[lxc-users] Need help with static IP address -- Simplest use case.

[Fajar A. Nugraha]

On Sat, Jun 10, 2017 at 12:38 PM, Michael Johnson <johnson at cognitech-ut.com>
wrote:

> Thanks for all the suggestions. I seem to have magically fixed it. When
> I changed the parent from lxdbr0 to br0 it now works. Lxdbr0 was a
> 'network' I created with 'lxc network create' and br0 was the host
> bridge I configured by hand. This probably makes sense to someone who
> understands how lxd works. There seems to be a conflict between static
> ip addresses and the way 'lxc network create' defines a bridge. Possibly
> I missed a config option for routing that is necessary when static ip is
> combined with 'lxc network create'.
>
>

You seem misunderstood some concept:

(1) lxc network create
- basically creates a bridge, managed by lxd, optionally with its own DHCP
server (dnsmasq).
- it is a SEPARATE network from your host's network (e.g. eth0)
- you CAN assign "static ip" on this bridge. Or to be more accurate,
configure the dhcp server to always assign a specific IP for that container

(2) host bridge (should be br0 in your example)
- on the same L2 network with your host interface
- use whatever DHCP server available on the network (if available). You
should NOT create your own dhcp server on this bridge

(3) container's interface config
- there are some ways to setup an container's IP address
- a container can, most of the times, overide IP address assignment on lxc
config
- the best setup, IMHO, is to either:
--> have container using dhcp, and setup the DHCP server (which include
lxd's dnsmasq) to assign persistent ip address. This is the example listed
on https://stgraber.org/2016/10/27/network-management-with-lxd-2-3/ .  OR
--> configure the container OS (e.g. on /etc/network/interfaces, or
equivalent distro location) to use static IP


> Did not work:
>
> devices:
>   default:
>     ipv4.address: 192.168.0.36/24
>     name: eth0
>     nictype: bridged
>     parent: lxdbr0
>     type: nic
>
>
Which is the correct behavior. Since lxdbr0 is on separate network from
your host's eth0



> Did work:
>
> devices:
>   default:
>     ipv4.address: 192.168.0.36/24
>     name: eth0
>     nictype: bridged
>     parent: br0
>     type: nic
>
>
This is probably where you don't setup any IP configuration on the
container side, so it continue to use whatever address assigned by lxd when
the container started. For this type of setup though, I recommend to NOT
rely on lxc config file, but rather set it up directly in the container OS.

-- 
Fajar
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