Merging trunk

2 files changed, 199 insertions, 9 deletions

diff --git a/plugins/xenserver/xenapi/etc/xapi.d/plugins/pluginlib_nova.py b/plugins/xenserver/xenapi/etc/xapi.d/plugins/pluginlib_nova.py
index 2d323a016..8e7a829d5 100755
--- a/plugins/xenserver/xenapi/etc/xapi.d/plugins/pluginlib_nova.py
+++ b/plugins/xenserver/xenapi/etc/xapi.d/plugins/pluginlib_nova.py
@@ -45,6 +45,7 @@ class PluginError(Exception):
     def __init__(self, *args):
         Exception.__init__(self, *args)
 
+
 class ArgumentError(PluginError):
     """Raised when required arguments are missing, argument values are invalid,
     or incompatible arguments are given.
@@ -67,6 +68,7 @@ def ignore_failure(func, *args, **kwargs):
 
 ARGUMENT_PATTERN = re.compile(r'^[a-zA-Z0-9_:\.\-,]+$')
 
+
 def validate_exists(args, key, default=None):
     """Validates that a string argument to a RPC method call is given, and
     matches the shell-safe regex, with an optional default value in case it
@@ -76,20 +78,24 @@ def validate_exists(args, key, default=None):
     """
     if key in args:
         if len(args[key]) == 0:
-            raise ArgumentError('Argument %r value %r is too short.' % (key, args[key]))
+            raise ArgumentError('Argument %r value %r is too short.' %
+                    (key, args[key]))
         if not ARGUMENT_PATTERN.match(args[key]):
-            raise ArgumentError('Argument %r value %r contains invalid characters.' % (key, args[key]))
+            raise ArgumentError('Argument %r value %r contains invalid '
+                    'characters.' % (key, args[key]))
         if args[key][0] == '-':
-            raise ArgumentError('Argument %r value %r starts with a hyphen.' % (key, args[key]))
+            raise ArgumentError('Argument %r value %r starts with a hyphen.'
+                    % (key, args[key]))
         return args[key]
     elif default is not None:
         return default
     else:
         raise ArgumentError('Argument %s is required.' % key)
 
+
 def validate_bool(args, key, default=None):
-    """Validates that a string argument to a RPC method call is a boolean string,
-    with an optional default value in case it does not exist.
+    """Validates that a string argument to a RPC method call is a boolean
+    string, with an optional default value in case it does not exist.
 
     Returns the python boolean value.
     """
@@ -99,7 +105,9 @@ def validate_bool(args, key, default=None):
     elif value.lower() == 'false':
         return False
     else:
-        raise ArgumentError("Argument %s may not take value %r. Valid values are ['true', 'false']." % (key, value))
+        raise ArgumentError("Argument %s may not take value %r. "
+                "Valid values are ['true', 'false']." % (key, value))
+
 
 def exists(args, key):
     """Validates that a freeform string argument to a RPC method call is given.
@@ -110,6 +118,7 @@ def exists(args, key):
     else:
         raise ArgumentError('Argument %s is required.' % key)
 
+
 def optional(args, key):
     """If the given key is in args, return the corresponding value, otherwise
     return None"""
@@ -122,13 +131,14 @@ def get_this_host(session):
 
 def get_domain_0(session):
     this_host_ref = get_this_host(session)
-    expr = 'field "is_control_domain" = "true" and field "resident_on" = "%s"' % this_host_ref
+    expr = 'field "is_control_domain" = "true" and field "resident_on" = "%s"'
+    expr = expr % this_host_ref
     return session.xenapi.VM.get_all_records_where(expr).keys()[0]
 
