Nifi - Invalid cors request when uploading template, behind proxy

I have set up a secure NiFi instance (with keycloak) in docker behind proxy. Although everything works as expected when I try to upload a template NiFi gives me "invalid cors request" error and in developer tools I get 403 unauthorized. If i try to upload the template through the server:port it works fine. Does anyone have any idea how to solve this?

I already tried some headers in apache directives but as fas as i can understand the problem is not the cors error but the 403 unauthorized.

I followed these these steps in order to integrate NiFi with keycloak.

Thank you for your time and effort!

Solution

For anyone that might face this issue in the future. The error indicates that the request is not authorized behind proxy - Ngnix cant authorize the request (from NiFi was authorized) .

I was able to fix this by adding these to my apache directives section:

ProxyPreserveHost       On
ProxyRequests           Off
AllowEncodedSlashes     NoDecode
RequestHeader set X-Forwarded-Proto "https"
RequestHeader set X-Forwarded-Port "443"