Add additional builder debug logging

Tracking down builder decisions to do (or not do) things is made
difficult by not having insight into certain data. Particularly,
the upload recency table is used to determine whether or not images
should be deleted from a provider. Having that data in debug logs
helps tremendously.

We also log when we delete the upload znode record and remove the
'stats' portion of ImageUpload str representation because it turns
out to not be as useful as I had hoped in the beginning.

Change-Id: Ic6e1ea0811879ed8eaf0216ef2a3b68e9380e727

nodepool/builder.py

@@ -192,6 +192,8 @@ class CleanupWorker(BaseWorker):
                 self._rtable[i][p].sort(key=lambda x: x[2], reverse=True)
                 self._rtable[i][p] = self._rtable[i][p][:2]
 
+        self.log.debug("Upload recency table: %s", self._rtable)
+
     def _isRecentUpload(self, image, provider, build_id, upload_id):
         '''
         Search for an upload for a build within the recency table.
@@ -322,6 +324,7 @@ class CleanupWorker(BaseWorker):
                     "Unable to delete image %s from %s:",
                     upload.external_name, upload.provider_name)
             else:
+                self.log.debug("Deleting image upload: %s", upload)
                 self._zk.deleteUpload(upload.image_name, upload.build_id,
                                       upload.provider_name, upload.id)
 

nodepool/zk.py

@@ -284,7 +284,6 @@ class ImageUpload(BaseModel):
         d['provider_name'] = self.provider_name
         d['image_name'] = self.image_name
         d['format'] = self.format
-        d['stat'] = self.stat
         return '<ImageUpload %s>' % d
 
     def __eq__(self, other):