docs(serializer): trim endpoint filter list comments to match neighboring settings

Author: jhoenzsch

pkg/config/schema/yaml/core_schema.yaml

@@ -8522,21 +8522,15 @@ properties:
         type: string
       type: array
     comment: |-
-      Per-endpoint metric filter lists, keyed by the endpoint URL exactly as it is
-      configured under `dd_url` or `additional_endpoints`. Metrics named in an entry are
-      not sent to that endpoint, and every other endpoint keeps receiving them.
+      Keyed by the endpoint URL exactly as configured under `dd_url` or
+      `additional_endpoints`. Unlike metric_filterlist, which drops during sampling and
+      so affects every destination, this is applied per destination as its payload is
+      built.
 
-      This differs from `metric_filterlist`, which is applied while metrics are sampled
-      and therefore removes them from every destination. This setting is applied when the
-      payload for each destination is built, so it can single out one endpoint.
-
-      Names are matched exactly. metric_filterlist_match_prefix does not apply, because
-      Remote Config resets that setting whenever it pushes a metric filter list.
-
-      Requires use_v2_api.series, which is the default. On the v1 series API a single
-      payload is built and copied to every destination, so there is no point at which a
-      per-endpoint filter can be applied; the Agent logs a warning if both are set.
-      Sketches are unaffected and always honour these lists.
+      Names are matched exactly; metric_filterlist_match_prefix does not apply, because
+      Remote Config resets that setting whenever it pushes a filter list. Requires
+      use_v2_api.series (the default): the v1 path builds one payload for all
+      destinations, so nothing can be filtered per endpoint there.
     tags:
     - full-agent-only:true
   metric_filterlist_match_prefix:

pkg/serializer/metrics.go

@@ -238,8 +238,7 @@ func (s *Serializer) buildPipelinesRng(kind metricsKind, rng prng) metrics.Pipel
 				dest.ValidationBatchID = s.genUUID()
 			}
 
-			// An endpoint with its own filter list only receives the metrics
-			// that list does not name. Every other endpoint is unaffected.
+			// Endpoints without a filter list receive every metric.
 			var filter metrics.Filter = metrics.AllowAllFilter{}
 			if endpointFilter, ok := endpointFilters[resolver.GetConfigName()]; ok {
 				filter = endpointFilter

pkg/serializer/metrics_test.go

@@ -334,16 +334,15 @@ func TestEndpointFilterListsIgnoredOnV1Series(t *testing.T) {
 	compressor := metricscompressionimpl.NewComponent(metricscompressionimpl.Requires{Cfg: config}).Comp
 	s := NewSerializer(f, nil, compressor, config, logger, "")
 
-	// The warning is emitted once and must not panic or alter the pipelines that
-	// other payload kinds still build.
+	// Emitted once; sketches must still honor the list.
 	s.warnEndpointFilterListsIgnored()
 	s.warnEndpointFilterListsIgnored()
 
 	pipelines := s.buildPipelines(metricsKindSketches)
 	require.Len(t, pipelines, 1)
 	for conf := range pipelines {
 		assert.False(t, conf.Filter.Filter(filterableMetric("datadog.agent.running")),
-			"sketches still honour the endpoint filter list")
+			"sketches still honor the endpoint filter list")
 	}
 }