Support attaching instances to a "physical" network that's using a bridge as parent

[mweinelt]

The host system provides a bridge interface that is connected to a physical interface.

When integrating that bridge via the physical nic type and passing the bridge interface as the parentI get the following error when starting the VM.

Failed to start device "eth-1": Failed to get PCI device info for "br-lan": open /sys/class/net/br-lan/device/uevent: no such file or directory

This is because the bridge does not have a device directory, but the code requires it for looking up PCIe information.

incus/internal/server/device/nic_physical.go

Line 211 in 36701b9

return nil, fmt.Errorf("Failed to get PCI device info for %q: %w", saveData["host_name"], err)

The documentation claims I can pass a bridge:

The physical network type connects to an existing physical network, which can be a network interface or a bridge, and serves as an uplink network for OVN.

https://linuxcontainers.org/incus/docs/main/reference/network_physical/

This issue is reproducible on incus 6.10.1.

[stgraber]

and serves as an uplink network for OVN

You're not trying to use it as an uplink for an OVN network but directly as a physical NIC on an instance, so that's probably why this is failing. I very commonly use a "physical" network with a bridge as parent for OVN uplinks and that works just fine.

[stgraber]

That said, I think it'd make sense to support attaching instances to such a "physical" type network, just using the normal bridge handling logic if we see it's a bridge.

I updated the issue title accordingly.

[snoby]

and serves as an uplink network for OVN

You're not trying to use it as an uplink for an OVN network but directly as a physical NIC on an instance, so that's probably why this is failing. I very commonly use a "physical" network with a bridge as parent for OVN uplinks and that works just fine.

I've been 'battling' with this very issue recently. Placing the ovn network behind a managed incus bridge essentially makes everything in the ovn network double NAT. Perhaps I don't fully understand the reasoning for why macvlan and physical networks can not be parents to the ovn bridge.
Why must I create a managed bridge with NAT enabled to be the parent of the ovn network?

[stgraber]

You don't. Most production deployments use a physical managed network as the uplink for OVN.

[stgraber]

That said, OVN cannot use macvlan for that, but it can use a physical network interface or a VLAN. The main restriction is that this interface or VLAN must be unconfigured on the host, so no IP config on it at all as when OVN will consume it, it will no longer be usable by the host system.

[stgraber]

Anyway, that's unrelated to this issue.

[snoby]

You don't. Most production deployments use a physical managed network as the uplink for OVN.

I understand, and i won't add any more to this issue as I do not want to hijack the thread, however even sr-iov interfaces can not be used.
Thanks for your answers and great project!

[oronila]

Hey I am a UT student, I would like to work on this issue. I am working with a partner who will also comment on this.

[stgraber]

Assigned it to you!

[NathanChase22]

Hey, its the partner here