Add support for zones aliases

This commit adds support for zones aliases. This allows to define one or
multiple zone as aliases of an existing zone without using workarounds
like simlinks and miltiple "zones" entries in the configuration file.

An alias zone is share all of its content with it parent zone, only the
name of the zone is different.

```
zones:
  example.com.:
    aliases:
      - example.net.
      - example.org.
    sources:
      - in
    targets:
      - out
```

Known issues:
- No documentation,
- Only the `octodns-sync` and `octodns-validate` commands supports
aliases zones at this time,

I added a loop in the manager init function which convert all alias
zone to "real" ones during config validation, however I'm not sure
this is the right approach. Comments welcome.

octodns/manager.py

@@ -121,6 +121,20 @@ class Manager(object):
                 raise ManagerException('Incorrect provider config for {}'
                                        .format(provider_name))
 
+        for zone_name, zone_config in self.config['zones'].copy().items():
+            if 'aliases' in zone_config:
+                for alias in zone_config['aliases']:
+                    if alias in self.config['zones']:
+                        self.log.exception('Invalid zone alias')
+                        raise ManagerException('Invalid zone alias {}: '
+                                               'this zone already exists'
+                                               .format(alias))
+
+                    self.config['zones'][alias] = zone_config
+                    self.config['zones'][alias]['template_zone'] = zone_name
+
+                del self.config['zones'][zone_name]['aliases']
+
         zone_tree = {}
         # sort by reversed strings so that parent zones always come first
         for name in sorted(self.config['zones'].keys(), key=lambda s: s[::-1]):
@@ -222,12 +236,14 @@ class Manager(object):
         self.log.debug('configured_sub_zones: subs=%s', sub_zone_names)
         return set(sub_zone_names)
 
-    def _populate_and_plan(self, zone_name, sources, targets, lenient=False):
+    def _populate_and_plan(self, zone_name, template_zone, sources, targets,
+                           lenient=False):
 
-        self.log.debug('sync:   populating, zone=%s, lenient=%s',
-                       zone_name, lenient)
+        self.log.debug('sync:   populating, zone=%s, template=%s, lenient=%s',
+                       zone_name, template_zone, lenient)
         zone = Zone(zone_name,
-                    sub_zones=self.configured_sub_zones(zone_name))
+                    sub_zones=self.configured_sub_zones(zone_name),
+                    template_zone=template_zone)
         for source in sources:
             try:
                 source.populate(zone, lenient=lenient)
@@ -269,6 +285,7 @@ class Manager(object):
         for zone_name, config in zones:
             self.log.info('sync:   zone=%s', zone_name)
             lenient = config.get('lenient', False)
+            template_zone = config.get('template_zone', zone_name)
             try:
                 sources = config['sources']
             except KeyError:
@@ -318,8 +335,9 @@ class Manager(object):
                                        .format(zone_name, target))
 
             futures.append(self._executor.submit(self._populate_and_plan,
-                                                 zone_name, sources,
-                                                 targets, lenient=lenient))
+                                                 zone_name, template_zone,
+                                                 sources, targets,
+                                                 lenient=lenient))
 
         # Wait on all results and unpack/flatten them in to a list of target &
         # plan pairs.
@@ -413,7 +431,9 @@ class Manager(object):
 
     def validate_configs(self):
         for zone_name, config in self.config['zones'].items():
-            zone = Zone(zone_name, self.configured_sub_zones(zone_name))
+            template_zone = config.get('template_zone', zone_name)
+            zone = Zone(zone_name, self.configured_sub_zones(zone_name),
+                        template_zone)
 
             try:
                 sources = config['sources']

octodns/provider/yaml.py

@@ -139,8 +139,8 @@ class YamlProvider(BaseProvider):
                            filename)
 
     def populate(self, zone, target=False, lenient=False):
-        self.log.debug('populate: name=%s, target=%s, lenient=%s', zone.name,
-                       target, lenient)
+        self.log.debug('populate: name=%s, template=%s, target=%s, lenient=%s',
+                       zone.name, zone.template_zone, target, lenient)
 
