Booting under systemd

By default the microsandbox agent is PID 1. That’s enough for one-shot processes, but anything that calls into systemctl, loginctl, or expects a session bus will fail. --init auto hands PID 1 over to systemd. The rest of the guest then behaves like a normal Linux box.

Step 1: Boot

msb run ghcr.io/superradcompany/debian-systemd:12 \
  --memory 1G --cpus 2 \
  --init auto \
  -- bash

debian-systemd is one of the optional bases we maintain in guest-images for cases like this. --init auto uses a known init from the image ENTRYPOINT when one is declared, then falls back to probing common distro paths. Image-declared /init wrappers keep their OCI launch contract for attached msb run; bare systemd images still run your trailing command through agentd after boot. See Custom init system for the exact behavior and for pinning to an explicit path.

Step 2: Confirm systemd is PID 1

root@msb:/# systemctl status
● msb
    State: running
    Units: 113 loaded (incl. loaded aliases)
  systemd: 252.39-1~deb12u1

Or check directly:

root@msb:/# cat /proc/1/comm
systemd

Step 3: Manage units

systemctl works as it does on bare metal. Inspect a unit shipped with the image:

root@msb:/# systemctl status systemd-journald
● systemd-journald.service - Journal Service
     Loaded: loaded (/lib/systemd/system/systemd-journald.service; static)
     Active: active (running)

Install your own and start it:

root@msb:/# apt update && apt install -y nginx
root@msb:/# systemctl enable --now nginx
root@msb:/# curl -s localhost | head -1
<!DOCTYPE html>

The guest detects microsandbox as a container, so packages with policy-rc.d deferral install but don’t auto-start. systemctl enable --now <unit> starts them in one step.

Notes

Image choice matters. Distroless / minimal images (python:3.13-slim, alpine) don’t ship a systemd init binary; --init auto will fail if it cannot resolve a known image ENTRYPOINT init or find a guest-side probe match. Use a systemd-equipped base or layer one in.
Memory budget. systemd’s idle footprint is ~50 MiB; daemons add more. Bump --memory if your service is hungry.
Other inits work. --init accepts any absolute path. s6, OpenRC, runit, or a hand-rolled /sbin/init shell script are all fine; auto covers known image ENTRYPOINT inits plus common distro init paths.

Docker

Guest

Metrics backends

Step 1: Boot

Step 2: Confirm systemd is PID 1

Step 3: Manage units

Notes

​Step 1: Boot

​Step 2: Confirm systemd is PID 1

​Step 3: Manage units

​Notes

Step 1: Boot

Step 2: Confirm systemd is PID 1

Step 3: Manage units

Notes