Python flask: forward POST to external API - redirect

Question

I am building a microservice for the Camunda rest API using python flask and flask_restplus, python 3.7.0. Camunda is running in a docker container, available via localhost, port 8080. All GET requests to my microservice are being forwarded to the Camunda API via redirect, which is working perfectly fine.
POST requests (tested via postman, as suggested in the official tutorial) are not being forwarded properly using
redirect(camunda_api_url)
or
request.post(camunda_api_url)
The POST request via postman is done using
Header: Content-Type: multipart/form-data
Body: upload File Object (somefile.bpmn)
When I do the POST to the Camunda REST-API directly, everything works just fine, but when I try to redirect my post via my microservice, I get status code 200, but the file isn't being uploaded.
Debugging at my endpoint I can see that the file is being received:
print(request.files['upload'])
<FileStorage: 'somefile.bpmn' ('application/octet-stream')>
Thus the file is being transmitted successfully, but the redirect doesn't work.
My endpoint method looks like this:
def post(self):
print(request.files['upload'])
test = requests.post(host_prefix + 'deployment/create', files=request.files)
print(test.status_code)
Modifying the request.post via
data=request.files
data=request.files['upload']
or omiting data completely
always results in the file not being uploaded.
Trying redirect via
redirect(host_prefix + 'deployment/create', code=307)
also results in the file not being uploaded.
How can I redirect this post request properly to the Camunda API ?
This is not a question about the Camunda API rather than how to redirect a POST request to a foreign endpoint properly.
P.S.: I created my api and endpoints like this:
app = Flask(__name__)
api = Api(app, version='0.1', title='BPMN-API', description='A BPMN-API for Camunda, implemented in python')
...
api.add_resource(CreateDeployment, api_prefix + 'deployment/create', methods=['POST'])

Answer 1

OK, I solved this problem by using:
requests.post(camunda_api_url, files={file_name:request.files['upload'].read()})
where camunda_api_url is the endpoint at the Camunda REST engine, file_name is the name of the file being uploaded, AND by adding a
get-method,using simply:
def get(self):
camunda_api_url = "http://localhost:8080/engine-rest/deployment/create"
return redirect(camunda_api_url)
Without the get method the post doesn't work.
-> setting topic to solved. :)

Answer 2

By using requests library it is very easy. The example shows multiple file uploads with same key and with other form data as well. The images are coming from a form with the key named 'images'
The example gets file list from a form with the key 'images' and forward that files to another URL or API.
images = request.files.getlist('images')
files = []
for image in images:
files.append(("images", (image.filename, image.read(), image.content_type)))
r = requests.post(url=api_urls.insert_face_data_url, data={"apikey": apikey, "faceid": faceid},
files=files)