[libbeat] Fix dropped queue feature metadata / remove unused helper (e…

…lastic#17666) (elastic#17756)

(cherry picked from commit a067c4a)

CHANGELOG-developer.next.asciidoc

@@ -35,6 +35,7 @@ The list below covers the major changes between 7.0.0-rc2 and master only.
 - Require logger as first parameter for `outputs.elasticsearch.client#BulkReadItemStatus`. {pull}16761[16761]
 - Extract Elasticsearch client logic from `outputs/elasticsearch` package into new `esclientleg` package. {pull}16150[16150]
 - Rename `queue.BufferConfig.Events` to `queue.BufferConfig.MaxEvents`. {pull}17622[17622]
+- Remove `queue.Feature` and replace `queue.RegisterType` with `queue.RegisterQueueType`. {pull}17666[17666]
 
 ==== Bugfixes
 

libbeat/publisher/queue/memqueue/broker.go

@@ -27,15 +27,6 @@ import (
 	"github.com/elastic/beats/v7/libbeat/publisher/queue"
 )
 
-// Feature exposes a memory queue.
-var Feature = queue.Feature("mem",
-	create,
-	feature.MakeDetails(
-		"Memory queue",
-		"Buffer events in memory before sending to the output.",
-		feature.Stable),
-)
-
 type broker struct {
 	done chan struct{}
 
@@ -81,7 +72,13 @@ type chanList struct {
 }
 
 func init() {
-	queue.RegisterType("mem", create)
+	queue.RegisterQueueType(
+		"mem",
+		create,
+		feature.MakeDetails(
+			"Memory queue",
+			"Buffer events in memory before sending to the output.",
+			feature.Stable))
 }
 
 func create(

libbeat/publisher/queue/queue_reg.go

@@ -22,12 +22,11 @@ import (
 )
 
 // Namespace is the feature namespace for queue definition.
-var Namespace = "libbeat.queue"
+const Namespace = "libbeat.queue"
 
-// RegisterType registers a new queue type.
-func RegisterType(name string, fn Factory) {
-	f := Feature(name, fn, feature.MakeDetails(name, "", feature.Undefined))
-	feature.MustRegister(f)
+// RegisterQueueType registers a new queue type.
+func RegisterQueueType(name string, factory Factory, details feature.Details) {
+	feature.MustRegister(feature.New(Namespace, name, factory, details))
 }
 
 // FindFactory retrieves a queue types constructor. Returns nil if queue type is unknown
@@ -43,8 +42,3 @@ func FindFactory(name string) Factory {
 
 	return factory
 }
-
-// Feature creates a new type of queue.
-func Feature(name string, factory Factory, description feature.Details) *feature.Feature {
-	return feature.New(Namespace, name, factory, description)
-}

libbeat/publisher/queue/spool/module.go

@@ -27,16 +27,14 @@ import (
 	"github.com/elastic/go-txfile"
 )
 
-// Feature exposes a spooling to disk queue.
-var Feature = queue.Feature("spool", create,
-	feature.MakeDetails(
-		"Memory queue",
-		"Buffer events in memory before sending to the output.",
-		feature.Beta),
-)
-
 func init() {
-	queue.RegisterType("spool", create)
+	queue.RegisterQueueType(
+		"spool",
+		create,
+		feature.MakeDetails(
+			"Disk spool",
+			"Buffer events in disk spool before sending to the output.",
+			feature.Beta))
 }
 
 func create(