Enabling CORS in a Cloud 9 service

Question

I'm using a C9 AWS instance to run an API REST written in ruby on rails, and i'm consuming the resources from an Ionic App with simple http calls. When i make a http request from the ionic app, the server response with this message: Failed to load https://the_server.vfs.cloud9.us-east-2.amazonaws.com/resource: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8100' is therefore not allowed access. The response had HTTP status code 404. How can I enable the CORS in the Cloud 9 instance ?

I have already enable the CORS in rails with the rack-cors gem

Answer 1

The call to https://the_server.vfs.cloud9.us-east-2.amazonaws.com/resource is being handled by a proxy. To allow CORS, you need to call the server directly. You can do that by connecting to the server IP address, and opening the correct ports. It's described here: https://docs.aws.amazon.com/cloud9/latest/user-guide/app-preview.html?icmpid=docs_ac9_ide#app-preview-share