Handle the case where newer versions of boto

are used that lazily load the metadata from the
ec2 metadata service.

1. Add a ec2_utils module that checks which version
   of boto is being used and under the right versions
   the metadata dictionary will be expanded.
2. Use this new ec2_utils module in the cloudstack and ec2
   datasources as there entrypoints into boto.

1 files changed, 65 insertions, 0 deletions

diff --git a/cloudinit/ec2_utils.py b/cloudinit/ec2_utils.py
new file mode 100644
index 00000000..76699102
--- /dev/null
+++ b/cloudinit/ec2_utils.py
@@ -0,0 +1,65 @@
+# vi: ts=4 expandtab
+#
+#    Copyright (C) 2012 Yahoo! Inc.
+#
+#    Author: Joshua Harlow <harlowja@yahoo-inc.com>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License version 3, as
+#    published by the Free Software Foundation.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import pkg_resources
+from pkg_resources import parse_version
+
+import cloudinit.util as util
+import cloudinit.url_helper as uh
+
+import boto.utils as boto_utils
+
+
+BOTO_LAZY = False
+try:
+    _boto_lib = pkg_resources.get_distribution('boto')
+    if _boto_lib.parsed_version > parse_version("2.5.2"):
+        BOTO_LAZY = True
+except pkg_resources.DistributionNotFound:
+    pass
+
+
+# Versions of boto >= 2.6.0 try to lazily load
+# the metadata backing, which doesn't work so well
+# in cloud-init especially since the metadata is
+# serialized and actions are performed where the
+# metadata server may be blocked (thus the datasource
+# will start failing) resulting in url exceptions
+# when fields that do exist (or would have existed)
+# do not exist due to the blocking that occurred.
+def _unlazy_dict(mp):
+    if not isinstance(mp, (dict)):
+        return mp
+    if not BOTO_LAZY:
+        return mp
+    for (k, v) in mp.items():
+        _unlazy_dict(v)
+
+
+def get_instance_userdata(api_version, metadata_address):
+    ud = boto_utils.get_instance_userdata(api_version, None, metadata_address)
+    if not ud:
+        ud = ''
+    return ud
+
+
+def get_instance_metadata(api_version, metadata_address):
+    metadata = boto_utils.get_instance_metadata(api_version, metadata_address)
+    if not isinstance(metadata, (dict)):
+        metadata = {}
+    return _unlazy_dict(metadata)