diff --git a/b_gdb b/b_gdb
new file mode 100644
index 0000000..24e2bf5
--- /dev/null
+++ b/b_gdb
@@ -0,0 +1,5 @@
+break ngx_http_lua_upstream_get_upstreams
+break ngx_http_lua_upstream_get_upstream_main_conf
+break ngx_http_lua_upstream_get_servers
+break ngx_http_lua_upstream_find_upstream
+break ngx_http_lua_upstream_add_server
diff --git a/nginx.12085.conf b/nginx.12085.conf
new file mode 100644
index 0000000..57f0520
--- /dev/null
+++ b/nginx.12085.conf
@@ -0,0 +1,123 @@
+
+#user  nobody;
+worker_processes  1;
+
+#error_log  logs/error.log;
+#error_log  logs/error.log  notice;
+#error_log  logs/error.log  info;
+
+#pid        logs/nginx.pid;
+
+
+events {
+    worker_connections  1024;
+}
+
+# load modules compiled as Dynamic Shared Object (DSO)
+#
+#dso {
+#    load ngx_http_fastcgi_module.so;
+#    load ngx_http_rewrite_module.so;
+#}
+
+http {
+    include       mime.types;
+    default_type  application/octet-stream;
+
+    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
+                      '$status $body_bytes_sent "$http_referer" '
+                      '"$http_user_agent" "$http_x_forwarded_for"';
+
+    #access_log  logs/access.log  main;
+
+    sendfile        on;
+    #tcp_nopush     on;
+
+    #keepalive_timeout  0;
+    keepalive_timeout  65;
+
+    #gzip  on;
+
+    server {
+        listen       12085;
+        server_name  localhost;
+
+        #charset koi8-r;
+
+        access_log  logs/12085.host.access.log  main;
+
+        location / {
+            root   html;
+            index  index.html index.htm;
+        }
+
+        #error_page  404              /404.html;
+
+        # redirect server error pages to the static page /50x.html
+        #
+        error_page   500 502 503 504  /50x.html;
+        location = /50x.html {
+            root   html;
+        }
+
+        # proxy the PHP scripts to Apache listening on 127.0.0.1:80
+        #
+        #location ~ \.php$ {
+        #    proxy_pass   http://127.0.0.1;
+        #}
+
+        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
+        #
+        #location ~ \.php$ {
+        #    root           html;
+        #    fastcgi_pass   127.0.0.1:9000;
+        #    fastcgi_index  index.php;
+        #    fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
+        #    include        fastcgi_params;
+        #}
+
+        # deny access to .htaccess files, if Apache's document root
+        # concurs with nginx's one
+        #
+        #location ~ /\.ht {
+        #    deny  all;
+        #}
+    }
+
+
+    # another virtual host using mix of IP-, name-, and port-based configuration
+    #
+    #server {
+    #    listen       8000;
+    #    listen       somename:8080;
+    #    server_name  somename  alias  another.alias;
+
+    #    location / {
+    #        root   html;
+    #        index  index.html index.htm;
+    #    }
+    #}
+
+
+    # HTTPS server
+    #
+    #server {
+    #    listen       443 ssl;
+    #    server_name  localhost;
+
+    #    ssl_certificate      cert.pem;
+    #    ssl_certificate_key  cert.key;
+
+    #    ssl_session_cache    shared:SSL:1m;
+    #    ssl_session_timeout  5m;
+
+    #    ssl_ciphers  HIGH:!aNULL:!MD5;
+    #    ssl_prefer_server_ciphers  on;
+
+    #    location / {
+    #        root   html;
+    #        index  index.html index.htm;
+    #    }
+    #}
+
+}
diff --git a/nginx.12086.conf b/nginx.12086.conf
new file mode 100644
index 0000000..09581f3
--- /dev/null
+++ b/nginx.12086.conf
@@ -0,0 +1,123 @@
+
+#user  nobody;
+worker_processes  1;
+
+#error_log  logs/error.log;
+#error_log  logs/error.log  notice;
+#error_log  logs/error.log  info;
+
+#pid        logs/nginx.pid;
+
+
+events {
+    worker_connections  1024;
+}
+
+# load modules compiled as Dynamic Shared Object (DSO)
+#
+#dso {
+#    load ngx_http_fastcgi_module.so;
+#    load ngx_http_rewrite_module.so;
+#}
+
+http {
+    include       mime.types;
+    default_type  application/octet-stream;
+
+    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
+                      '$status $body_bytes_sent "$http_referer" '
+                      '"$http_user_agent" "$http_x_forwarded_for"';
+
+    #access_log  logs/access.log  main;
+
+    sendfile        on;
+    #tcp_nopush     on;
+
+    #keepalive_timeout  0;
+    keepalive_timeout  65;
+
+    #gzip  on;
+
+    server {
+        listen       12086;
+        server_name  localhost;
+
+        #charset koi8-r;
+
+        access_log  logs/12086.host.access.log  main;
+
+        location / {
+            root   html;
+            index  index.html index.htm;
+        }
+
+        #error_page  404              /404.html;
+
+        # redirect server error pages to the static page /50x.html
+        #
+        error_page   500 502 503 504  /50x.html;
+        location = /50x.html {
+            root   html;
+        }
+
+        # proxy the PHP scripts to Apache listening on 127.0.0.1:80
+        #
+        #location ~ \.php$ {
+        #    proxy_pass   http://127.0.0.1;
+        #}
+
+        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
+        #
+        #location ~ \.php$ {
+        #    root           html;
+        #    fastcgi_pass   127.0.0.1:9000;
+        #    fastcgi_index  index.php;
+        #    fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
+        #    include        fastcgi_params;
+        #}
+
+        # deny access to .htaccess files, if Apache's document root
+        # concurs with nginx's one
+        #
+        #location ~ /\.ht {
+        #    deny  all;
+        #}
+    }
+
+
+    # another virtual host using mix of IP-, name-, and port-based configuration
+    #
+    #server {
+    #    listen       8000;
+    #    listen       somename:8080;
+    #    server_name  somename  alias  another.alias;
+
+    #    location / {
+    #        root   html;
+    #        index  index.html index.htm;
+    #    }
+    #}
+
+
+    # HTTPS server
+    #
+    #server {
+    #    listen       443 ssl;
+    #    server_name  localhost;
+
+    #    ssl_certificate      cert.pem;
+    #    ssl_certificate_key  cert.key;
+
+    #    ssl_session_cache    shared:SSL:1m;
+    #    ssl_session_timeout  5m;
+
+    #    ssl_ciphers  HIGH:!aNULL:!MD5;
+    #    ssl_prefer_server_ciphers  on;
+
+    #    location / {
+    #        root   html;
+    #        index  index.html index.htm;
+    #    }
+    #}
+
+}
diff --git a/nginx.conf b/nginx.conf
new file mode 100644
index 0000000..99cbdc9
--- /dev/null
+++ b/nginx.conf
@@ -0,0 +1,329 @@
+
+#user  nobody;
+worker_processes  1;
+
+#error_log  logs/error.log;
+#error_log  logs/error.log  notice;
+#error_log  logs/error.log  info;
+
+#pid        logs/nginx.pid;
+
+
+events {
+    worker_connections  1024;
+}
+
+# load modules compiled as Dynamic Shared Object (DSO)
+#
+#dso {
+#    load ngx_http_fastcgi_module.so;
+#    load ngx_http_rewrite_module.so;
+#}
+
+http {
+     upstream foo.com {
+        server 127.0.0.1 fail_timeout=53 weight=4 max_fails=100;
+        server agentzh.org:81;
+    }
+
+    upstream bar {
+        server 127.0.0.1:12085;
+	#check interval=3 rise=2 fall=5 timeout=1000 type=http;
+        #check_http_send "HEAD / HTTP/1.0\r\n\r\n";
+        #check_http_expect_alive http_2xx http_3xx;
+#        server 127.0.0.1:12086;
+    }
+
+
+    include       mime.types;
+    default_type  application/octet-stream;
+
+    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
+                      '$status $body_bytes_sent "$http_referer" '
+                      '"$http_user_agent" "$http_x_forwarded_for"';
+
+    #access_log  logs/access.log  main;
+
+    sendfile        on;
+    #tcp_nopush     on;
+
+    #keepalive_timeout  0;
+    keepalive_timeout  65;
+
+    #gzip  on;
+
+    server {
+        listen       8080;
+        server_name  localhost;
+# sample output for the following /upstream interface:
+# upstream foo.com:
+#     addr = 127.0.0.1:80, weight = 4, fail_timeout = 53, max_fails = 100
+#     addr = 106.187.41.147:81, weight = 1, fail_timeout = 10, max_fails = 1
+# upstream bar:
+#
+
+location = /upstreams {
+            default_type text/plain;
+            content_by_lua '
+		
+                local concat = table.concat
+                local upstream = require "ngx.upstream"
+                local get_servers = upstream.get_servers
+                local get_upstreams = upstream.get_upstreams
+		local add_server = upstream.add_server
+
+		local hello = upstream.say_hello()
+		ngx.print(hello)
+		ngx.print("\\n")
+
+		--local err = add_server("bar","127.0.0.5:8080")
+		--ngx.print(err)
+		--ngx.print("\\n")
+
+                local us = get_upstreams()
+                for _, u in ipairs(us) do
+                    ngx.say("upstream ", u, ":")
+                    local srvs, err = get_servers(u)
+                    if not srvs then
+                        ngx.say("failed to get servers in upstream ", u)
+                    else
+                        for _, srv in ipairs(srvs) do
+                            local first = true
+                            for k, v in pairs(srv) do
+                                if first then
+                                    first = false
+                                    ngx.print("    ")
+                                else
+                                    ngx.print(", ")
+                                end
+                                if type(v) == "table" then
+                                    ngx.print(k, " = {", concat(v, ", "), "}")
+                                else
+                                    ngx.print(k, " = ", v)
+                                end
+                            end
+                            ngx.print("\\n")
+                        end
+                    end
+                end
+            ';
+        }
+	location   /get_servers {
+            	default_type text/plain;
+            	content_by_lua '
+                	local concat = table.concat
+                	local upstream = require "ngx.upstream"
+                	local get_servers = upstream.get_servers
+                	local get_upstreams = upstream.get_upstreams
+			--local add_server = upstream.add_server
+
+			local args =  ngx.req.get_uri_args()
+			local upstream_name;
+			for key, val in pairs(args) do
+                		if type(val) == "table" then
+                    			ngx.say(key, ": ", table.concat(val, ", "))
+					upstream_name = val
+                		else
+                    			ngx.say(key, ": ", val)
+					upstream_name = val
+            			end	
+			end
+
+                    	ngx.say("upstream ", upstream_name, ":")
+                    	local srvs, err = get_servers(upstream_name)
+                    	if not srvs then
+                        	ngx.say("failed to get servers in upstream ", upstream_name)
+                    	else
+                        	for _, srv in ipairs(srvs) do
+                            		local first = true
+                            		for k, v in pairs(srv) do
+                                		if first then
+                                    			first = false
+                                    			ngx.print("    ")
+                                		else
+                                    			ngx.print(", ")
+                                		end
+                                		if type(v) == "table" then
+                                    			ngx.print(k, " = {", concat(v, ", "), "}")
+                                		else
+                                    			ngx.print(k, " = ", v)
+                                		end
+                            		end
+                       			ngx.print("\\n")
+				end
+			end
+			
+
+		';
+		
+	}
+
+	location  /add_server {
+
+            	default_type text/plain;
+            	content_by_lua '
+
+                	local concat = table.concat
+                	local upstream = require "ngx.upstream"
+                	local get_servers = upstream.get_servers
+                	local get_upstreams = upstream.get_upstreams
+			local add_server = upstream.add_server
+
+			local args =  ngx.req.get_uri_args()
+			local upstream_name
+
+			upstream_name = args["upstream"]
+			local server_ip = args["ip"]
+			local server_port = args["port"]
+			local weight = 1
+			local max_fails = 10
+			local fail_timeout = 10
+
+			--for key, val in pairs(args) do
+                		--if type(val) == "table" then
+                    			--ngx.say(key, ": ", table.concat(val, ", "))
+					--upstream_name = val
+                		--else
+                    			--ngx.say(key, ": ", val)
+					--upstream_name = val
+            			--end	
+			--end
+
+                    	--ngx.say("upstream ", ":", upstream_name )
+			--ngx.say("server ", ":", server_ip..":"..server_port)
+		
+			local err = add_server("bar",server_ip..":"..server_port,weight,max_fails,fail_timeout)
+			--ngx.print(err)
+			--ngx.print("\\n----------------------------\\n")
+
+                    	local srvs, err = get_servers(upstream_name)
+                    	if not srvs then
+                        	ngx.say("failed to get servers in upstream ", upstream_name)
+                    	else
+                         	for _, srv in ipairs(srvs) do
+                            		local first = true
+                           		for k, v in pairs(srv) do
+                                		if first then
+                                    			first = false
+                                    			ngx.print("    ")
+                                		else
+                                    			ngx.print(", ")
+                                		end
+                                		if type(v) == "table" then
+                                    			ngx.print(k, " = {", concat(v, ", "), "}")
+                                		else
+                                    			ngx.print(k, " = ", v)
+                                		end
+                            		end
+                        		ngx.print("\\n")
+				end
+			end
+
+
+		';
+	}
+	location /get_primary_peers {
+            	default_type text/plain;
+            	content_by_lua '
+				
+		local upstream = require "ngx.upstream"
+            	local ljson = require "ljson"
+            	us = upstream.get_upstreams()
+            	for _, u in ipairs(us) do
+                	local peers, err = upstream.get_primary_peers(u)
+                	if not peers then
+                    		ngx.say("failed to get peers: ", err)
+                    		return
+                	end
+                	ngx.say(ljson.encode(peers))
+            	end
+		';
+	}
+	
+        #charset koi8-r;
+
+        access_log  logs/1080.host.access.log  main;
+	location /status {
+            check_status;
+
+            access_log   off;
+            #allow SOME.IP.ADD.RESS;
+            #deny all;
+        }
+
+        location / {
+		proxy_pass http://bar;
+            #root   html;
+            #index  index.html index.htm;
+        }
+
+        #error_page  404              /404.html;
+
+        # redirect server error pages to the static page /50x.html
+        #
+        error_page   500 502 503 504  /50x.html;
+        location = /50x.html {
+            root   html;
+        }
+
+        # proxy the PHP scripts to Apache listening on 127.0.0.1:80
+        #
+        #location ~ \.php$ {
+        #    proxy_pass   http://127.0.0.1;
+        #}
+
+        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
+        #
+        #location ~ \.php$ {
+        #    root           html;
+        #    fastcgi_pass   127.0.0.1:9000;
+        #    fastcgi_index  index.php;
+        #    fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
+        #    include        fastcgi_params;
+        #}
+
+        # deny access to .htaccess files, if Apache's document root
+        # concurs with nginx's one
+        #
+        #location ~ /\.ht {
+        #    deny  all;
+        #}
+    }
+
+
+    # another virtual host using mix of IP-, name-, and port-based configuration
+    #
+    #server {
+    #    listen       8000;
+    #    listen       somename:8080;
+    #    server_name  somename  alias  another.alias;
+
+    #    location / {
+    #        root   html;
+    #        index  index.html index.htm;
+    #    }
+    #}
+
+
+    # HTTPS server
+    #
+    #server {
+    #    listen       443 ssl;
+    #    server_name  localhost;
+
+    #    ssl_certificate      cert.pem;
+    #    ssl_certificate_key  cert.key;
+
+    #    ssl_session_cache    shared:SSL:1m;
+    #    ssl_session_timeout  5m;
+
+    #    ssl_ciphers  HIGH:!aNULL:!MD5;
+    #    ssl_prefer_server_ciphers  on;
+
+    #    location / {
+    #        root   html;
+    #        index  index.html index.htm;
+    #    }
+    #}
+
+}
diff --git a/src/ngx_http_lua_upstream_module.c b/src/ngx_http_lua_upstream_module.c
index 0d729f5..71f1ad4 100644
--- a/src/ngx_http_lua_upstream_module.c
+++ b/src/ngx_http_lua_upstream_module.c
@@ -24,60 +24,61 @@ static int ngx_http_lua_upstream_create_module(lua_State * L);
 static int ngx_http_lua_upstream_get_upstreams(lua_State * L);
 static int ngx_http_lua_upstream_get_servers(lua_State * L);
 static ngx_http_upstream_main_conf_t *
-    ngx_http_lua_upstream_get_upstream_main_conf(lua_State *L);
+ngx_http_lua_upstream_get_upstream_main_conf(lua_State *L);
 static int ngx_http_lua_upstream_get_primary_peers(lua_State * L);
 static int ngx_http_lua_upstream_get_backup_peers(lua_State * L);
 static int ngx_http_lua_get_peer(lua_State *L,
-    ngx_http_upstream_rr_peer_t *peer, ngx_uint_t id);
+                                 ngx_http_upstream_rr_peer_t *peer, ngx_uint_t id);
 static ngx_http_upstream_srv_conf_t *
-    ngx_http_lua_upstream_find_upstream(lua_State *L, ngx_str_t *host);
+ngx_http_lua_upstream_find_upstream(lua_State *L, ngx_str_t *host);
 static ngx_http_upstream_rr_peer_t *
-    ngx_http_lua_upstream_lookup_peer(lua_State *L);
+ngx_http_lua_upstream_lookup_peer(lua_State *L);
 static int ngx_http_lua_upstream_set_peer_down(lua_State * L);
+static int ngx_http_lua_upstream_say_hello(lua_State* L);
+static int
+ngx_http_lua_upstream_add_server(lua_State * L);
 
