SmolBSD – build your own minimal BSD system

3 weeks ago 1

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build your own minimal BSD UNIX system

About

smolBSD is a meta-operating system built on top of NetBSD. It lets you compose your own UNIX environment — from a single-purpose microservice system to a fully-custom OS image — in just a few minutes.

The smolBSD environment uses the netbsd-MICROVM kernel as its foundation, leveraging the same portable, reliable codebase that powers NetBSD itself. You decide what to include — sshd, httpd, or your own service — and smolBSD builds a coherent, minimal, bootable image ready to run anywhere.

$ bmake SERVICE=bozohttpd build ➡️ starting the builder microvm ➡️ host filesystem mounted on /mnt ➡️ fetching sets ➡️ creating root filesystem (512M) done ✅ image ready: bozohttpd-amd64.img

Why smolBSD

Build BSD systems like you build software — fast, reproducible, and minimal.

🧩 Composable

Pick only the components you need — from kernel to services.

⚙️ Reproducible

Every build is deterministic, portable, and easy to version-control.

🚀 Instant Boot

💻 Universal

Runs anywhere QEMU or Firecracker runs — cloud, CI, edge, or laptop.

Quick Start

Build and boot your own BSD system in seconds:

$ git clone https://github.com/NetBSDfr/smolBSD $ cd smolBSD $ bmake SERVICE=sshd build ➡️ starting the builder microvm ➡️ fetching sets ➡️ creating root filesystem (512M) done ✅ image ready: sshd-amd64.img ➡️ killing the builder microvm $ ./startnb.sh -f etc/sshd.conf [ 1.0092096] kernel boot time: 14ms Starting sshd. Server listening on :: port 22. Server listening on 0.0.0.0 port 22. Download

Examples

bozohttpd

A complete static web server in a few megabytes. smolBSD builds a minimal system with bozohttpd preconfigured and ready to serve content immediately on boot.

$ bmake SERVICE=bozohttpd build ➡️ starting the builder microvm ➡️ fetching sets ➡️ creating root filesystem (512M) done ✅ image ready: bozohttpd-amd64.img $ ./startnb.sh -f etc/bozohttpd.conf [ 1.001231] kernel boot time: 10ms Starting bozohttpd on :80 listening on 0.0.0.0:80

nbakery

A lightweight build and image creation service based entirely on NetBSD tools. The nbakery image gives you a taste of a preconfigured NetBSD environment with all the well known tools.

$ bmake SERVICE=nbakery build ➡️ starting the builder microvm ➡️ fetching sets ➡️ creating root filesystem (512M) done ✅ image ready: nbakery-amd64.img $ ./startnb.sh -f etc/nbakery.conf [ 1.008374] kernel boot time: 11ms Welcome to the (n)bakery! 🧁 💪 doas to run command as root 📦 pkgin to manage packages 🚪 exit to cleanly shutdown, ^a-x to exit qemu 🪟 you are inside a tmux with prefix ^q

nitrosshd

A minimal secure shell server started with nitro, designed to launch instantly and provide remote access with zero unnecessary services. Ideal for an SSH bouncer.

$ bmake SERVICE=nitrosshd build ➡️ starting the builder microvm ➡️ fetching sets ➡️ creating root filesystem (512M) done ✅ image ready: nitrosshd-amd64.img $ ./startnb.sh -f etc/sshd.conf [ 1.011598] kernel boot time: 12ms Created tmpfs /dev (1835008 byte, 3552 inodes) Starting sshd. Server listening on :: port 22. Server listening on 0.0.0.0 port 22.

Community

smolBSD is an independent project built on top of NetBSD. Join us, share your micro-systems, or contribute new services and build recipes.

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