Hi Folks,
When the host OS is Ubuntu 16.04 or RHEL 7.x, the following command is
working, helping us to run systemctl commands on the host from within the
docker container:
# nsenter --mount=/hostroot/proc/1/ns/mnt -- systemctl start dummy.service
But in the newer host OS-es, Ubuntu 20.04 and RHEL 8.x, this doesn't work
and we get the following error:
# nsenter --mount=/hostroot/proc/1/ns/mnt -- systemctl start dummy.service
Failed to connect to bus: No data available
I have attached a minimalistic example and commands to run and reproduce
the issue:
Sample service which I wanted to start on the host, from the container:
# cat /etc/systemd/system/dummy.service
[Unit]
Description=dummy service
[Service]
ExecStart=/usr/bin/sleep infinity
Dockerfile of my container:
# cat Dockerfile
FROM ubuntu:20.04
ENV TZ=UTC
RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ >
/etc/timezone
RUN apt update -y --fix-missing
RUN apt install -y util-linux
STOPSIGNAL SIGRTMIN+3
CMD [ "/bin/bash" ]
Build the image:
# docker build -t trial .
Delete any stale containers:
# docker rm -f trial
Run the image:
# docker run -it -d --net=host --privileged -v /:/hostroot -v
/sys/fs/cgroup:/sys/fs/cgroup:ro --name trial trial
Reproduce the issue:
# docker exec -it trial bash
# nsenter --mount=/hostroot/proc/1/ns/mnt -- systemctl start dummy.service
Failed to connect to bus: No data available
I would like to know if there are any additional options or any docker run
command that needs to be altered to get this working.
Regards,
Aravindhan Krishnan...
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