This simple script will change/update the Content-Type for all objects in our Rackspace Cloud Files container.

cf_update_content_type_by_ext.py

#!/usr/bin/python
import os
import pyrax

YOUR_USERNAME=""
YOUR_API_KEY=""
YOUR_REGION=""  # E.g., "ORD", "DFW", etc.
YOUR_CONTAINER_NAME=""

#pyrax.set_setting('identity_type', 'rackspace')
pyrax.set_credentials(YOUR_USERNAME, YOUR_API_KEY, region=YOUR_REGION)

cf = pyrax.connect_to_cloudfiles(public=True)

for obj in cf.get_container_object_names(YOUR_CONTAINER_NAME):
    file_name, file_extension = os.path.splitext(str(obj))
    if file_extension == '.jpg':
        cf.change_object_content_type(YOUR_CONTAINER_NAME, str(obj),
                                      "image/jpeg", guess=False)

    # Uncomment the following line if you want pyrax to try to guess the
    # the correct Content-Type (note: You will, of course, want to comment
    # out the "if file_extension" part above if you use the following line)
    #cf.change_object_content_type(YOUR_CONTAINER_NAME, str(obj), guess=True)