Handle FAM monitor failures more gracefully:

* Where possible, create the file or directory that is about to be
  monitored.  This ensures that content can be added later without
  need to restart Bcfg2.  (Otherwise, adding the monitor would fail,
  and so when you did create the file in question, bcfg2-server would
  never be notified of it.)
* When not possible, give better error messages.

2 files changed, 52 insertions, 11 deletions

diff --git a/src/lib/Bcfg2/Server/Plugin/base.py b/src/lib/Bcfg2/Server/Plugin/base.py
index f7bc08717..ecd970b54 100644
--- a/src/lib/Bcfg2/Server/Plugin/base.py
+++ b/src/lib/Bcfg2/Server/Plugin/base.py
@@ -97,15 +97,21 @@ class Plugin(Debuggable):
         :param datastore: The path to the Bcfg2 repository on the
                           filesystem
         :type datastore: string
-        :raises: :class:`Bcfg2.Server.Plugin.exceptions.PluginInitError`
+        :raises: :exc:`OSError` if adding a file monitor failed;
+                 :class:`Bcfg2.Server.Plugin.exceptions.PluginInitError`
+                 on other errors
 
         .. autoattribute:: Bcfg2.Server.Plugin.base.Debuggable.__rmi__
         """
+        Debuggable.__init__(self, name=self.name)
         self.Entries = {}
         self.core = core
         self.data = os.path.join(datastore, self.name)
+        if not os.path.exists(self.data):
+            self.logger.warning("%s: %s does not exist, creating" %
+                                (self.name, self.data))
+            os.makedirs(self.data)
         self.running = True
-        Debuggable.__init__(self, name=self.name)
 
     @classmethod
     def init_repo(cls, repo):
@@ -125,5 +131,11 @@ class Plugin(Debuggable):
         self.debug_log("Shutting down %s plugin" % self.name)
         self.running = False
 
+    def set_debug(self, debug):
+        for entry in self.Entries.values():
+            if isinstance(entry, Debuggable):
+                entry.set_debug(debug)
+        return Debuggable.set_debug(self, debug)
+
     def __str__(self):
         return "%s Plugin" % self.__class__.__name__
diff --git a/src/lib/Bcfg2/Server/Plugin/helpers.py b/src/lib/Bcfg2/Server/Plugin/helpers.py
index 0b81077a3..448d8b3b6 100644
--- a/src/lib/Bcfg2/Server/Plugin/helpers.py
+++ b/src/lib/Bcfg2/Server/Plugin/helpers.py
@@ -193,7 +193,7 @@ class PluginDatabaseModel(object):
         app_label = "Server"
 
 
-class FileBacked(object):
+class FileBacked(Debuggable):
     """ This object caches file data in memory. FileBacked objects are
     principally meant to be used as a part of
     :class:`Bcfg2.Server.Plugin.helpers.DirectoryBacked`. """
@@ -206,7 +206,7 @@ class FileBacked(object):
                     changes
         :type fam: Bcfg2.Server.FileMonitor.FileMonitor
         """
-        object.__init__(self)
+        Debuggable.__init__(self)
 
         #: A string containing the raw data in this file
         self.data = ''
@@ -246,7 +246,7 @@ class FileBacked(object):
         return "%s: %s" % (self.__class__.__name__, self.name)
 
 
-class DirectoryBacked(object):
+class DirectoryBacked(Debuggable):
     """ DirectoryBacked objects represent a directory that contains
     files, represented by objects of the type listed in
     :attr:`__child__`, and other directories recursively.  It monitors
@@ -280,7 +280,7 @@ class DirectoryBacked(object):
         .. -----
         .. autoattribute:: __child__
         """
-        object.__init__(self)
+        Debuggable.__init__(self)
 
         self.data = os.path.normpath(data)
         self.fam = fam
@@ -299,8 +299,17 @@ class DirectoryBacked(object):
         self.handles = {}
 
         # Monitor everything in the plugin's directory
+        if not os.path.exists(self.data):
+            self.logger.warning("%s does not exist, creating" % self.data)
+            os.makedirs(self.data)
         self.add_directory_monitor('')
 
+    def set_debug(self, debug):
+        for entry in self.entries.values():
+            if isinstance(entry, Debuggable):
+                entry.set_debug(debug)
+        return Debuggable.set_debug(self, debug)
+
     def __getitem__(self, key):
         return self.entries[key]
 
@@ -459,7 +468,11 @@ class XMLFileBacked(FileBacked):
     #: behavior, set ``__identifier__`` to ``None``.
     __identifier__ = 'name'
 
-    def __init__(self, filename, fam=None, should_monitor=False):
+    #: If ``create`` is set, then it overrides the ``create`` argument
+    #: to the constructor.
+    create = None
+
+    def __init__(self, filename, fam=None, should_monitor=False, create=None):
         """
         :param filename: The full path to the file to cache and monitor
         :type filename: string
@@ -474,6 +487,13 @@ class XMLFileBacked(FileBacked):
                                :class:`Bcfg2.Server.Plugin.helpers.XMLDirectoryBacked`
                                object).
         :type should_monitor: bool
+        :param create: Create the file if it doesn't exist.
+                       ``create`` can be either an
+                       :class:`lxml.etree._Element` object, which will
+                       be used as initial content, or a string, which
+                       will be used as the name of the (empty) tag
+                       that will be the initial content of the file.
+        :type create: lxml.etree._Element or string
 
         .. -----
         .. autoattribute:: __identifier__
@@ -497,6 +517,17 @@ class XMLFileBacked(FileBacked):
         #: "Extra" files included in this file by XInclude.
         self.extras = []
 
+        if ((create or (self.create is not None and self.create))
+            and not os.path.exists(self.name)):
+            toptag = create or self.create
+            self.logger.warning("%s does not exist, creating" % self.name)
+            if hasattr(toptag, "getroottree"):
+                el = toptag
+            else:
+                el = lxml.etree.Element(toptag)
+            el.getroottree().write(self.name, xml_declaration=False,
+                                   pretty_print=True)
+
         #: Whether or not to monitor this file for changes.
         self.should_monitor = should_monitor
         if fam and should_monitor:
@@ -776,8 +807,8 @@ class XMLSrc(XMLFileBacked):
     __cacheobj__ = dict
     __priority_required__ = True
 
-    def __init__(self, filename, fam=None, should_monitor=False):
-        XMLFileBacked.__init__(self, filename, fam, should_monitor)
+    def __init__(self, filename, fam=None, should_monitor=False, create=None):
+        XMLFileBacked.__init__(self, filename, fam, should_monitor, create)
         self.items = {}
         self.cache = None
         self.pnode = None
@@ -1450,8 +1481,6 @@ class GroupSpool(Plugin, Generator):
     def __init__(self, core, datastore):
         Plugin.__init__(self, core, datastore)
         Generator.__init__(self)
-        if self.data[-1] == '/':
-            self.data = self.data[:-1]
 
         #: See :class:`Bcfg2.Server.Plugins.interfaces.Generator` for
         #: details on the Entries attribute.