propagate X-Forwarded-Proto header

docker/rootfs/etc/nginx/conf.d/include/force-ssl.conf

@@ -2,8 +2,8 @@ set $test "";
 if ($scheme = "http") {
 	set $test "H";
 }
-if ($http_x_forwarded_proto = "http") {
-	set $test "H";
+if ($http_x_forwarded_proto = "https") {
+	set $test "";
 }
 if ($request_uri = /.well-known/acme-challenge/test-challenge) {
 	set $test "${test}T";

docker/rootfs/etc/nginx/conf.d/include/proxy.conf

@@ -1,7 +1,13 @@
 add_header       X-Served-By $host;
 proxy_set_header Host $host;
-proxy_set_header X-Forwarded-Scheme $scheme;
-proxy_set_header X-Forwarded-Proto  $scheme;
+
+set $origin_scheme $scheme;
+if ($http_x_forwarded_proto != "") {
+	set $origin_scheme $http_x_forwarded_proto;
+}
+proxy_set_header X-Forwarded-Scheme $origin_scheme;
+proxy_set_header X-Forwarded-Proto  $origin_scheme;
+
 proxy_set_header X-Forwarded-For    $proxy_add_x_forwarded_for;
 proxy_set_header X-Real-IP          $remote_addr;
 proxy_pass       $forward_scheme://$server:$port$request_uri;