[lxc-devel] [lxd/master] Network: Generates EUI64 IPv6 DNS record for OVN NICs when static IPv4 address is defined

[tomponline on Github]

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From c470380fd10673ee00dd9bf1e28371bf4e3fb2bb Mon Sep 17 00:00:00 2001
From: Thomas Parrott <thomas.parrott at canonical.com>
Date: Fri, 16 Oct 2020 10:18:27 +0100
Subject: [PATCH 1/2] lxd/device/nic/ovn: Improved error messages

Signed-off-by: Thomas Parrott <thomas.parrott at canonical.com>
---
 lxd/device/nic_ovn.go | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lxd/device/nic_ovn.go b/lxd/device/nic_ovn.go
index 766adbcdf0..091888ab60 100644
--- a/lxd/device/nic_ovn.go
+++ b/lxd/device/nic_ovn.go
@@ -300,7 +300,7 @@ func (d *nicOVN) Start() (*deviceConfig.RunConfig, error) {
 
 		internalRoutes, err = network.SubnetParseAppend(internalRoutes, strings.Split(d.config[key], ",")...)
 		if err != nil {
-			return nil, errors.Wrapf(err, "Invalid %s", key)
+			return nil, errors.Wrapf(err, "Invalid %q value", key)
 		}
 	}
 
@@ -312,7 +312,7 @@ func (d *nicOVN) Start() (*deviceConfig.RunConfig, error) {
 
 		externalRoutes, err = network.SubnetParseAppend(externalRoutes, strings.Split(d.config[key], ",")...)
 		if err != nil {
-			return nil, errors.Wrapf(err, "Invalid %s", key)
+			return nil, errors.Wrapf(err, "Invalid %q value", key)
 		}
 	}
 
@@ -439,7 +439,7 @@ func (d *nicOVN) Stop() (*deviceConfig.RunConfig, error) {
 
 		internalRoutes, err = network.SubnetParseAppend(internalRoutes, strings.Split(d.config[key], ",")...)
 		if err != nil {
-			return nil, errors.Wrapf(err, "Invalid %s", key)
+			return nil, errors.Wrapf(err, "Invalid %q value", key)
 		}
 	}
 
@@ -451,7 +451,7 @@ func (d *nicOVN) Stop() (*deviceConfig.RunConfig, error) {
 
 		externalRoutes, err = network.SubnetParseAppend(externalRoutes, strings.Split(d.config[key], ",")...)
 		if err != nil {
-			return nil, errors.Wrapf(err, "Invalid %s", key)
+			return nil, errors.Wrapf(err, "Invalid %q value", key)
 		}
 	}
 

From 1666e7465339f83f126960324849268e495a4c71 Mon Sep 17 00:00:00 2001
From: Thomas Parrott <thomas.parrott at canonical.com>
Date: Fri, 16 Oct 2020 14:32:48 +0100
Subject: [PATCH 2/2] lxd/network/driver/ovn: Generates static EUI64 IPv6
 address for instance switch ports in instanceDevicePortAdd

When only static IPv4 addresses have been added to a logical switch port.

This ensures that the switch port has an IPv6 address, as OVN has a limitation that prevents a port from being statically addressed for IPv4 and dynamically allocated for IPv6.

This in turn meant that if using the `ipv4.address` key without an associated `ipv6.address` key, then AAAA DNS record would not be created.

Signed-off-by: Thomas Parrott <thomas.parrott at canonical.com>
---
 lxd/network/driver_ovn.go | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/lxd/network/driver_ovn.go b/lxd/network/driver_ovn.go
index a6dc816a7a..47f1c0daf9 100644
--- a/lxd/network/driver_ovn.go
+++ b/lxd/network/driver_ovn.go
@@ -1873,6 +1873,30 @@ func (n *ovn) instanceDevicePortAdd(instanceID int, instanceName string, deviceN
 		if err != nil {
 			return "", err
 		}
+
+		// If port isn't going to have fully dynamic IPs allocated by OVN, and instead only static IPv4
+		// addresses have been added, then add an EUI64 static IPv6 address so that the switch port has an
+		// IPv6 address that will be used to generate a DNS record. This works around a limitation in OVN
+		// that prevents us requesting dynamic IPv6 address allocation when static IPv4 allocation is used.
+		if len(ips) > 0 {
+			hasIPv6 := false
+			for _, ip := range ips {
+				if ip.To4() == nil {
+					hasIPv6 = true
+					break
+				}
+			}
+
+			if !hasIPv6 {
+				eui64IP, err := eui64.ParseMAC(routerIntPortIPv6Net.IP, mac)
+				if err != nil {
+					return "", errors.Wrapf(err, "Failed generating EUI64 for instance port %q", mac.String())
+				}
+
+				// Add EUI64 to list of static IPs for instance port.
+				ips = append(ips, eui64IP)
+			}
+		}
 	}
 
 	instancePortName := n.getInstanceDevicePortName(instanceID, deviceName)