Adds option to set custom data buffer dir

Implements blueprint custom-disk-buffer

When pushing an image large enough to be chunked into either a Swift
or S3 backend, the chunks are buffered to /tmp.

This change allows a user to define an alternate directory via the
configuration files.

Change-Id: I2660b6e5a76cbfd43834384b129550b66bb9afce

doc/source/configuring.rst

@@ -332,6 +332,18 @@ Glance write chunks to Swift? This amount of data is written
 to a temporary disk buffer during the process of chunking
 the image file, and the default is 200MB
 
+* ``swift_store_object_buffer_dir=PATH``
+
+Optional. Default: ``the platform's default temporary directory``
+
+Can only be specified in configuration files.
+
+`This option is specific to the Swift storage backend.`
+
+When sending large images to Swift, what directory should be
+used to buffer the chunks? By default the platform's
+temporary directory will be used.
+
 Configuring the S3 Storage Backend
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -408,6 +420,18 @@ Can only be specified in configuration files.
 If true, Glance will attempt to create the bucket ``s3_store_bucket``
 if it does not exist.
 
+* ``s3_store_object_buffer_dir=PATH``
+
+Optional. Default: ``the platform's default temporary directory``
+
+Can only be specified in configuration files.
+
+`This option is specific to the S3 storage backend.`
+
+When sending images to S3, what directory should be
+used to buffer the chunks? By default the platform's
+temporary directory will be used.
+
 Configuring the RBD Storage Backend
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

etc/glance-api.conf

@@ -130,6 +130,11 @@ swift_store_large_object_chunk_size = 200
 # Ex. https://example.com/v1.0/ -> https://snet-example.com/v1.0/
 swift_enable_snet = False
 
+# When sending large images to Swift, the chunks will be written to a
+# temporary buffer on disk. By default the platform's temporary directory
+# will be used. If required, an alternative directory can be specified here.
+# swift_store_object_buffer_dir = /path/to/dir
+
 # ============ S3 Store Options =============================
 
 # Address where the S3 authentication service lives
@@ -153,6 +158,11 @@ s3_store_bucket = <lowercased 20-char aws access key>glance
 # Do we create the bucket if it does not exist?
 s3_store_create_bucket_on_put = False
 
+# When sending images to S3, the data will first be written to a
+# temporary buffer on disk. By default the platform's temporary directory
+# will be used. If required, an alternative directory can be specified here.
+# s3_store_object_buffer_dir = /path/to/dir
+
 # ============ RBD Store Options =============================
 
 # Ceph configuration file path

glance/store/s3.py

@@ -210,6 +210,12 @@ class Store(glance.store.base.Store):
         else:  # Defaults http
             self.full_s3_host = 'http://' + self.s3_host
 
+        if self.options.get('s3_store_object_buffer_dir'):
+            self.s3_store_object_buffer_dir = self.options.get(
+                's3_store_object_buffer_dir')
+        else:
+            self.s3_store_object_buffer_dir = None
+
     def _option_get(self, param):
         result = self.options.get(param)
         if not result:
@@ -325,8 +331,9 @@ class Store(glance.store.base.Store):
         msg = _("Writing request body file to temporary file "
                 "for %s") % loc.get_uri()
         logger.debug(msg)
-        temp_file = tempfile.NamedTemporaryFile()
 
+        tmpdir = self.s3_store_object_buffer_dir
+        temp_file = tempfile.NamedTemporaryFile(dir=tmpdir)
         checksum = hashlib.md5()
         chunk = image_file.read(self.CHUNKSIZE)
         while chunk:

glance/store/swift.py

@@ -215,6 +215,12 @@ class Store(glance.store.base.Store):
                     ) * (1024 * 1024)  # Size specified in MB in conf files
             else:
                 self.large_object_chunk_size = DEFAULT_LARGE_OBJECT_CHUNK_SIZE
+
+            if self.options.get('swift_store_object_buffer_dir'):
+                self.swift_store_object_buffer_dir = (
+                    self.options.get('swift_store_object_buffer_dir'))
+            else:
+                self.swift_store_object_buffer_dir = None
         except Exception, e:
             reason = _("Error in configuration options: %s") % e
             logger.error(reason)
@@ -359,8 +365,9 @@ class Store(glance.store.base.Store):
                 total_chunks = int(math.ceil(
                     float(image_size) / float(self.large_object_chunk_size)))
                 checksum = hashlib.md5()
+                tmp = self.swift_store_object_buffer_dir
                 while bytes_left > 0:
-                    with tempfile.NamedTemporaryFile() as disk_buffer:
+                    with tempfile.NamedTemporaryFile(dir=tmp) as disk_buffer:
                         chunk_size = min(self.large_object_chunk_size,
                                          bytes_left)
                         logger.debug(_("Writing %(chunk_size)d bytes for "