mod_http_upload: Add Nginx configuration snippet

Include an example configuration snippet that shows how to tell Nginx to

1) proxy the HTTP PUT requests to mod_http_upload, and to
2) serve the HTTP GET requests directly.

mod_http_upload/examples/nginx-upload.conf

@@ -0,0 +1,25 @@
+server {
+    listen *:443 ssl;
+    server_name upload.example.com;
+    ssl_certificate /path/to/upload.example.com.crt;
+    ssl_certificate_key /path/to/upload.example.com.key;
+
+    # The `docroot' used by mod_http_upload.
+    root /home/xmpp/upload;
+
+    # Shouldn't be smaller than the `max_size' accepted by mod_http_upload.
+    client_max_body_size 100m;
+
+    location / {
+        # Pass all requests to ejabberd, except for GET and HEAD requests.
+        limit_except GET {
+            proxy_pass http://localhost:5444;
+        }
+        proxy_set_header Host $host;
+
+        if ($request_method = GET) {
+            add_header X-Frame-Options DENY;
+        }
+        add_header Strict-Transport-Security "max-age=31536000";
+    }
+}