Unable to run systemctl command from Centos8 Container-CodePudding

I am trying to install and run an apache installation on a centos8 image. I had pulled the roboxes/centos8 image and spun up a container. Now, when I run the yum install httpd -y, success. However, when I try to run

[root@c46ad701eed2 /]# systemctl status httpd
System has not been booted with systemd as init system (PID 1). Can't operate.
Failed to connect to bus: Host is down
[root@c46ad701eed2 /]#

any insight into how to fix this is much appreciated in advance. Tried digging around and found some instructions to start in a privileged mode. However, as per my understanding, running in a privileged mode compromises the security of the root system.

Thanks

CodePudding user response：

Create a Dockerfile as below:

FROM roboxes/centos8
MAINTAINER arrzion-data-systems <[email protected]>
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 -y install httpd
RUN yum clean all
RUN systemctl enable httpd.service
VOLUME [ "/sys/fs/cgroup" ]
EXPOSE 80 8080
CMD ["/usr/sbin/init"]

To Build the Image:

docker build --rm -t centos8/systemd .

Next Run:

docker run -ti --tmpfs /tmp --tmpfs /run -v /sys/fs/cgroup:/sys/fs/cgroup:ro -p 80:80 centos8/systemd

The above solution was extracted from the link: Docker (CentOS 7 with SYSTEMCTL) : Failed to mount tmpfs & cgroup

Solutions to

Issue 1:

[root@c46ad701eed2 /]# systemctl status httpd
System has not been booted with systemd as init system (PID 1). Can't operate.
Failed to connect to bus: Host is down

Issue 2:

# docker run -ti -v /sys/fs/cgroup:/sys/fs/cgroup:ro -p 80:80 centos8/systemd
Failed to mount tmpfs at /run: Operation not permitted
Failed to mount cgroup at /sys/fs/cgroup/systemd: Operation not permitted
[!!!!!!] Failed to mount API filesystems, freezing.

Issue 3:

Failed to get D-Bus connection: Operation not permitted

This is pretty much a concise solution for all the above issues and systemctl also working fine.

One issue though, Filesystem Space and Memory usage has spiked with this method.

CodePudding user response：

The right answer to your question was posted by David Maze in the comment:

To a first approximation systemctl just doesn't work in Docker, and it's not appropriate to try to run systemd in a container. Whatever the container's main process is should get run as a foreground process, like apachectl -DFOREGROUND; or better still, run the Docker Hub httpd image.