add hierarchy plugin

src/lib/Bcfg2/Server/Plugins/Hierarchy.py

@@ -0,0 +1,95 @@
+"""
+  Support for metadata.Hierarchy, which adds
+  group hierarchy information with the profile
+  as anchor.
+"""
+
+import Bcfg2.Server.Plugin
+import Bcfg2.Server.Cache
+
+
+class Hierarchy(Bcfg2.Server.Plugin.Plugin,
+                Bcfg2.Server.Plugin.Connector):
+    """ adds the group hierarchy information to metadata
+    this information is lost in metadata.groups """
+
+    def __init__(self, core):
+        Bcfg2.Server.Plugin.Plugin.__init__(self, core)
+        Bcfg2.Server.Plugin.Connector.__init__(self)
+        self._cache = Bcfg2.Server.Cache.Cache("Hierarchy")
+
+        # inform us when a cache has been expired
+        # if a metadata object changed we have to
+        #  expire the cache as well
+        Bcfg2.Server.Cache.add_expire_hook(self._cache_expire_handler)
+
+    __init__.__doc__ = Bcfg2.Server.Plugin.Plugin.__init__.__doc__
+
+    def get_additional_data(self, metadata):
+        """ Parse through all groups of this client
+         add hierarchy information so it can be used
+         by other tools later """
+        self.debug_log("Hierarchy: Getting hierarchy for %s" %
+                       metadata.hostname)
+        if metadata.hostname in self._cache:
+            return self._cache[metadata.hostname]
+
+        # profile is our anchor group
+        # if we don't add it here we get a circular reference
+        visited_groups = set([metadata.profile])
+        hierarchy = dict()
+        for grp in metadata.groups:
+            hierarchy[grp] = set()
+            # get all children of the group
+            for child in self.core.metadata.groups_xml.xdata.xpath(
+                    "//Groups/Group[@name='%s']//Group" % grp):
+                # safeguard so only groups are added that this
+                # client is part of
+                if child.get('name') in metadata.groups:
+                    hierarchy[grp].add(child.get('name'))
+                    visited_groups.add(child.get('name'))
+
+        # postprocessing for groups that are added by probes or other plugins
+        # these are children of profile in the hierarchy
+        for grp in (set(metadata.groups) - visited_groups):
+            hierarchy[metadata.profile].add(grp)
+
+        self._cache[metadata.hostname] = hierarchy
+        return hierarchy
+
+    def _cache_expire_handler(self, tags, exact, count):
+        """ listens for caches that were expired.
+        If the metadata cache was expired for
+        a single host or entirely, then the local
+        cache is cleared as well. """
+        self.logger.debug("Hierarchy: Got Cache expire event. "
+                          "Tags: %s, exact=%s, count=%s" %
+                          (tags, exact, count))
+        if not tags or "Hierarchy" in tags:
+            return
+        try:
+            # tags are tuples (hostname, "Metadata") to expire
+            # a single hostname
+            # or ("Metadata",) if the whole metadata cache was cleared
+            if len(tags) == 2 and "Metadata" in tags:
+                if tags[0] == "Metadata":
+                    self._cache.expire()
+                    self.debug_log("Hierarchy: Expiring cache %s %s" %
+                                   (str(tags), str(exact)))
+                else:
+                    self._cache.expire(tags[0])
+                    self.debug_log("Hierarchy: Expiring cache %s %s" %
+                                   (str(tags), str(exact)))
+        except KeyError as error:
+            self.logger.warn("Hierarchy: Error choosing if"
+                             " cache should be expired. Expiring anyway. "
+                             "Tags %s, "
+                             "Error: %s"
+                             % (str(tags), error))
+            self._cache.expire()
+
+    def set_debug(self, debug):
+        rv = Bcfg2.Server.Plugin.Plugin.set_debug(self, debug)
+        return rv
+
+    set_debug.__doc__ = Bcfg2.Server.Plugin.Plugin.set_debug.__doc__