A patch to close upstream connections on setting the "down" flag

proxy_upstream_connclose.diff

--- ./bundle/nginx-1.11.2/src/stream/ngx_stream_proxy_module.c	2017-04-06 15:55:53.000000000 +0300
+++ ./bundle/nginx-1.11.2/src/stream/ngx_stream_proxy_module.c	2017-04-08 22:50:56.000000000 +0300
@@ -1,4 +1,3 @@
-
 /*
  * Copyright (C) Roman Arutyunyan
  * Copyright (C) Nginx, Inc.
@@ -1152,6 +1151,10 @@
     ngx_log_handler_pt            handler;
     ngx_stream_upstream_t        *u;
     ngx_stream_proxy_srv_conf_t  *pscf;
+    ngx_stream_upstream_srv_conf_t *uscf;
+    ngx_stream_upstream_rr_peers_t *peers;
+    ngx_stream_upstream_rr_peer_t *peer;
+    ngx_uint_t                    i;

     u = s->upstream;

@@ -1174,6 +1177,35 @@
     }

     pscf = ngx_stream_get_module_srv_conf(s, ngx_stream_proxy_module);
+    uscf = pscf->upstream;
+
+    peers = uscf->peer.data;
+
+    if (peers != NULL) {
+      for (i = 0; i < peers->number; i++) {
+        peer = &peers->peer[i];
+
+        if (peer->down && &peer->name == u->peer.name) {
+          ngx_log_error(NGX_LOG_ERR, c->log, 0, "Closing connection to %V", &peer->name);
+          ngx_stream_proxy_finalize(s, NGX_DECLINED);
+          return;
+        }
+      }
+
+      peers = peers->next;
+
+      if (peers != NULL) {
+        for (i = 0; i < peers->number; i++) {
+          peer = &peers->peer[i];
+
+          if (peer->down && &peer->name == u->peer.name) {
+            ngx_log_error(NGX_LOG_ERR, c->log, 0, "Closing connection to %V", &peer->name);
+            ngx_stream_proxy_finalize(s, NGX_DECLINED);
+            return;
+          }
+        }
+      }
+    }

     if (from_upstream) {
         src = pc;