Fixes bug where we tried to default config for the wrong components

.chloggen/add_all_receiver_defaults.yaml

@@ -13,4 +13,6 @@ issues: [3126]
 # (Optional) One or more lines of additional information to render under the primary note.
 # These lines will be padded with 2 spaces and then inserted directly into the document.
 # Use pipe (|) for multiline entries.
-subtext:
+subtext: |
+  This feature is enabled by default. It can be disabled by specifying
+  `--feature-gates=-operator.collector.default.config`.

apis/v1beta1/collector_webhook.go

@@ -30,6 +30,7 @@ import (
 	"github.com/open-telemetry/opentelemetry-operator/internal/fips"
 	ta "github.com/open-telemetry/opentelemetry-operator/internal/manifests/targetallocator/adapters"
 	"github.com/open-telemetry/opentelemetry-operator/internal/rbac"
+	"github.com/open-telemetry/opentelemetry-operator/pkg/featuregate"
 )
 
 var (
@@ -100,6 +101,9 @@ func (c CollectorWebhook) Default(_ context.Context, obj runtime.Object) error {
 	if len(otelcol.Spec.ManagementState) == 0 {
 		otelcol.Spec.ManagementState = ManagementStateManaged
 	}
+	if !featuregate.EnableConfigDefaulting.IsEnabled() {
+		return nil
+	}
 	return otelcol.Spec.Config.ApplyDefaults(c.logger)
 }
 

internal/components/generic_parser.go

@@ -44,15 +44,15 @@ func (g *GenericParser[T]) GetDefaultConfig(logger logr.Logger, config interface
 		return config, nil
 	}
 
-	if g.settings.defaultRecAddr == "" {
+	if g.settings.defaultRecAddr == "" || g.settings.port == 0 {
 		return config, nil
 	}
 
 	var parsed T
 	if err := mapstructure.Decode(config, &parsed); err != nil {
 		return nil, err
 	}
-	return g.defaultsApplier(logger, g.settings.defaultRecAddr, g.settings.GetServicePort().Port, parsed)
+	return g.defaultsApplier(logger, g.settings.defaultRecAddr, g.settings.port, parsed)
 }
 
 func (g *GenericParser[T]) GetLivenessProbe(logger logr.Logger, config interface{}) (*corev1.Probe, error) {

internal/components/receivers/single_endpoint_receiver_test.go

@@ -15,6 +15,7 @@
 package receivers_test
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -82,6 +83,7 @@ func TestDownstreamParsers(t *testing.T) {
 		{"awsxray", "awsxray", "__awsxray", 2000, false},
 		{"tcplog", "tcplog", "__tcplog", 0, true},
 		{"udplog", "udplog", "__udplog", 0, true},
+		{"k8s_cluster", "k8s_cluster", "__k8s_cluster", 0, false},
 	} {
 		t.Run(tt.receiverName, func(t *testing.T) {
 			t.Run("builds successfully", func(t *testing.T) {
@@ -143,6 +145,28 @@ func TestDownstreamParsers(t *testing.T) {
 				assert.EqualValues(t, 65535, ports[0].Port)
 				assert.Equal(t, naming.PortName(tt.receiverName, int32(tt.defaultPort)), ports[0].Name)
 			})
+
+			t.Run("returns a default config", func(t *testing.T) {
+				// prepare
+				parser := receivers.ReceiverFor(tt.receiverName)
+
+				// test
+				config, err := parser.GetDefaultConfig(logger, map[string]interface{}{})
+
+				// verify
+				assert.NoError(t, err)
+				configMap, ok := config.(map[string]interface{})
+				assert.True(t, ok)
+				if tt.defaultPort == 0 {
+					assert.Empty(t, configMap, 0)
+					return
+				}
+				if tt.listenAddrParser {
+					assert.Equal(t, configMap["listen_address"], fmt.Sprintf("0.0.0.0:%d", tt.defaultPort))
+				} else {
+					assert.Equal(t, configMap["endpoint"], fmt.Sprintf("0.0.0.0:%d", tt.defaultPort))
+				}
+			})
 		})
 	}
 }

pkg/featuregate/featuregate.go

@@ -40,6 +40,13 @@ var (
 		featuregate.WithRegisterDescription("enables feature to set GOMEMLIMIT and GOMAXPROCS automatically"),
 		featuregate.WithRegisterFromVersion("v0.100.0"),
 	)
+	// EnableConfigDefaulting is the feature gate that enables the operator to default the endpoint for known components.
+	EnableConfigDefaulting = featuregate.GlobalRegistry().MustRegister(
+		"operator.collector.default.config",
+		featuregate.StageBeta,
+		featuregate.WithRegisterDescription("enables the operator to default the endpoint for known components"),
+		featuregate.WithRegisterFromVersion("v0.110.0"),
+	)
 )
 
 // Flags creates a new FlagSet that represents the available featuregate flags using the supplied featuregate registry.