      points at a TFTP/HTTP installer. Zero-touch per node, reusable forever.
+      Installer server can run on the Synology (Docker) or a laptop.
+   b. SD-card bootstrap installer: flash one SD image, insert per node, it
+      wipes + installs the USB SSD, removes itself. Simple, physical walk.
+   c. Pull SSDs, image on a PC with Raspberry Pi Imager ×20. Most manual.
+2. **Cluster runtime** — k3s (lighter, k8s-compatible, we manage it with
+   automation) vs Docker Swarm + Portainer (simplest).