Network bridge of unknown origin

Networking
,
1

I recently changed my VM networking from NAT to bridge, and whilst I was bumbling around in the dark trying to learn enough to get that going I came across a bridge of unknown origin:

rodney@hex:~$ sudo brctl show
bridge name	bridge id		            STP enabled	interfaces
br-7578bf695087     8000.024271455d2f	no		    veth3de0c64
						                            veth8446113
						                            vethdb1b749
br0		            8000.b42e99372b89	no		    eno1
docker0		        8000.024263f71e59	no

How do I go about determining who created the first bridge? I am pretty sure its got to be libvirt, as it does not appear in my list of docker networks:

rodney@hex:~$ sudo docker network ls
NETWORK ID     NAME                DRIVER    SCOPE
6e28c36295ad   bridge              bridge    local
7578bf695087   documents_default   bridge    local
0855d74822eb   host                host      local
f3f7df40b88a   none                null      local

As far as I can tell, this bridge does nothing useful, so I would like to get rid of it if I can. I have tried using brctl to remove it, but the darn thing keeps coming back.

EDIT

Unbelievable. No sooner do I post than I realise that the 7578bf695087 portion of the bridge name does appear in the list of docker networks, ie br-7578bf695087. So I guess that answers that question.

2

In my system, a bridge named similarly to your br-7578bf695087 is generated as the default bridge for the docker containers instantiated via docker-compose. docker0 is the default used by containers instantiated by docker run.

You can use docker network ls to see more about these.

Also, check this:

3

Indeed. It turns out that when you use docker-compose, it creates a bridge whose name includes the directory from whence the yml file was run. In my case this bridge is called documents_default, and it has an ID of br-7578bf695087.

In hindsight it should have been obvious that docker originated the bridge, but at the time I was not aware that you could inspect docker networks as you described. Once I saw the configuration of the bridge, all became clear. At least I learned something!