 
 static ngx_http_module_t ngx_http_lua_upstream_ctx = {
-    NULL,                           /* preconfiguration */
-    ngx_http_lua_upstream_init,     /* postconfiguration */
-    NULL,                           /* create main configuration */
-    NULL,                           /* init main configuration */
-    NULL,                           /* create server configuration */
-    NULL,                           /* merge server configuration */
-    NULL,                           /* create location configuration */
-    NULL                            /* merge location configuration */
+    NULL, /* preconfiguration */
+    ngx_http_lua_upstream_init, /* postconfiguration */
+    NULL, /* create main configuration */
+    NULL, /* init main configuration */
+    NULL, /* create server configuration */
+    NULL, /* merge server configuration */
+    NULL, /* create location configuration */
+    NULL /* merge location configuration */
 };
 
 
 ngx_module_t ngx_http_lua_upstream_module = {
     NGX_MODULE_V1,
-    &ngx_http_lua_upstream_ctx,  /* module context */
-    NULL,                        /* module directives */
-    NGX_HTTP_MODULE,             /* module type */
-    NULL,                        /* init master */
-    NULL,                        /* init module */
-    NULL,                        /* init process */
-    NULL,                        /* init thread */
-    NULL,                        /* exit thread */
-    NULL,                        /* exit process */
-    NULL,                        /* exit master */
+    &ngx_http_lua_upstream_ctx, /* module context */
+    NULL, /* module directives */
+
+    NGX_HTTP_MODULE, /* module type */
+    NULL, /* init master */
+    NULL, /* init module */
+    NULL, /* init process */
+    NULL, /* init thread */
+    NULL, /* exit thread */
+    NULL, /* exit process */
+    NULL, /* exit master */
     NGX_MODULE_V1_PADDING
 };
 
