From 47cf2132a27f85cccf779f070badc3cebbc37a3c Mon Sep 17 00:00:00 2001
From: Tomas Sedovic <tomas@sedovic.cz>
Date: Thu, 3 May 2012 16:19:17 +0200
Subject: [PATCH] Connect cfn utils to the remote server

The cfn_helper's `Metadata` class can now connect to the metadata server
prodived it's URL is known and available.

Engine will pass metadata server's URL via the User Data to the following file:

    /var/lib/cloud/data/cfn-metadata-server

If the file doesn't exist or the server is unreachable, cfntools will read
metadata from the `/var/lib/cloud/data/cfn-init-data` file as they did so far.

Note that Engine dosen't currently know the metadata server's URL so it's not
passing it to the instance yet.
---
 heat/cfntools/cfn_helper.py | 43 +++++++++++++++++++++++++++++++++----
 heat/engine/instance.py     | 10 +++++++--
 heat/engine/parser.py       |  3 ++-
 3 files changed, 49 insertions(+), 7 deletions(-)

diff --git a/heat/cfntools/cfn_helper.py b/heat/cfntools/cfn_helper.py
index 24bfbb9d..b35287ad 100644
--- a/heat/cfntools/cfn_helper.py
+++ b/heat/cfntools/cfn_helper.py
@@ -41,7 +41,8 @@ import rpmUtils.updates as rpmupdates
 import rpmUtils.miscutils as rpmutils
 import subprocess
 import sys
-
+from urllib2 import urlopen
+from urlparse import urlparse, urlunparse
 
 def to_boolean(b):
     val = b.lower().strip() if isinstance(b, basestring) else b
@@ -731,6 +732,8 @@ class ServicesHandler(object):
             else:
                 self._monitor_services(handler, service_entries)
 
+class MetadataServerConnectionError(Exception):
+    pass
 
 class Metadata(object):
     _metadata = None
@@ -750,6 +753,35 @@ class Metadata(object):
         self._is_local_metadata = True
         self._metadata = None
 
+
+    def metadata_server_url(self):
+        """
+        Return the url to the metadata server.
+        """
+        try:
+            f = open("/var/lib/cloud/data/cfn-metadata-server")
+            server_url = f.read()
+            f.close()
+        except IOError:
+            return None
+
+        url_parts = list(urlparse(server_url))
+        url_parts[2] = '/stacks/%s/resources/%s' % (self.stack, self.resource)
+        return urlunparse(url_parts)
+
+    def remote_metadata(self):
+        """
+        Connect to the metadata server and retreive the metadata from there.
+        """
+        server_url = self.metadata_server_url()
+        if not server_url:
+            raise MetadataServerConnectionError()
+
+        try:
+            return urlopen(server_url).read()
+        except:
+            raise MetadataServerConnectionError()
+
     def retrieve(self, meta_str=None):
         """
         Read the metadata from the given filename
@@ -757,9 +789,12 @@ class Metadata(object):
         if meta_str:
             self._data = meta_str
         else:
-            f = open("/var/lib/cloud/data/cfn-init-data")
-            self._data = f.read()
-            f.close()
+            try:
+                self._data = self.remote_metadata()
+            except MetadataServerConnectionError:
+                f = open("/var/lib/cloud/data/cfn-init-data")
+                self._data = f.read()
+                f.close()
 
         if isinstance(self._data, str):
             self._metadata = json.loads(self._data)
diff --git a/heat/engine/instance.py b/heat/engine/instance.py
index bd3fc8db..951a38ed 100644
--- a/heat/engine/instance.py
+++ b/heat/engine/instance.py
@@ -108,13 +108,19 @@ class Instance(Resource):
                            filename='cfn-init-data')
             mime_blob.attach(msg)
 
+            if self.stack.metadata_server:
+                msg = MIMEText(self.stack.metadata_server,
+                               _subtype='x-cfninitdata')
+                msg.add_header('Content-Disposition', 'attachment',
+                               filename='cfn-metadata-server')
+                mime_blob.attach(msg)
+
             msg = MIMEText(userdata, _subtype='x-shellscript')
             msg.add_header('Content-Disposition', 'attachment', filename='startup')
             mime_blob.attach(msg)
             self.mime_string = mime_blob.as_string()
-        
-        return self.mime_string
 
+        return self.mime_string
 
     def create(self):
         def _null_callback(p, n, out):
diff --git a/heat/engine/parser.py b/heat/engine/parser.py
index 4f30c6c2..a1370317 100644
--- a/heat/engine/parser.py
+++ b/heat/engine/parser.py
@@ -48,7 +48,8 @@ class Stack(object):
         self.doc = None
         self.name = stack_name
         self.parsed_template_id = 0
-        self.metadata_server = 'http://10.0.0.1'
+        # TODO(shadower) load this from a config file
+        #self.metadata_server = 'http://10.0.0.1'
 
         self.parms['AWS::StackName'] = {"Description": "AWS StackName",
             "Type": "String",
-- 
2.45.2