Add systemd support for container

[praveenkumar]

If the container have entrypoint of /sbin/init it just hangs there.

[crosbymichael]

What image are you using to reproduce this issue?

[afbjorklund]

What image are you using to reproduce this issue?

You can use either kind or minikube images, for instance.

ARG BASE_IMAGE=debian:bookworm-slim
FROM $BASE_IMAGE AS base

ENTRYPOINT [ "/usr/local/bin/entrypoint", "/sbin/init" ]

ARG UBUNTU_JAMMY_IMAGE="ubuntu:jammy-20250415.1"
FROM ${UBUNTU_JAMMY_IMAGE} as kicbase

ENTRYPOINT [ "/usr/local/bin/entrypoint", "/sbin/init" ]

Any image that tries uses systemd as init should be enough, since it does seems to work* with openrc as init.

1. /sbin/init -> /lib/systemd/systemd (e.g. ubuntu)

FROM ubuntu
RUN apt-get update && apt-get install -y systemd-sysv && rm -rf /var/lib/apt/lists/*

ENTRYPOINT ["/sbin/init"]

2. /sbin/init -> /bin/busybox (e.g. alpine)

FROM alpine
RUN apk add openrc

ENTRYPOINT ["/sbin/init"]

---

* Where "work" means that there is some duplication between vminitd and the openrc /etc/init.d scripts.

For instance they both try to mount the devices, and some other early boot features for the virtual machine.