-
 static ngx_int_t
 ngx_http_lua_upstream_init(ngx_conf_t *cf)
 {
     if (ngx_http_lua_add_package_preload(cf, "ngx.upstream",
-                                         ngx_http_lua_upstream_create_module)
-        != NGX_OK)
-    {
+            ngx_http_lua_upstream_create_module)
+            != NGX_OK) {
         return NGX_ERROR;
     }
 
     return NGX_OK;
 }
 
-
 static int
 ngx_http_lua_upstream_create_module(lua_State * L)
 {
@@ -98,16 +99,113 @@ ngx_http_lua_upstream_create_module(lua_State * L)
     lua_pushcfunction(L, ngx_http_lua_upstream_set_peer_down);
     lua_setfield(L, -2, "set_peer_down");
 
+    lua_pushcfunction(L, ngx_http_lua_upstream_say_hello);
+    lua_setfield(L, -2, "say_hello");
+
+    lua_pushcfunction(L, ngx_http_lua_upstream_add_server);
+    lua_setfield(L, -2, "add_server");
+
+    //    lua_pushcfunction(L, ngx_http_lua_upstream_update_peer_addr);
+    //    lua_setfield(L, -2, "update_peer_addr");
+
     return 1;
 }
 
+static int
+ngx_http_lua_upstream_say_hello(lua_State * L)
+{
+    lua_createtable(L, 0, 10);
+    lua_pushstring(L, "helloword!");
+    return 1;
+}
+
+static int
+ngx_http_lua_upstream_add_server(lua_State * L)
+{
+    ngx_str_t host, id;
+    ngx_http_upstream_server_t *us;
+    ngx_http_upstream_srv_conf_t *uscf;
+    ngx_url_t u;
+    ngx_http_request_t *r;
+    ngx_int_t weight, max_fails;
+    time_t fail_timeout;
+
+    if (lua_gettop(L) != 5) {
+        // four param is :"upstream name", "ip:port" , "weight" , "max_fails", 
+        //"fail_time"
+        // for lua code , you must pass this four param, is none ,you should 
+        // consider pass default value.
+        return luaL_error(L, "exactly five argument expected");
+    }
+
+    r = ngx_http_lua_get_request(L);
+    if (r == NULL) {
+        lua_pushnil(L);
+        lua_pushliteral(L, "get request error \n");
+        return 2;
+    }
+
+    host.data = (u_char *) luaL_checklstring(L, 1, &host.len);
+
+    ngx_memzero(&u, sizeof (ngx_url_t));
+    u.url.data = (u_char *) luaL_checklstring(L, 2, &u.url.len);
+    u.default_port = 80;
+
+    weight = (ngx_int_t) luaL_checkint(L, 3);
+    max_fails = (ngx_int_t) luaL_checkint(L, 4);
+    fail_timeout = (time_t) luaL_checklong(L, 5);
+#if (NGX_DEBUG)
+    ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0, "%s %s params: %s,%s,%d,%d,%d\n", __FILE__,__FUNCTION__, host.data, u.url.data, weight, max_fails, fail_timeout);
+#endif
+    uscf = ngx_http_lua_upstream_find_upstream(L, &host);
+    if (uscf == NULL) {
+        lua_pushnil(L);
+        lua_pushliteral(L, "upstream not found\n");
+        return 2;
+    }
+
+
+    if (uscf->servers == NULL || uscf->servers->nelts == 0) {
+        //TODO: 对于 默认的空upstream来讲，nginx当前会不允许其启动，可以考虑调整策略，允许此种情况下nginx启动
+        //
+        lua_pushliteral(L, "upstream has no server before!\n");
+        lua_newtable(L);
+        return 2;
+    } else {
+        if (ngx_parse_url(uscf->servers->pool, &u) != NGX_OK) {
+            if (u.err) {
+                lua_pushnil(L);
+                lua_pushliteral(L, "url parser error");
+                return 2;
+            }
+        }
+
+        us = ngx_array_push(uscf->servers);
+        if (us == NULL) {
+            lua_pushliteral(L, "us push uscf->servers failed\n");
+            return 3;
+        }
+        ngx_memzero(us, sizeof (ngx_http_upstream_server_t));
+        us->host = u.host;
+        ngx_str_null(&id);
+        us->id = id;
+        us->addrs = u.addrs;
+        us->naddrs = u.naddrs;
+        us->weight = weight;
+        us->max_fails = max_fails;
+        us->fail_timeout = fail_timeout;
+
+    }
+
+    return 1;
+}
 
 static int
 ngx_http_lua_upstream_get_upstreams(lua_State * L)
 {
-    ngx_uint_t                            i;
-    ngx_http_upstream_srv_conf_t        **uscfp, *uscf;
-    ngx_http_upstream_main_conf_t        *umcf;
+    ngx_uint_t i;
+    ngx_http_upstream_srv_conf_t **uscfp, *uscf;
+    ngx_http_upstream_main_conf_t *umcf;
 
     if (lua_gettop(L) != 0) {
         return luaL_error(L, "no argument expected");
@@ -137,14 +235,13 @@ ngx_http_lua_upstream_get_upstreams(lua_State * L)
     return 1;
 }
 
-
 static int
 ngx_http_lua_upstream_get_servers(lua_State * L)
 {
-    ngx_str_t                             host;
-    ngx_uint_t                            i, j, n;
-    ngx_http_upstream_server_t           *server;
-    ngx_http_upstream_srv_conf_t         *us;
+    ngx_str_t host;
+    ngx_uint_t i, j, n;
+    ngx_http_upstream_server_t *server;
+    ngx_http_upstream_srv_conf_t *us;
 
     if (lua_gettop(L) != 1) {
         return luaL_error(L, "exactly one argument expected");
@@ -186,14 +283,14 @@ ngx_http_lua_upstream_get_servers(lua_State * L)
 
         if (server[i].naddrs == 1) {
             lua_pushlstring(L, (char *) server[i].addrs->name.data,
-                            server[i].addrs->name.len);
+                    server[i].addrs->name.len);
 
