net: IPv6, accept_ra, slaac, stateless (#51)

Router advertisements are required for the default route
to be set up, thus accept_ra should be enabled for
dhcpv6-stateful.

sysconf: IPV6_FORCE_ACCEPT_RA controls accept_ra sysctl.
eni: mode static and mode dhcp 'accept_ra' controls sysctl.

Add 'accept-ra: true|false' parameter to config v1 and
v2. When True: accept_ra is set to '1'. When False:
accept_ra is set to '0'. When not defined in config the
value is left to the operating system default.

This change also extend the IPv6 support to distinguish
between slaac and dhcpv6-stateless. SLAAC is autoconfig
without any options from DHCP, while stateless auto-configures
the address and the uses DHCP for other options.

LP: #1806014
LP: #1808647

1 files changed, 31 insertions, 3 deletions

diff --git a/cloudinit/net/sysconfig.py b/cloudinit/net/sysconfig.py
index fe0c67ca..310cdf01 100644
--- a/cloudinit/net/sysconfig.py
+++ b/cloudinit/net/sysconfig.py
@@ -14,7 +14,7 @@ from configobj import ConfigObj
 
 from . import renderer
 from .network_state import (
-    is_ipv6_addr, net_prefix_to_ipv4_mask, subnet_is_ipv6)
+    is_ipv6_addr, net_prefix_to_ipv4_mask, subnet_is_ipv6, IPV6_DYNAMIC_TYPES)
 
 LOG = logging.getLogger(__name__)
 NM_CFG_FILE = "/etc/NetworkManager/NetworkManager.conf"
@@ -335,6 +335,9 @@ class Renderer(renderer.Renderer):
                     continue
                 iface_cfg[new_key] = old_value
 
+        if iface['accept-ra'] is not None:
+            iface_cfg['IPV6_FORCE_ACCEPT_RA'] = iface['accept-ra']
+
     @classmethod
     def _render_subnets(cls, iface_cfg, subnets, has_default_route):
         # setting base values
@@ -351,6 +354,15 @@ class Renderer(renderer.Renderer):
                 iface_cfg['DHCPV6C'] = True
             elif subnet_type == 'ipv6_dhcpv6-stateless':
                 iface_cfg['IPV6INIT'] = True
+                # Configure network settings using SLAAC from RAs and optional
+                # info from dhcp server using DHCPv6
+                iface_cfg['IPV6_AUTOCONF'] = True
+                iface_cfg['DHCPV6C'] = True
+                # Use Information-request to get only stateless configuration
+                # parameters (i.e., without address).
+                iface_cfg['DHCPV6C_OPTIONS'] = '-S'
+            elif subnet_type == 'ipv6_slaac':
+                iface_cfg['IPV6INIT'] = True
                 # Configure network settings using SLAAC from RAs
                 iface_cfg['IPV6_AUTOCONF'] = True
             elif subnet_type in ['dhcp4', 'dhcp']:
@@ -398,10 +410,15 @@ class Renderer(renderer.Renderer):
             # metric may apply to both dhcp and static config
             if 'metric' in subnet:
                 iface_cfg['METRIC'] = subnet['metric']
+            # TODO(hjensas): Including dhcp6 here is likely incorrect. DHCPv6
+            # does not ever provide a default gateway, the default gateway
+            # come from RA's. (https://github.com/openSUSE/wicked/issues/570)
             if subnet_type in ['dhcp', 'dhcp4', 'dhcp6']:
                 if has_default_route and iface_cfg['BOOTPROTO'] != 'none':
                     iface_cfg['DHCLIENT_SET_DEFAULT_ROUTE'] = False
                 continue
+            elif subnet_type in IPV6_DYNAMIC_TYPES:
+                continue
             elif subnet_type == 'static':
                 if subnet_is_ipv6(subnet):
                     ipv6_index = ipv6_index + 1
@@ -444,10 +461,14 @@ class Renderer(renderer.Renderer):
     @classmethod
     def _render_subnet_routes(cls, iface_cfg, route_cfg, subnets):
         for _, subnet in enumerate(subnets, start=len(iface_cfg.children)):
+            subnet_type = subnet.get('type')
             for route in subnet.get('routes', []):
                 is_ipv6 = subnet.get('ipv6') or is_ipv6_addr(route['gateway'])
 
-                if _is_default_route(route):
+                # Any dynamic configuration method, slaac, dhcpv6-stateful/
+                # stateless should get router information from router RA's.
+                if (_is_default_route(route) and subnet_type not in
+                        IPV6_DYNAMIC_TYPES):
                     if (
                             (subnet.get('ipv4') and
                              route_cfg.has_set_default_ipv4) or
@@ -466,10 +487,17 @@ class Renderer(renderer.Renderer):
                     # TODO(harlowja): add validation that no other iface has
                     # also provided the default route?
                     iface_cfg['DEFROUTE'] = True
+                    # TODO(hjensas): Including dhcp6 here is likely incorrect.
+                    # DHCPv6 does not ever provide a default gateway, the
+                    # default gateway come from RA's.
+                    # (https://github.com/openSUSE/wicked/issues/570)
                     if iface_cfg['BOOTPROTO'] in ('dhcp', 'dhcp4', 'dhcp6'):
+                        # NOTE(hjensas): DHCLIENT_SET_DEFAULT_ROUTE is SuSE
+                        # only. RHEL, CentOS, Fedora does not implement this
+                        # option.
                         iface_cfg['DHCLIENT_SET_DEFAULT_ROUTE'] = True
                     if 'gateway' in route:
-                        if is_ipv6 or is_ipv6_addr(route['gateway']):
+                        if is_ipv6:
                             iface_cfg['IPV6_DEFAULTGW'] = route['gateway']
                             route_cfg.has_set_default_ipv6 = True
                         else: