400 is usually for a malformed request. It seems like in this case the request is well formed, it's just not allowed. 403 seems reasonable if the user isn't authorized to make a request to the URL, which they aren't. Some APIs return redirects which also seems pretty reasonable.
But that also implies that some user would be authorized to make a request to the HTTP port (or that the resource does exist, which in this case it doesn’t).
IMO, 400 is more accurate, but really either could be acceptable, so long as the client is notified of the error. But, I wouldn’t automatically redirect the client. That’s what we are trying to avoid.
I guess this might depend a little on the implementation. In some cases the http endpoint may exist but may only be accessible to a sidecar container via localhost. For example, if the sidecar terminates https.
