Merge pull request #14424 from tlm/lxd-ipv6-support-2.9

#14424

Until now Juju has required ipv6 support to be disbaled on the network bridge created by lxd. We can now safely operate with ipv6 in Juju.

## Checklist

- ~[ ] Code style: imports ordered, good names, simple structure, etc~
- ~[ ] Comments saying why design decisions were made~
- [x] Go unit tests, with comments saying what you're testing
- ~[ ] [Integration tests](https://github.com/juju/juju/tree/develop/tests), with comments saying what you're testing~
- ~[ ] [doc.go](https://discourse.charmhub.io/t/readme-in-packages/451) added or updated in changed packages~

## QA steps

Install a fresh lxd daemon with ipv6 enabled on the default bridge and bootstrap juju. Confirm that no errors happen during bootstrap.

Deploy a workload and confirm that the agent.conf file gets the v6 address of the controller correctly.

## Documentation changes

N/A

## Bug reference

N/A

container/lxd/network.go

@@ -155,10 +155,6 @@ func (s *Server) ensureDefaultNetworking(profile *api.Profile, eTag string) erro
 		if err != nil {
 			return errors.Trace(err)
 		}
-	} else {
-		if err := verifyNoIPv6(net); err != nil {
-			return errors.Trace(err)
-		}
 	}
 
 	s.localBridgeName = network.DefaultLXDBridge
@@ -190,7 +186,6 @@ func (s *Server) ensureDefaultNetworking(profile *api.Profile, eTag string) erro
 // devices is suitable for LXD to work with Juju.
 func (s *Server) verifyNICsWithAPI(nics map[string]device) error {
 	checked := make([]string, 0, len(nics))
-	var ipV6ErrMsg error
 	for name, nic := range nics {
 		checked = append(checked, name)
 
@@ -210,11 +205,6 @@ func (s *Server) verifyNICsWithAPI(nics map[string]device) error {
 			return errors.Annotatef(err, "retrieving network %q", netName)
 		}
 
-		if err := verifyNoIPv6(net); err != nil {
-			ipV6ErrMsg = err
-			continue
-		}
-
 		// Versions of the LXD profile prior to 3.22 have a "nictype" member
 		// under NIC entries in the "devices" list.
 		// Later versions were observed to have this member absent,
@@ -228,17 +218,11 @@ func (s *Server) verifyNICsWithAPI(nics map[string]device) error {
 		return nil
 	}
 
-	// A nic with valid type found, but the network configures IPv6.
-	if ipV6ErrMsg != nil {
-		return ipV6ErrMsg
-	}
-
 	// No nics with a nictype of nicTypeBridged, nicTypeMACVLAN was found.
 	return errors.Errorf(fmt.Sprintf(
 		"no network device found with nictype %q or %q"+
 			"\n\tthe following devices were checked: %s"+
-			"\nNote: juju does not support IPv6."+
-			"\nReconfigure lxd to use a network of type %q or %q, disabling IPv6.",
+			"\nReconfigure lxd to use a network of type %q or %q.",
 		nicTypeBridged, nicTypeMACVLAN, strings.Join(checked, ", "), nicTypeBridged, nicTypeMACVLAN))
 }
 
@@ -305,27 +289,6 @@ func getProfileNICs(profile *api.Profile) map[string]device {
 	return nics
 }
 
-// verifyNoIPv6 checks that the input network has no IPv6 configuration.
-// An error is returned when it does.
-// TODO (manadart 2018-05-28) The intention is to support IPv6, so this
-// restriction is temporary.
-func verifyNoIPv6(net *api.Network) error {
-	if !net.Managed {
-		return nil
-	}
-	cfg, ok := net.Config["ipv6.address"]
-	if !ok {
-		return nil
-	}
-	if cfg == "none" {
-		return nil
-	}
-
-	return errors.Errorf("juju does not support IPv6. Disable IPv6 in LXD via:\n"+
-		"\tlxc network set %s ipv6.address none\n"+
-		"and run the command again", net.Name)
-}
-
 func isValidNICType(nic device) bool {
 	return nic["nictype"] == nicTypeBridged || nic["nictype"] == nicTypeMACVLAN
 }

container/lxd/network_test.go

@@ -216,11 +216,12 @@ func (s *networkSuite) TestVerifyNetworkDevicePresentBadNicType(c *gc.C) {
 	c.Assert(err, gc.ErrorMatches,
 		`profile "default": no network device found with nictype "bridged" or "macvlan"\n`+
 			`\tthe following devices were checked: eth0\n`+
-			`Note: juju does not support IPv6.\n`+
-			`Reconfigure lxd to use a network of type "bridged" or "macvlan", disabling IPv6.`)
+			`Reconfigure lxd to use a network of type "bridged" or "macvlan".`)
 }
 
-func (s *networkSuite) TestVerifyNetworkDeviceIPv6Present(c *gc.C) {
+// Juju used to fail when IPv6 was enabled on the lxd network. This test now
+// checks regression to make sure that we know longer fail.
+func (s *networkSuite) TestVerifyNetworkDeviceIPv6PresentNoFail(c *gc.C) {
 	ctrl := gomock.NewController(c)
 	defer ctrl.Finish()
 	cSvr := s.NewMockServerWithExtensions(ctrl, "network")
@@ -230,7 +231,7 @@ func (s *networkSuite) TestVerifyNetworkDeviceIPv6Present(c *gc.C) {
 		Managed: true,
 		NetworkPut: lxdapi.NetworkPut{
 			Config: map[string]string{
-				"ipv6.address": "something-not-nothing",
+				"ipv6.address": "2001:DB8::1",
 			},
 		},
 	}
@@ -240,10 +241,7 @@ func (s *networkSuite) TestVerifyNetworkDeviceIPv6Present(c *gc.C) {
 	c.Assert(err, jc.ErrorIsNil)
 
 	err = jujuSvr.VerifyNetworkDevice(defaultLegacyProfileWithNIC(), "")
-	c.Assert(err, gc.ErrorMatches,
-		`profile "default": juju does not support IPv6. Disable IPv6 in LXD via:\n`+
-			`\tlxc network set lxdbr0 ipv6.address none\n`+
-			`and run the command again`)
+	c.Assert(err, jc.ErrorIsNil)
 }
 
 func (s *networkSuite) TestVerifyNetworkDeviceNotPresentCreated(c *gc.C) {