Don't generate a config when disabling logs collection with hints (el…

…astic#9305)

When `co.elastic.logs/disable="true"` is used in a container, an
incomplete event is generated, what provokes errors about configurations
with missing fields. Don't generate configs in these cases.

If after that a builder doesn't generate any configuration,
it still generates an event but with with an empty list of configs
instead of an event without a config field.

(cherry picked from commit a4b06ae)

CHANGELOG.asciidoc

@@ -39,6 +39,9 @@ https://github.com/elastic/beats/compare/v6.5.1...6.5[Check the HEAD diff]
 
 *Filebeat*
 
+- Don't generate incomplete configurations when logs collection is disabled by hints. {pull}9305[9305]
+- Stop runners disabled by hints after previously being started. {pull}9305[9305]
+
 *Heartbeat*
 
 *Journalbeat*

filebeat/autodiscover/builder/hints/logs.go

@@ -84,8 +84,9 @@ func (l *logHints) CreateConfig(event bus.Event) []*common.Config {
 		hints, _ = hIface.(common.MapStr)
 	}
 
-	if builder.IsNoOp(hints, l.Key) == true {
-		return []*common.Config{config}
+	if builder.IsNoOp(hints, l.Key) {
+		logp.Debug("hints.builder", "disabled config in event: %+v", event)
+		return []*common.Config{}
 	}
 
 	inputConfig := l.getInputs(hints)

libbeat/autodiscover/builder.go

@@ -89,7 +89,7 @@ func (r *registry) BuildBuilder(c *common.Config) (Builder, error) {
 
 // GetConfig creates configs for all builders initialized.
 func (b Builders) GetConfig(event bus.Event) []*common.Config {
-	var configs []*common.Config
+	configs := []*common.Config{}
 
 	for _, builder := range b {
 		if config := builder.CreateConfig(event); config != nil {

libbeat/autodiscover/providers/kubernetes/kubernetes_test.go

@@ -224,6 +224,7 @@ func TestEmitEvent(t *testing.T) {
 						},
 					},
 				},
+				"config": []*common.Config{},
 			},
 		},
 		{
@@ -282,7 +283,7 @@ func TestEmitEvent(t *testing.T) {
 
 		select {
 		case event := <-listener.Events():
-			assert.Equal(t, test.Expected, event)
+			assert.Equal(t, test.Expected, event, test.Message)
 		case <-time.After(2 * time.Second):
 			if test.Expected != nil {
 				t.Fatal("Timeout while waiting for event")