[ADD] add upstream tmpl

hack/contrib/docker/gateway/nginxtmp/tmpl/upstreams-http-rbd.tmpl

@@ -0,0 +1,25 @@
+{{ range $upstream := . }}
+    upstream {{$upstream.Name}} {
+        server 0.0.0.1;
+        balancer_by_lua_block {
+            local balancer = require "ngx.balancer"
+            local cjson = require("cjson")
+
+            local endpoints = cjson.decode(ngx.shared.upstreams_dict:get("{{$upstream.Name}}"))
+            local endpoint = endpoints[math.random(1,table.getn(endpoints))]
+
+            balancer.set_timeouts(1, 0.5, 0.5)
+            balancer.set_more_tries(2)
+
+            local ok, err = balancer.set_current_peer(
+                endpoint.Host, endpoint.Port
+            )
+
+            if not ok then
+                ngx.log(ngx.ERR, "failed to set peer: ", err)
+                return ngx.exit(500)
+            end
+        }
+        keepalive 10;
+    }
+{{ end }}