         if target:
             # When acting as a target we ignore any existing records so that we
@@ -148,7 +148,9 @@ class YamlProvider(BaseProvider):
             return False
 
         before = len(zone.records)
-        filename = join(self.directory, '{}yaml'.format(zone.name))
+        filename = join(self.directory, '{}yaml'.format(zone.template_zone
+                                                        if zone.template_zone
+                                                        else zone.name))
         self._populate_from_file(filename, zone, lenient)
 
         self.log.info('populate:   found %s records, exists=False',
@@ -243,11 +245,12 @@ class SplitYamlProvider(YamlProvider):
         super(SplitYamlProvider, self).__init__(id, directory, *args, **kwargs)
 
     def _zone_directory(self, zone):
-        return join(self.directory, zone.name)
+        return join(self.directory, zone.template_zone if zone.template_zone
+                    else zone.name)
 
     def populate(self, zone, target=False, lenient=False):
-        self.log.debug('populate: name=%s, target=%s, lenient=%s', zone.name,
-                       target, lenient)
+        self.log.debug('populate: name=%s, template=%s, target=%s, lenient=%s',
+                       zone.name, zone.template_zone, target, lenient)
 
         if target:
             # When acting as a target we ignore any existing records so that we

octodns/zone.py

@@ -35,13 +35,14 @@ def _is_eligible(record):
 class Zone(object):
     log = getLogger('Zone')
 
-    def __init__(self, name, sub_zones):
+    def __init__(self, name, sub_zones, template_zone=None):
         if not name[-1] == '.':
             raise Exception('Invalid zone name {}, missing ending dot'
                             .format(name))
         # Force everything to lowercase just to be safe
         self.name = text_type(name).lower() if name else name
         self.sub_zones = sub_zones
+        self.template_zone = template_zone
         # We're grouping by node, it allows us to efficiently search for
         # duplicates and detect when CNAMEs co-exist with other records
         self._records = defaultdict(set)

tests/config/bad-zone-aliases.yaml

@@ -0,0 +1,17 @@
+manager:
+  max_workers: 2
+providers:
+  in:
+    class: octodns.provider.yaml.YamlProvider
+    directory: tests/config
+  dump:
+    class: octodns.provider.yaml.YamlProvider
+    directory: env/YAML_TMP_DIR
+zones:
+  unit.tests.:
+    aliases:
+      - unit.tests.
+    sources:
+      - in
+    targets:
+      - dump

tests/config/simple-aliases.yaml

@@ -0,0 +1,17 @@
+manager:
+  max_workers: 2
+providers:
+  in:
+    class: octodns.provider.yaml.YamlProvider
+    directory: tests/config
+  dump:
+    class: octodns.provider.yaml.YamlProvider
+    directory: env/YAML_TMP_DIR
+zones:
+  unit.tests.:
+    aliases:
+      - unit-alias.tests.
+    sources:
+      - in
+    targets:
+      - dump

tests/test_octodns_manager.py

@@ -290,7 +290,8 @@ class TestManager(TestCase):
                     pass
 
             # This should be ok, we'll fall back to not passing it
-            manager._populate_and_plan('unit.tests.', [NoLenient()], [])
+            manager._populate_and_plan('unit.tests.', 'unit.tests.',
+                                       [NoLenient()], [])
 
             class NoZone(SimpleProvider):
 
@@ -299,7 +300,16 @@ class TestManager(TestCase):
 
             # This will blow up, we don't fallback for source
             with self.assertRaises(TypeError):
-                manager._populate_and_plan('unit.tests.', [NoZone()], [])
+                manager._populate_and_plan('unit.tests.', 'unit.tests.',
+                                           [NoZone()], [])
+
+    def test_zone_aliases(self):
+        Manager(get_config_filename('simple-aliases.yaml')).validate_configs()
+
+        with self.assertRaises(ManagerException) as ctx:
+            Manager(get_config_filename('bad-zone-aliases.yaml')) \
+                .validate_configs()
+        self.assertTrue('Invalid zone alias' in text_type(ctx.exception))
 
 
 class TestMainThreadExecutor(TestCase):