 
 def create_vdi(session, sr_ref, name_label, virtual_size, read_only):
     vdi_ref = session.xenapi.VDI.create(
-        { 'name_label': name_label,
+         {'name_label': name_label,
           'name_description': '',
           'SR': sr_ref,
           'virtual_size': str(virtual_size),
@@ -138,7 +148,7 @@ def create_vdi(session, sr_ref, name_label, virtual_size, read_only):
           'xenstore_data': {},
           'other_config': {},
           'sm_config': {},
-          'tags': [] })
+          'tags': []})
     logging.debug('Created VDI %s (%s, %s, %s) on %s.', vdi_ref, name_label,
                   virtual_size, read_only, sr_ref)
     return vdi_ref
diff --git a/plugins/xenserver/xenapi/etc/xapi.d/plugins/xenstore.py b/plugins/xenserver/xenapi/etc/xapi.d/plugins/xenstore.py
new file mode 100755
index 000000000..695bf3448
--- /dev/null
+++ b/plugins/xenserver/xenapi/etc/xapi.d/plugins/xenstore.py
@@ -0,0 +1,180 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2010 Citrix Systems, Inc.
+# Copyright 2010 OpenStack LLC.
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+#
+# XenAPI plugin for reading/writing information to xenstore
+#
+
+try:
+    import json
+except ImportError:
+    import simplejson as json
+import subprocess
+
+import XenAPIPlugin
+
+import pluginlib_nova as pluginlib
+pluginlib.configure_logging("xenstore")
+
+
+def jsonify(fnc):
+    def wrapper(*args, **kwargs):
+        return json.dumps(fnc(*args, **kwargs))
+    return wrapper
+
+
+@jsonify
+def read_record(self, arg_dict):
+    """Returns the value stored at the given path for the given dom_id.
+    These must be encoded as key/value pairs in arg_dict. You can
+    optinally include a key 'ignore_missing_path'; if this is present
+    and boolean True, attempting to read a non-existent path will return
+    the string 'None' instead of raising an exception.
+    """
+    cmd = "xenstore-read /local/domain/%(dom_id)s/%(path)s" % arg_dict
+    try:
+        return _run_command(cmd).rstrip("\n")
+    except pluginlib.PluginError, e:
+        if arg_dict.get("ignore_missing_path", False):
+            cmd = "xenstore-exists /local/domain/%(dom_id)s/%(path)s; echo $?"
+            cmd = cmd % arg_dict
+            ret = _run_command(cmd).strip()
+            # If the path exists, the cmd should return "0"
+            if ret != "0":
+                # No such path, so ignore the error and return the
+                # string 'None', since None can't be marshalled
+                # over RPC.
+                return "None"
+        # Either we shouldn't ignore path errors, or another
+        # error was hit. Re-raise.
+        raise
+
+
+@jsonify
+def write_record(self, arg_dict):
+    """Writes to xenstore at the specified path. If there is information
+    already stored in that location, it is overwritten. As in read_record,
+    the dom_id and path must be specified in the arg_dict; additionally,
+    you must specify a 'value' key, whose value must be a string. Typically,
+    you can json-ify more complex values and store the json output.
+    """
+    cmd = "xenstore-write /local/domain/%(dom_id)s/%(path)s '%(value)s'"
+    cmd = cmd % arg_dict
+    _run_command(cmd)
+    return arg_dict["value"]
+
+
+@jsonify
+def list_records(self, arg_dict):
+    """Returns all the stored data at or below the given path for the
+    given dom_id. The data is returned as a json-ified dict, with the
+    path as the key and the stored value as the value. If the path
+    doesn't exist, an empty dict is returned.
+    """
+    cmd = "xenstore-ls /local/domain/%(dom_id)s/%(path)s" % arg_dict
+    cmd = cmd.rstrip("/")
+    try:
+        recs = _run_command(cmd)
+    except pluginlib.PluginError, e:
+        if "No such file or directory" in "%s" % e:
+            # Path doesn't exist.
+            return {}
+        return str(e)
+        raise
+    base_path = arg_dict["path"]
+    paths = _paths_from_ls(recs)
+    ret = {}
+    for path in paths:
+        if base_path:
+            arg_dict["path"] = "%s/%s" % (base_path, path)
+        else:
+            arg_dict["path"] = path
+        rec = read_record(self, arg_dict)
+        try:
+            val = json.loads(rec)
+        except ValueError:
+            val = rec
+        ret[path] = val
+    return ret
+
+
+@jsonify
+def delete_record(self, arg_dict):
+    """Just like it sounds: it removes the record for the specified
+    VM and the specified path from xenstore.
+    """
+    cmd = "xenstore-rm /local/domain/%(dom_id)s/%(path)s" % arg_dict
+    return _run_command(cmd)
+
+
+def _paths_from_ls(recs):
+    """The xenstore-ls command returns a listing that isn't terribly
+    useful. This method cleans that up into a dict with each path
+    as the key, and the associated string as the value.
+    """
+    ret = {}
+    last_nm = ""
+    level = 0
+    path = []
+    ret = []
+    for ln in recs.splitlines():
+        nm, val = ln.rstrip().split(" = ")
+        barename = nm.lstrip()
+        this_level = len(nm) - len(barename)
+        if this_level == 0:
+            ret.append(barename)
+            level = 0
+            path = []
+        elif this_level == level:
+            # child of same parent
+            ret.append("%s/%s" % ("/".join(path), barename))
+        elif this_level > level:
+            path.append(last_nm)
+            ret.append("%s/%s" % ("/".join(path), barename))
+            level = this_level
+        elif this_level < level:
+            path = path[:this_level]
+            ret.append("%s/%s" % ("/".join(path), barename))
+            level = this_level
+        last_nm = barename
+    return ret
+
+
+def _run_command(cmd):
+    """Abstracts out the basics of issuing system commands. If the command
+    returns anything in stderr, a PluginError is raised with that information.
+    Otherwise, the output from stdout is returned.
+    """
+    pipe = subprocess.PIPE
+    proc = subprocess.Popen([cmd], shell=True, stdin=pipe, stdout=pipe,
+            stderr=pipe, close_fds=True)
+    proc.wait()
+    err = proc.stderr.read()
+    if err:
+        raise pluginlib.PluginError(err)
+    return proc.stdout.read()
+
+
+if __name__ == "__main__":
+    XenAPIPlugin.dispatch(
+        {"read_record": read_record,
+        "write_record": write_record,
+        "list_records": list_records,
+        "delete_record": delete_record})