DIY Mini-Supercomputer — Khalid Alnujaidi

Background

Most of us have a drawer or shelf of machines that are too good to throw away and too slow to use alone — a retired work laptop, a mini-PC, an old desktop. Individually they're e-waste in waiting. Pooled together, they're a genuinely useful private cloud.

The goal was a single, reusable provisioning artifact: build one USB stick, then provision any number of machines with it — no per-device clicking through installers, no bespoke setup. Flash once, reuse forever. The result is a self-serve way to turn heterogeneous, recycled hardware into a single Kubernetes cluster you control from anywhere.

How it works

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One reusable image

The official Ubuntu 24.04 ISO is remastered (xorriso) into an unattended autoinstall image. Every machine installs itself identically, zero prompts.

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Fully offline install

The OS install needs no network at all. Anything network-dependent is deferred to first boot, so even Wi-Fi-only laptops provision cleanly.

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Tailscale mesh

Each node auto-joins a private mesh VPN on boot with a baked auth key, so it's reachable at a stable address regardless of flaky home networking.

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One-command join

A fresh node becomes a cluster member with a single k3s-join nodeN — which also names the node and wires it to the control-plane.

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Clone-safe identity

Fresh machine-id on every shutdown, unique throwaway hostnames, DHCP instead of baked static IPs — so the same image never collides across machines.

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Laptops welcome

Wi-Fi credentials baked in (2.4 + 5 GHz), lid-close suspend disabled — so an old laptop runs happily as a headless server node.

Built with

k3s (Kubernetes) Ubuntu 24.04 autoinstall cloud-init xorriso Tailscale netplan systemd Bash

The cluster it built

52 vCPUs pooled

82 GB RAM

3.2 TB storage

4 nodes, 1 cluster

A Ryzen 7 9700X workstation as the control-plane, three Intel i5 mini-PCs as workers — all stitched into one k3s cluster over Tailscale, each one provisioned from the same USB stick in minutes. Adding the next machine is now trivial: flash, boot, join.

Why it matters

Beyond the compute, the project is a template for sustainable hardware reuse: a documented, reproducible path from a pile of mismatched, retired machines to a working private cluster — using only free tools and a weekend. The full build, including every bug fought and fixed along the way, is written up as an open guide for anyone to follow.

So — how much can you recover?

Go count the machines gathering dust: the laptop with the tired battery, the pre-pandemic desktop, the mini-PC you forgot you owned, that Raspberry Pi in a drawer. Every one of them is idle compute you already paid for. Flash one USB, boot them, join them, and watch a free cluster grow out of your junk drawer. What can you bring back to life?