In addition to condictions for bucket, key, and acl, the policy document must contain rules for name, Filename, and success_action_status. For instance:
["starts-with", "$name", ""],
["starts-with", "$Filename", ""],
["starts-with", "$success_action_status", ""],
Filename
is a field that the Flash backend sends, but the HTML5 backend does not.
The multipart
setting must be True, but that is the default these days.
The multipart_params
setting must be a dictionary with the following fields:
key
AWSAccessKeyId
acl = 'private'
policy
signature
success_action_status = '201'
Setting success_action_status
to 201 causes S3 to return an XML document with HTTP status code 201. This is necessary to make the flash backend work. (The flash upload stalls when the response is empty and the code is 200 or 204. It results in an I/O error if the response is a redirect.)
S3 does not understand chunks, so remove the chunk_size
config option.
unique_names
can be either True or False, both work.