Add more information on Forward-XXX headers and subpath config for on-premise installations

content/en/docs/deployment/general/deployment-location.md

@@ -19,12 +19,55 @@ For apps deployed to Mendix Cloud, you can customize a URL by adding [custom dom
 
 If you specify an app URL location on a (sub)path, the Mendix runtime needs to know the public URL of your application. This can be done by setting the [custom runtime setting](/refguide/custom-settings/#applicationrooturl-section) `ApplicationRootUrl`.
 
+When hosting a Mendix application on a subpath, the proxy needs to forward the request from `https://subdomain.domain/my/sub/path` to the internal address where the Mendix runtime is running. Refer to the code snippet below for an example Nginx Nginx configuration.
+
+```
+# Location block for the subpath "/my/sub/path".
+
+location /my/sub/path/ {
+
+    # Make the Mendix runtime aware of https, see documentation below for more information.
+    proxy_set_header X-Forwarded-Proto "https";
+
+    # Forward the host to the Mendix runtime.
+    proxy_set_header X-Forwarded-Host $host;
+
+    # Forward the prefix `/my/sub/path` to the Mendix runtime.
+    proxy_set_header X-Forwarded-Prefix /my/sub/path;
+
+    # Optional: forward a port when not running on standard ports.
+    # proxy_set_header X-Forwarded-Port 3000;
+
+    # Required for Mendix DevTools to work.
+    proxy_http_version 1.1;
+
+    # Proxy the request to the Mendix runtime.
+    proxy_pass http://mendix-runtime:8080/;
+}
+```
+
 {{% alert color="info" %}}
 Routing based on a subpath is possible as of Studio Pro 10.3 (for details, see the [ApplicationRootUrl](/refguide/custom-settings/#applicationrooturl-section) section of the *Runtime Customization* page), although it is not supported in Mendix Cloud. For versions below 10.3, it is not possible to use a path to your app. Your app should always be at the root of your subdomain. In other words, it should be at a location like this: `https://subdomain.domain/`.
 
 If you want to deploy several apps on the same domain, use different subdomains to identify the app. For example, use `https://appA.apps.mydomain.com/`, not `https://mydomain.com/apps/appA`.
 {{% /alert %}}
 
+## Secure Cookies for On-Premise Applications
+
+The Mendix runtime automatically sets cookies with the `secure` attribute when applications are served over HTTPS. However, when deploying a Mendix application behind a load balancer that uses HTTP for internal communication, additional configuration is required.
+
+In this case, the Mendix runtime must be explicitly informed that end-users are accessing the application via HTTPS. This can be done through either of these methods:
+
+* Configure the [ApplicationRootUrl](/refguide/custom-settings/#applicationrooturl-section) runtime setting with an `https://` URL
+* Set the `X-Forwarded-Proto` or `X-Forwarded-Schema` header to `https` in the loadbalancer.
+
+{{% alert color="info" %}}
+
+* For Mendix versions prior to Mendix 10.18, setting the [ApplicationRootUrl](/refguide/custom-settings/#applicationrooturl-section) runtime setting to an `https://` URL will not make the application aware of it being served via HTTPS. You must use the `X-Forwarded-Proto` and `X-Forwarded-Schema` headers instead.
+
+* For Mendix versions 10.18 and later, setting the [ApplicationRootUrl](/refguide/custom-settings/#applicationrooturl-section) runtime setting to an `http://` URL will take precedence over the `X-Forwarded-Proto` and `X-Forwarded-Schema` headers.
+{{% /alert %}}
+
 ## Main Domain Name
 
 Do not deploy your app directly at the apex domain (`https://domain/`).