fix(plugins/datadog): add return value for log function in batch queue

CHANGELOG.md

@@ -103,6 +103,8 @@
   [#9877](https://github.com/Kong/kong/pull/9877)
 - **JWT**: Deny requests that have different tokens in the jwt token search locations. Thanks Jackson 'Che-Chun' Kuo from Latacora for reporting this issue.
   [#9946](https://github.com/Kong/kong/pull/9946)
+- **Datadog**: Fix a bug in the Datadog plugin batch queue processing where metrics are published multiple times.
+  [#10044](https://github.com/Kong/kong/pull/10044)
 
 #### Core
 

kong/plugins/datadog/handler.lua

@@ -57,7 +57,7 @@ local function log(conf, messages)
   local logger, err = statsd_logger:new(conf)
   if err then
     kong.log.err("failed to create Statsd logger: ", err)
-    return
+    return false, err
   end
 
   for _, message in ipairs(messages) do
@@ -103,6 +103,7 @@ local function log(conf, messages)
   end
 
   logger:close_socket()
+  return true
 end
 
 

spec/03-plugins/08-datadog/01-log_spec.lua

@@ -399,6 +399,25 @@ for _, strategy in helpers.each_strategy() do
       assert.contains("kong.kong_latency:%d*|ms|#name:dd7,status:200,consumer:bar,app:kong", gauges, true)
     end)
 
+    -- the purpose of this test case is to test the batch queue 
+    -- finish processing messages in one time(no retries)
+    it("no more messages than expected", function()
+      local thread = helpers.udp_server(9999, 10, 10)
+
+      local res = assert(proxy_client:send {
+        method  = "GET",
+        path    = "/status/200?apikey=kong",
+        headers = {
+          ["Host"] = "datadog7.com"
+        }
+      })
+      assert.res_status(200, res)
+
+      local ok, gauges = thread:join()
+      assert.True(ok)
+      assert.equal(6, #gauges)
+    end)
+
     it("should not return a runtime error (regression)", function()
       local thread = helpers.udp_server(9999, 1, 1)