Configure DataDog host and port from env variables

kong/plugins/datadog/schema.lua

@@ -73,8 +73,9 @@ return {
         type = "record",
         default = { metrics = DEFAULT_METRICS },
         fields = {
-          { host = typedefs.host({ required = true, default = "localhost" }), },
-          { port = typedefs.port({ required = true, default = 8125 }), },
+          { use_env = { type = "boolean", default = false } },
+          { host = typedefs.host({ default = "localhost" }), },
+          { port = typedefs.port({ default = 8125 }), },
           { prefix = { type = "string", default = "kong" }, },
           { metrics = {
               type     = "array",
@@ -95,7 +96,17 @@ return {
                     if_match = { one_of = { "counter", "gauge" }, },
                     then_field = "sample_rate",
                     then_match = { required = true },
-                  }, },
-  }, }, }, }, }, }, }, },
+          }, }, }, }, }, },
+        },
+        entity_checks = {
+          { conditional = {
+            if_field = "use_env", if_match = {eq = false},
+            then_field = "host", then_match = { required = true },
+          }, },
+          { conditional = {
+            if_field = "use_env", if_match = {eq = false},
+            then_field = "port", then_match = { required = true },
+          }, },
+  }, }, }, },
 }
 

kong/plugins/datadog/statsd_logger.lua

@@ -19,18 +19,33 @@ local stat_types = {
 local statsd_mt = {}
 statsd_mt.__index = statsd_mt
 
+local env_datadog_agent_host = os.getenv 'KONG_DATADOG_AGENT_HOST'
+local env_datadog_agent_port = tonumber(os.getenv 'KONG_DATADOG_AGENT_PORT' or "")
 
 function statsd_mt:new(conf)
   local sock   = udp()
-  local _, err = sock:setpeername(conf.host, conf.port)
+
+  local host, port
+  if conf.use_env then
+    if not (env_datadog_agent_host and env_datadog_agent_port) then
+      return nil, "both KONG_DATADOG_AGENT_HOST and KONG_DATADOG_AGENT_PORT must be set"
+    end
+    host = env_datadog_agent_host
+    port = env_datadog_agent_port
+  else
+    host = conf.host
+    port = conf.port
+  end
+
+  local _, err = sock:setpeername(host, port)
   if err then
-    return nil, fmt("failed to connect to %s:%s: %s", conf.host,
-                    tostring(conf.port), err)
+    return nil, fmt("failed to connect to %s:%s: %s", host,
+                    tostring(port), err)
   end
 
   local statsd = {
-    host       = conf.host,
-    port       = conf.port,
+    host       = host,
+    port       = port,
     prefix     = conf.prefix,
     socket     = sock,
     stat_types = stat_types,

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

@@ -45,6 +45,11 @@ for _, strategy in helpers.each_strategy() do
         service = bp.services:insert { name = "dd4" }
       }
 
+      local route5 = bp.routes:insert {
+        hosts   = { "datadog5.com" },
+        service = bp.services:insert { name = "dd5" }
+      }
+
       local route_grpc = assert(bp.routes:insert {
         protocols = { "grpc" },
         paths = { "/hello.HelloService/" },
@@ -122,6 +127,21 @@ for _, strategy in helpers.each_strategy() do
         },
       }
 
+      bp.plugins:insert {
+        name     = "key-auth",
+        route = { id = route5.id },
+      }
+
+      helpers.setenv('KONG_DATADOG_AGENT_HOST', 'localhost')
+      helpers.setenv('KONG_DATADOG_AGENT_PORT', '9999')
+      bp.plugins:insert {
+        name     = "datadog",
+        route = { id = route5.id },
+        config   = {
+          use_env = true,
+        },
+      }
+
       bp.plugins:insert {
         name       = "key-auth",
         route = { id = route_grpc.id },
@@ -148,6 +168,9 @@ for _, strategy in helpers.each_strategy() do
         proxy_client:close()
       end
 
+      helpers.unsetenv('KONG_DATADOG_AGENT_HOST')
+      helpers.unsetenv('KONG_DATADOG_AGENT_PORT')
+
       helpers.stop_kong()
     end)
 
@@ -257,6 +280,29 @@ for _, strategy in helpers.each_strategy() do
       assert.contains("kong.latency:%d+|g|#name:dd3,status:200,T2:V2:V3,T4", gauges, true)
     end)
 
+    it("logs metrics to host/port defined via environment variables", function()
+      local thread = helpers.udp_server(9999, 6)
+
+      local res = assert(proxy_client:send {
+        method  = "GET",
+        path    = "/status/200?apikey=kong",
+        headers = {
+          ["Host"] = "datadog5.com"
+        }
+      })
+      assert.res_status(200, res)
+
+      local ok, gauges = thread:join()
+      assert.True(ok)
+      assert.equal(6, #gauges)
+      assert.contains("kong.request.count:1|c|#name:dd5,status:200,consumer:bar,app:kong" , gauges)
+      assert.contains("kong.latency:%d+|ms|#name:dd5,status:200,consumer:bar,app:kong", gauges, true)
+      assert.contains("kong.request.size:%d+|ms|#name:dd5,status:200,consumer:bar,app:kong", gauges, true)
+      assert.contains("kong.response.size:%d+|ms|#name:dd5,status:200,consumer:bar,app:kong", gauges, true)
+      assert.contains("kong.upstream_latency:%d+|ms|#name:dd5,status:200,consumer:bar,app:kong", gauges, true)
+      assert.contains("kong.kong_latency:%d*|ms|#name:dd5,status:200,consumer:bar,app:kong", gauges, true)
+    end)
+
     it("should not return a runtime error (regression)", function()
       local thread = helpers.udp_server(9999, 1, 1)
 

spec/03-plugins/08-datadog/02-schema_spec.lua

@@ -8,6 +8,19 @@ describe("Plugin: datadog (schema)", function()
     assert.is_nil(err)
     assert.is_truthy(ok)
   end)
+  it("rejects null host without use_env", function()
+    local _, err = v({ host = ngx.null, use_env = false }, schema_def)
+    assert.equal("required field missing", err.config.host)
+  end)
+  it("rejects null port without use_env", function()
+    local _, err = v({ port = ngx.null, use_env = false }, schema_def)
+    assert.equal("required field missing", err.config.port)
+  end)
+  it("accepts null host and port with use_env", function()
+    local ok, err = v({ host = ngx.null, port = ngx.null, use_env = true }, schema_def)
+    assert.is_nil(err)
+    assert.is_truthy(ok)
+  end)
   it("accepts empty metrics", function()
     local metrics_input = {}
     local ok, err = v({ metrics = metrics_input }, schema_def)