I am trying to start a Debian image with the /sbin/init process for ansible role testing via molecule.
Yes, I am aware, that one should not start /sbin/init in a container unless you really have a use case for doing so. With molecule I can test my ansible roles in a docker container. As such I need /sbin/init running.
When I execute
docker run -it --privileged -v /sys/fs/cgroup:/sys/fs/cgroup:ro debian:9 /sbin/init
docker: Error response from daemon: OCI runtime create failed: container_linux.go:346:
starting container process caused "exec: \"/sbin/init\": stat /sbin/init: no such file
or directory": unknown.
However, with debian:8 it works just fine.
docker run -it --privileged -v /sys/fs/cgroup:/sys/fs/cgroup:ro debian:8 /sbin/init
works like a charm.
Has Debian switched to a new boot process? What changed?
Turns out Debian has removed the init package from their docker images starting with debian:9 and newer.
That is great since it helps all of us to fail early/fast. We really should not start /sbin/init unless we have a use-case for doing so - and believe me, most of the time we do not.
So what to do if we really have a use-case in which we need to run /sbin/init?
Well, we can install it via
apt-get install -y init
If you need a Dockerfile for that
FROM debian:9
RUN apt-get update && apt-get install -y init && apt-get clean all