Only HTTPS redirect for a specific host (the one with a valid cert)

Currently the HTTPS redirection middleware always redirects to HTTPS, however this breaks stuff when the host is not the one for which the certificate has been issued or in my case when there is no certificate because the SSL termination has happened two proxies higher up.

For example, running an ASP.NET Core app hosted in Kubernetes means that there is normally 2 proxies in front of Kestrel. One is the ingress controller, which is normally configured to use a Let's Encrypt certificate and is doing the SSL termination and then a second proxy is an internal service load balancer in front of all the pods where the apps are running.

Kubernetes checks the health of a pod by doing readiness and liveness checks, but these are being done via the internal network on a local IP address (e.g. http://10.8.0.7/healthz). If the HTTPS redirect middleware is enabled then it will try to redirect this request to https://10.8.0.7/healthz, which cannot be resolved and the service will fail the health check and get subsequently killed.

Currently one can apply a workaround fix by specifying the X-Forwarded-Proto header for the health check inside Kubernetes, which will prevent the middleware from redirecting, but that only works in some instances. Other cloud infrastructure and 3rd party services which cannot be configured to send the X-Forwarded-Proto header will still fail to health check the service.

This could be easily prevented by configuring a list of hosts for which the https redirection middleware will redirect, otherwise not.

Currently I have to run a custom middleware before the https redirection middleware and check the host and then based on the host decide if I set the Request.Scheme to https or not in order to workaround this issue, but it would be nicer if this could be configured in one middleware.

Any thoughts?

EDIT:

Basically what I want to do is to give the HTTPS redirect middleware a list of hosts for which it should redirect to https, otherwise do nothing:

- `api.example.org`
- `www.example.org`
- `example.org`

otherwise don't redirect.