I'm trying to use the systemctl command in a ubuntu:16.04 docker container. I'm running the following command...
systemctl status ssh
However I'm getting the error...
Failed to connect to bus: No such file or directory
Why is this not working? Is this related to Ubuntu running in a docker container? How can I get systemctl to work correctly?
I assume you start your docker container with something like
docker run -t -i ubuntu:16.04 /bin/bash
The problem now is that your init process PID 1 is /bin/bash, not systemd.
Confirm with ps aux.
In addition to that you are missing dbus, which would be the way to communicate. This is where your error message is coming from. But as your PID 1 is not systemd, it will not help to install dbus.
Best would be to re-think the way you plan to use docker. Do not rely on systemd as a process manager but have the docker container run your desired application in the foreground.
Others have reported a similar problem. Start up the terminal and type:
$ env
Do you see an environment variable like this?
XDG_RUNTIME_DIR=/run/user/`id -u`
Where id -u is enclosed in backticks not single quotes. This variable is reinterpreted into a number usually 1000 for regular users and 0 for super user (sudo).
If the environment variable XDG_RUNTIME_DIR does not exist you need to create it. The full discussion is in launchpad systemd answers.
If you're getting this error in the Windows Subsystem for Linux (WSL), I've found it's because Docker is unsupported. This is due to lack of cgroups and other prerequisites.
Try this:
docker run -ti -d --privileged=true images_docker "/sbin/init"
or
docker run -ti -d --privileged=true images_docker
will be same result.
Here I get from the doc of Docker:
By default, Docker containers are “unprivileged” and cannot, for example, run a Docker daemon inside a Docker container. This is because by default a container is not allowed to access any devices, but a “privileged” container is given access to all devices (see the documentation on cgroups devices).
When the operator executes docker run --privileged, Docker will enable access to all devices on the host as well as set some configuration in AppArmor or SELinux to allow the container nearly all the same access to the host as processes running outside containers on the host. Additional information about running with --privileged is available on the Docker Blog.
You may not be running systemd, which is the default implementation of init on 16.04. If you upgraded from 14.04, you are most likely still running upstart, and the result of running the systemctl command is the output you got.
See my answer at systemctl : comand not found 16.04 server for more.
I was getting the exact same error and then I run it successfully with sudo
sudo systemctl status ssh
Inside docker container, I think you can update-rc.d if you are still struggling with systemd. I tried with update-rd.c and it works.