         } else {
             lua_createtable(L, server[i].naddrs, 0);
 
             for (j = 0; j < server[i].naddrs; j++) {
                 lua_pushlstring(L, (char *) server[i].addrs[j].name.data,
-                                server[i].addrs[j].name.len);
+                        server[i].addrs[j].name.len);
                 lua_rawseti(L, -2, j + 1);
             }
         }
@@ -230,14 +327,13 @@ ngx_http_lua_upstream_get_servers(lua_State * L)
     return 1;
 }
 
-
 static int
 ngx_http_lua_upstream_get_primary_peers(lua_State * L)
 {
-    ngx_str_t                             host;
-    ngx_uint_t                            i;
-    ngx_http_upstream_rr_peers_t         *peers;
-    ngx_http_upstream_srv_conf_t         *us;
+    ngx_str_t host;
+    ngx_uint_t i;
+    ngx_http_upstream_rr_peers_t *peers;
+    ngx_http_upstream_srv_conf_t *us;
 
     if (lua_gettop(L) != 1) {
         return luaL_error(L, "exactly one argument expected");
@@ -270,14 +366,13 @@ ngx_http_lua_upstream_get_primary_peers(lua_State * L)
     return 1;
 }
 
-
 static int
 ngx_http_lua_upstream_get_backup_peers(lua_State * L)
 {
-    ngx_str_t                             host;
-    ngx_uint_t                            i;
-    ngx_http_upstream_rr_peers_t         *peers;
-    ngx_http_upstream_srv_conf_t         *us;
+    ngx_str_t host;
+    ngx_uint_t i;
+    ngx_http_upstream_rr_peers_t *peers;
+    ngx_http_upstream_srv_conf_t *us;
 
     if (lua_gettop(L) != 1) {
         return luaL_error(L, "exactly one argument expected");
@@ -316,11 +411,10 @@ ngx_http_lua_upstream_get_backup_peers(lua_State * L)
     return 1;
 }
 
-
 static int
 ngx_http_lua_upstream_set_peer_down(lua_State * L)
 {
-    ngx_http_upstream_rr_peer_t          *peer;
+    ngx_http_upstream_rr_peer_t *peer;
 
     if (lua_gettop(L) != 4) {
         return luaL_error(L, "exactly 4 arguments expected");
@@ -337,14 +431,13 @@ ngx_http_lua_upstream_set_peer_down(lua_State * L)
     return 1;
 }
 
-
 static ngx_http_upstream_rr_peer_t *
 ngx_http_lua_upstream_lookup_peer(lua_State *L)
 {
-    int                                   id, backup;
-    ngx_str_t                             host;
-    ngx_http_upstream_srv_conf_t         *us;
-    ngx_http_upstream_rr_peers_t         *peers;
+    int id, backup;
+    ngx_str_t host;
+    ngx_http_upstream_srv_conf_t *us;
+    ngx_http_upstream_rr_peers_t *peers;
 
     host.data = (u_char *) luaL_checklstring(L, 1, &host.len);
 
@@ -384,12 +477,11 @@ ngx_http_lua_upstream_lookup_peer(lua_State *L)
     return &peers->peer[id];
 }
 
-
 static int
 ngx_http_lua_get_peer(lua_State *L, ngx_http_upstream_rr_peer_t *peer,
-    ngx_uint_t id)
+                      ngx_uint_t id)
 {
-    ngx_uint_t     n;
+    ngx_uint_t n;
 
     n = 8;
 
@@ -460,32 +552,30 @@ ngx_http_lua_get_peer(lua_State *L, ngx_http_upstream_rr_peer_t *peer,
     return 0;
 }
 
