Restart ModemManager from container

Product support balenaOS
#1

Hi,

I need to restart the HostOS’s systemd service ModemManager from a container.
Running systemctl restart ModemManager.service from hostOS works fine but I cannot do that from the container.

I have dbus configured in the docker files and mmcli works in the container.

How can I do this?

Thanks in advance

#3

I used the D-Bus socket to restart a host systemd service from a container. Maybe there is a cleaner way of doing it, but for me, this works good enough.

If you mount the D-Bus socket into your container with a bind mount when you start your container using the following:

-v /var/run/dbus/system_bus_socket:/var/run/dbus/system_bus_socket

You can then use the dbus-send command-line tool that comes with dbus from within the container to talk to systemd on the host OS via the D-Bus socket that you mounted.

I created a bash function that accepts the name of the service you want to restart.

dbus_restart_service () {
  dbus-send --system --print-reply=literal \
    --dest=org.freedesktop.systemd1 \
    /org/freedesktop/systemd1 \
    org.freedesktop.systemd1.Manager.RestartUnit \
    string:"$1" \
    string:"replace"
}

You would use the function like this:

dbus_restart_service "ModemManager.service"

1 Like
#4

Thanks but the command you sent seems incomplete, did you miss out something in the beginning?
Thanks

#5

Hopefully my edited reply is of use to you.

#6

Thanks the function worked perfectly!