pi-swarm/docs/PLAN.md

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

• 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).