-
 static ngx_http_upstream_main_conf_t *
 ngx_http_lua_upstream_get_upstream_main_conf(lua_State *L)
 {
-    ngx_http_request_t                   *r;
+    ngx_http_request_t *r;
 
     r = ngx_http_lua_get_request(L);
 
     if (r == NULL) {
         return ngx_http_cycle_get_module_main_conf(ngx_cycle,
-                                                   ngx_http_upstream_module);
+                ngx_http_upstream_module);
     }
 
     return ngx_http_get_module_main_conf(r, ngx_http_upstream_module);
 }
 
-
 static ngx_http_upstream_srv_conf_t *
 ngx_http_lua_upstream_find_upstream(lua_State *L, ngx_str_t *host)
 {
-    u_char                               *port;
-    size_t                                len;
-    ngx_int_t                             n;
-    ngx_uint_t                            i;
-    ngx_http_upstream_srv_conf_t        **uscfp, *uscf;
-    ngx_http_upstream_main_conf_t        *umcf;
+    u_char *port;
+    size_t len;
+    ngx_int_t n;
+    ngx_uint_t i;
+    ngx_http_upstream_srv_conf_t **uscfp, *uscf;
+    ngx_http_upstream_main_conf_t *umcf;
 
     umcf = ngx_http_lua_upstream_get_upstream_main_conf(L);
     uscfp = umcf->upstreams.elts;
@@ -495,8 +585,7 @@ ngx_http_lua_upstream_find_upstream(lua_State *L, ngx_str_t *host)
         uscf = uscfp[i];
 
         if (uscf->host.len == host->len
-            && ngx_memcmp(uscf->host.data, host->data, host->len) == 0)
-        {
+                && ngx_memcmp(uscf->host.data, host->data, host->len) == 0) {
             return uscf;
         }
     }
@@ -518,10 +607,9 @@ ngx_http_lua_upstream_find_upstream(lua_State *L, ngx_str_t *host)
             uscf = uscfp[i];
 
             if (uscf->port
-                && uscf->port == n
-                && uscf->host.len == len
-                && ngx_memcmp(uscf->host.data, host->data, len) == 0)
-            {
+                    && uscf->port == n
+                    && uscf->host.len == len
+                    && ngx_memcmp(uscf->host.data, host->data, len) == 0) {
                 return uscf;
             }
         }
@@ -529,3 +617,4 @@ ngx_http_lua_upstream_find_upstream(lua_State *L, ngx_str_t *host)
 
     return NULL;
 }
+
diff --git a/t/sanity.t b/t/sanity.t
index dd17159..95748eb 100644
--- a/t/sanity.t
+++ b/t/sanity.t
@@ -564,3 +564,73 @@ upstream 127.0.0.1:1130:
 --- no_error_log
 [error]
 
+=== TEST 15: add server with upstream
+--- http_config
+     upstream foo.com {
+        server 127.0.0.1 fail_timeout=53 weight=4 max_fails=100;
+        server agentzh.org:81;
+    }
+
+    upstream bar {
+        server 127.0.0.2;
+    }
+--- config
+
+    location  /add_server {
+
+                default_type text/plain;
+                content_by_lua '
+
+                        local concat = table.concat
+                        local upstream = require "ngx.upstream"
+                        local get_servers = upstream.get_servers
+                        local get_upstreams = upstream.get_upstreams
+                        local add_server = upstream.add_server
+
+                        local args =  ngx.req.get_uri_args()
+                        local upstream_name
+
+                        upstream_name = args["upstream"]
+                        local server_ip = args["ip"]
+                        local server_port = args["port"]
+                        local weight = 1
+                        local max_fails = 10
+                        local fail_timeout = 10
+
+
+                        local err = add_server("bar",server_ip..":"..server_port,weight,max_fails,fail_timeout)
+
+                        local srvs, err = get_servers(upstream_name)
+                        if not srvs then
+                                ngx.say("failed to get servers in upstream ", upstream_name)
+                        else
+                                for _, srv in ipairs(srvs) do
+                                        local first = true
+                                        for k, v in pairs(srv) do
+                                                if first then
+                                                        first = false
+                                                        ngx.print("    ")
+                                                else
+                                                        ngx.print(", ")
+                                                end
+                                                if type(v) == "table" then
+                                                        ngx.print(k, " = {", concat(v, ", "), "}")
+                                                else
+                                                        ngx.print(k, " = ", v)
+                                                end
+                                        end
+                                        ngx.print("\\n")
+                                end
+                        end
+
+
+                ';
+        }
+--- request
+    GET /add_server?upstream=bar&ip=127.0.0.9&port=12855
+--- response_body
+    fail_timeout = 10, addr = 127.0.0.2:80, max_fails = 1, weight = 1
+    fail_timeout = 10, addr = 127.0.0.9:12855, max_fails = 10, weight = 1
+
+--- no_error_log
+[error]
\ No newline at end of file