Add CORS support for python as well as ability to upload files.

[vallard]

My application in python needed to support CORS. I added this. In addition I needed to be able to upload files with HTML forms. Adding the files to the event allows this to happen to make this a more useful runtime.

[andresmgot]

Hi @vallard,

Thank you for the PR! I have sent a couple of comments, please take a look.

[andresmgot]

For consistency with the rest of runtimes we should not modify the event structure (which is documented here. If you want to access the files helper (which is only present in python) you can still access it trough event.extensions.request.files.

[andresmgot]

I would suggest to do the opposite, return CORS headers if the method is OPTIONS. We can mimic what is currently being done in the nodejs runtime.

Something like (untested code, please test this):

def enable_cors(req, fn):
    def _enable_cors(*args, **kwargs):
        # set CORS headers
        bottle.response.headers['Access-Control-Allow-Origin'] = '*'

        if bottle.request.method != 'OPTIONS':
            bottle.response.headers['Access-Control-Allow-Methods'] = req.get_header('access-control-request-method')
            bottle.response.headers['Access-Control-Allow-Headers'] = req.get_header('access-control-request-headers')
        else:
            # actual request; reply with the actual response
            return fn(*args, **kwargs)

    return _enable_cors

Note that we are allowing any method and header from the request, that way we avoid having to chose the base image if there is a new method/header that we want to allow.

[meseta]

it is already possible to deal with files uploads using bottle's request instance:

from bottle import request

def your_endpoint(*args):

  uploaded = request.files.get("data")
  file_contents = uploaded.file.read()
  ...