Create get_endpoint_string and refactor

Author: gulachek

rootfs/etc/nginx/lua/test/balancer/sticky_test.lua

@@ -73,7 +73,7 @@ describe("Sticky", function()
   end)
 
   local test_backend = get_test_backend()
-  local test_backend_endpoint= test_backend.endpoints[1].address .. ":" .. test_backend.endpoints[1].port
+  local test_backend_endpoint= util.get_endpoint_string(test_backend.endpoints[1])
 
   local legacy_cookie_value = test_backend_endpoint
   local function create_current_cookie_value(backend_key)

rootfs/etc/nginx/lua/util.lua

@@ -13,12 +13,16 @@ local re_gmatch     = ngx.re.gmatch
 
 local _M = {}
 
+function _M.get_endpoint_string(endpoint)
+	return endpoint.address .. ":" .. endpoint.port
+end
+
 function _M.get_nodes(endpoints)
   local nodes = {}
   local weight = 1
 
   for _, endpoint in pairs(endpoints) do
-    local endpoint_string = endpoint.address .. ":" .. endpoint.port
+    local endpoint_string = _M.get_endpoint_string(endpoint)
     nodes[endpoint_string] = weight
   end