Merge pull request #513 from nvgoldin/dns_backward

 Make DNS changes introduced in 6386bc8 backward compatible

lago/prefix.py

@@ -29,6 +29,7 @@
 import urllib
 import uuid
 import warnings
+import pkg_resources
 from os.path import join
 
 import xmltodict
@@ -107,7 +108,8 @@ def __init__(self, prefix):
         self._virt_env = None
         self._metadata = None
 
-    def _get_metadata(self):
+    @property
+    def metadata(self):
         """
         Retrieve the metadata info for this prefix
 
@@ -117,11 +119,7 @@ def _get_metadata(self):
         if self._metadata is None:
             try:
                 with open(self.paths.metadata()) as metadata_fd:
-                    json_data = metadata_fd.read()
-                    if json_data:
-                        self._metadata = json.load(json_data)
-                    else:
-                        raise IOError()
+                    self._metadata = json.load(metadata_fd)
             except IOError:
                 self._metadata = {}
         return self._metadata
@@ -134,7 +132,7 @@ def _save_metadata(self):
             None
         """
         with open(self.paths.metadata(), 'w') as metadata_fd:
-            utils.json_dump(self._get_metadata(), metadata_fd)
+            utils.json_dump(self.metadata, metadata_fd)
 
     def save(self):
         """
@@ -1203,6 +1201,10 @@ def virt_conf(
                 net_specs=conf['nets'],
             )
 
+            self._metadata = {
+                'lago_version': pkg_resources.get_distribution("lago").version,
+            }
+
             if do_bootstrap:
                 self.virt_env.bootstrap()
 

lago/providers/libvirt/network.py

@@ -34,14 +34,15 @@
 
 
 class Network(object):
-    def __init__(self, env, spec):
+    def __init__(self, env, spec, compat):
         self._env = env
         libvirt_url = config.get('libvirt_url')
         self.libvirt_con = libvirt_utils.get_libvirt_connection(
             name=env.uuid + libvirt_url,
             libvirt_url=libvirt_url,
         )
         self._spec = spec
+        self.compat = compat
 
     def name(self):
         return self._spec['name']
@@ -142,8 +143,8 @@ def _generate_dns_disable(self):
         dns = ET.Element('dns', enable='no')
         return dns
 
-    def _generate_main_dns(self, records, domain, subnet):
-        dns = ET.Element('dns', forwardPlainNames='no')
+    def _generate_main_dns(self, records, subnet, forward_plain='no'):
+        dns = ET.Element('dns', forwardPlainNames=forward_plain)
         reverse_records = defaultdict(list)
         ipv6_prefix = self._ipv6_prefix(subnet=subnet)
         for hostname, ip in records.iteritems():
@@ -227,24 +228,48 @@ def make_ipv4(last):
                     )
                 )
 
-        if self.is_management():
-            domain_xml = ET.Element(
-                'domain', name=self._spec['dns_domain_name'], localOnly='yes'
-            )
-            net_xml.append(domain_xml)
-            net_xml.append(
-                self._generate_main_dns(
-                    self._spec['dns_records'], self._spec['dns_domain_name'],
-                    subnet
+        if utils.ver_cmp(self.compat, '0.36.11') >= 0:
+            if self.is_management():
+                domain_xml = ET.Element(
+                    'domain',
+                    name=self._spec['dns_domain_name'],
+                    localOnly='yes'
                 )
-            )
+                net_xml.append(domain_xml)
+                net_xml.append(
+                    self._generate_main_dns(self._spec['dns_records'], subnet)
+                )
+            else:
+                if self.libvirt_con.getLibVersion() < 2002000:
+                    net_xml.append(
+                        self._generate_dns_forward(self._spec['dns_forward'])
+                    )
+                else:
+                    net_xml.append(self._generate_dns_disable())
         else:
-            if self.libvirt_con.getLibVersion() < 2002000:
+            LOGGER.debug(
+                'Generating network XML with compatibility prior to %s',
+                self.compat
+            )
+            # Prior to v0.37, DNS records were only the  mappings of the
+            # management network.
+            if self.is_management():
+                if 'dns_domain_name' in self._spec:
+                    domain_xml = ET.Element(
+                        'domain',
+                        name=self._spec['dns_domain_name'],
+                        localOnly='yes'
+                    )
+                    net_xml.append(domain_xml)
+
                 net_xml.append(
-                    self._generate_dns_forward(self._spec['dns_forward'])
+                    self._generate_main_dns(
+                        self._spec['mapping'], subnet, forward_plain='yes'
+                    )
                 )
             else:
-                net_xml.append(self._generate_dns_disable())
+                dns = ET.Element('dns', forwardPlainNames='yes', enable='yes')
+                net_xml.append(dns)
 
         LOGGER.debug(
             'Generated Network XML\n {0}'.

lago/utils.py

@@ -33,6 +33,7 @@
 import textwrap
 import time
 import yaml
+import pkg_resources
 from io import StringIO
 import lockfile
 import argparse
@@ -773,6 +774,24 @@ def remove_key(path, spec):
             raise
 
 
+def ver_cmp(ver1, ver2):
+    """
+    Compare lago versions
+
+    Args:
+        ver1(str): version string
+        ver2(str): version string
+
+    Returns:
+        Return negative if ver1<ver2, zero if ver1==ver2, positive if
+        ver1>ver2.
+    """
+
+    return cmp(
+        pkg_resources.parse_version(ver1), pkg_resources.parse_version(ver2)
+    )
+
+
 class LagoException(Exception):
     pass
 

lago/virt.py

@@ -101,7 +101,7 @@ def _create_net(self, net_spec):
             cls = NATNetwork
         elif net_spec['type'] == 'bridge':
             cls = BridgeNetwork
-        return cls(self, net_spec)
+        return cls(self, net_spec, compat=self.get_compat())
 
     def _create_vm(self, vm_spec):
         default_vm_type = config.get('default_vm_type')
@@ -511,3 +511,10 @@ def get_snapshots(self, domains=None):
             snapshots[vm_name] = vm._spec['snapshots']
 
         return snapshots
+
+    def get_compat(self):
+        """Get compatibility level for this environment - which is the Lago
+        version used to create this environment """
+        # Prior to version 0.37.0, the version which the environment was
+        # initialized in was not saved, so we default to 0.36.
+        return self.prefix.metadata.get('lago_version', '0.36.0')