On 6/12/26 07:14, Radosław Śmigielski via Devel wrote:
> From: Radoslaw Smigielski <[email protected]>
>
> LXC domains did not assign device aliases to network interface devices
> during domain startup.
>
> This change assigns aliases in the format 'net0', 'net1', etc. to all
> network interfaces during domain startup, following the same pattern
> used for console and filesystem devices.
>
> Before this patch, virsh dumpxml showed network interfaces without aliases:
>
> <interface type='network'>
> <mac address='52:54:00:12:34:56'/>
> <source network='default'/>
> </interface>
>
> After this patch, network interfaces have auto-generated aliases:
>
> <interface type='network'>
> <mac address='52:54:00:12:34:56'/>
> <source network='default'/>
> <alias name='net0'/>
> </interface>
>
> This ensures all LXC device types (consoles, filesystems, and network
> interfaces) have consistent alias assigned.
>
> Signed-off-by: Radoslaw Smigielski <[email protected]>
> ---
> src/lxc/lxc_process.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/src/lxc/lxc_process.c b/src/lxc/lxc_process.c
> index aae9fcc9dfd1..f93f3f05c394 100644
> --- a/src/lxc/lxc_process.c
> +++ b/src/lxc/lxc_process.c
> @@ -1356,6 +1356,12 @@ int virLXCProcessStart(virLXCDriver * driver,
> vm->def->fss[i]->info.alias = g_strdup_printf("fs%zu", i);
> }
>
> + VIR_DEBUG("Setting up network interface aliases");
> + for (i = 0; i < vm->def->nnets; i++) {
> + g_free(vm->def->nets[i]->info.alias);
Again, no need to free this.
> + vm->def->nets[i]->info.alias = g_strdup_printf("net%zu", i);
> + }
> +
> VIR_DEBUG("Setting up Interfaces");
> if (virLXCProcessSetupInterfaces(driver, vm->def, &veths) < 0)
> goto cleanup;
This covers domain startup, but there's one more case to cover: device
hotplug.
For LXC domains it is possible to attach an <interface/> on the fly, see
lxcDomainAttachDeviceLive(). Now, attaching and detaching interfaces
complicates alias generation a bit, because we're not starting with an
empty canvas. For instance, I can start a domain with one interface and
it'd get "net0" alias. Then hotplug another one (say, it'd get "net1"
alias) and detach "net0" subsequently. At this point we have
vm->def->nnets = 1, and hotplugging another interface must NOT assign
"net1" alias because it is already used.
But we can re-use what other drivers have, say QEMU driver. If you take
a look at how aliases are assigned there, you'd find
qemuAssignDeviceNetAlias() which iterates over array of existing
interfaces and finds next unused index. We can use the same approach in
LXC and then just call the function from lxcDomainAttachDeviceNetLive()
- the line just after call to virDomainActualNetDefValidate() looks like
a good fit.
Michal
