Docker: error when running init and systemctl in shell script for CMD

Question

Dockerfile

# Use Centos7 or RHEL7 base image
FROM centos:7

# This steps are needed so that systemd works within container
#ENV container docker

RUN (cd /lib/systemd/system/sysinit.target.wants/; for i in *; do [ $i == \
systemd-tmpfiles-setup.service ] || rm -f $i; done); \
rm -f /lib/systemd/system/multi-user.target.wants/*;\
rm -f /etc/systemd/system/*.wants/*;\
rm -f /lib/systemd/system/local-fs.target.wants/*; \
rm -f /lib/systemd/system/sockets.target.wants/*udev*; \
rm -f /lib/systemd/system/sockets.target.wants/*initctl*; \
rm -f /lib/systemd/system/basic.target.wants/*;\
rm -f /lib/systemd/system/anaconda.target.wants/*;

COPY startup.sh /usr/local/bin/startup.sh
CMD ["/usr/sbin/init"]

startup.sh

#!/bin/bash
systemctl restart autofs

Now, I can run the following without a problem

docker build -t mycentos
docker run -d --privileged --name mycentos mycentos
docker exec -it  mycentos /bin/bash
./usr/local/bin/startup.sh

I would like that startup.sh to run automatically without me having to go into a container and run it manually

So, I just rolled /usr/sbin/init into startup.sh and changed Dockerfile CMD

CMD ["/usr/local/bin/startup.sh"]

and

startup.sh is now

#!/bin/bash
/usr/sbin/init
systemctl restart autofs

I am getting the error

Couldn't find an alternative telinit implementation to spawn.
Failed to get D-Bus connection: Operation not permitted

Any idea how to get startup.sh to work?

PS I remember seeing the same error message when /usr/sbin/init was not running and i treid to run systemctl

EDIT I've changed startup.sh

#!/bin/bash
/usr/bin/systemctl restart autofs &
exec /usr/sbin/init

And it looks like autofs is never started from "docker run" CMD

$docker run --rm -itd --privileged --name mycentos mycentos
0c977e677897fc9a42bd3a4efe6742fbb14ed888a010cfee94c604436729db2d
$ docker exec -it mycentos /bin/bash
[root@0c977e677897 /]# systemctl status autofs
\u25cf autofs.service - Automounts filesystems on demand
   Loaded: loaded (/usr/lib/systemd/system/autofs.service; disabled; vendor preset: disabled)
   Active: inactive (dead)

Answer 1

As you did not install autofs and the 2nd thing you did not enable it in docker file. you to enable it in Dockerfile first.

Here is your Dockerfile with a bit modification and the startup script as same as your updated one.

startup.sh

 #!/bin/bash
/usr/bin/systemctl restart autofs &
exec /usr/sbin/init

Dockerfile

 FROM centos:7

# This steps are needed so that systemd works within container
#ENV container docker

RUN (cd /lib/systemd/system/sysinit.target.wants/; for i in *; do [ $i == \
systemd-tmpfiles-setup.service ] || rm -f $i; done); \
rm -f /lib/systemd/system/multi-user.target.wants/*;\
rm -f /etc/systemd/system/*.wants/*;\
rm -f /lib/systemd/system/local-fs.target.wants/*; \
rm -f /lib/systemd/system/sockets.target.wants/*udev*; \
rm -f /lib/systemd/system/sockets.target.wants/*initctl*; \
rm -f /lib/systemd/system/basic.target.wants/*;\
rm -f /lib/systemd/system/anaconda.target.wants/*;
RUN yum install -y autofs
COPY startup.sh /usr/local/bin/startup.sh
RUN chmod +x /usr/local/bin/startup.sh
RUN systemctl enable autofs
CMD ["/usr/local/bin/startup.sh"]

NOTE: This also sometimes needs to mount cgroup for systemctl.

-v /sys/fs/cgroup:/sys/fs/cgroup:ro 

Here run the command in a docker container

For further information, you can check this GitHub.

https://github.com/whyistheinternetbroken/docker-centos7-nfs-client-autofs/blob/master/Dockerfile