Start allowing different merging types to be applied

After user data handling splits apart all the different
content types into there various mime messages it is
nice to be able to have each message specify how it should
be merged (mainly for cloud-config or cloud-archive) into
the single cloud config that is eventually used. This 
starts to add a plugable merging framework and the
needed components to activate said headers and merging.

1 files changed, 10 insertions, 12 deletions

diff --git a/cloudinit/handlers/cloud_config.py b/cloudinit/handlers/cloud_config.py
index f6d95244..86027187 100644
--- a/cloudinit/handlers/cloud_config.py
+++ b/cloudinit/handlers/cloud_config.py
@@ -22,6 +22,7 @@
 
 from cloudinit import handlers
 from cloudinit import log as logging
+from cloudinit import mergers
 from cloudinit import util
 
 from cloudinit.settings import (PER_ALWAYS)
@@ -31,8 +32,8 @@ LOG = logging.getLogger(__name__)
 
 class CloudConfigPartHandler(handlers.Handler):
     def __init__(self, paths, **_kwargs):
-        handlers.Handler.__init__(self, PER_ALWAYS)
-        self.cloud_buf = []
+        handlers.Handler.__init__(self, PER_ALWAYS, version=3)
+        self.cloud_buf = {}
         self.cloud_fn = paths.get_ipath("cloud_config")
 
     def list_types(self):
@@ -43,20 +44,17 @@ class CloudConfigPartHandler(handlers.Handler):
     def _write_cloud_config(self, buf):
         if not self.cloud_fn:
             return
-        lines = [str(b) for b in buf]
-        payload = "\n".join(lines)
+        payload = util.yaml_dumps(self.cloud_buf)
         util.write_file(self.cloud_fn, payload, 0600)
 
-    def _handle_part(self, _data, ctype, filename, payload, _frequency):
+    def handle_part(self, _data, ctype, filename, payload, _frequency, headers):
         if ctype == handlers.CONTENT_START:
-            self.cloud_buf = []
+            self.cloud_buf = {}
             return
         if ctype == handlers.CONTENT_END:
             self._write_cloud_config(self.cloud_buf)
-            self.cloud_buf = []
+            self.cloud_buf = {}
             return
-
-        filename = util.clean_filename(filename)
-        if not filename:
-            filename = '??'
-        self.cloud_buf.extend(["#%s" % (filename), str(payload)])
+        merge_how = headers.get("Merge-Type", 'list+dict+str')
+        merger = mergers.construct(merge_how)
+        self.cloud_buf = merger.merge(self.cloud_buf, util.load_yaml(payload))