add batch processor deprecation warning

.chloggen/batch-processor-deprecation-warning.yaml

@@ -0,0 +1,20 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: deprecation
+
+# The name of the component, or a single word describing the area of concern, (e.g. collector, target allocator, auto-instrumentation, opamp, github action)
+component: collector
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add deprecation warning for OpenTelemetryCollector resources using the batch processor
+
+# One or more tracking issues related to the change
+issues: [4648]
+
+# (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: |
+  The batch processor is being deprecated in the OpenTelemetry Collector project.
+  A warning event is now emitted when an OpenTelemetryCollector CR uses the batch processor,
+  directing users to migrate to alternative batching solutions.
+  See https://github.com/open-telemetry/opentelemetry-collector/issues/12022 for more details.

apis/v1beta1/config.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"math"
 	"sort"
+	"strings"
 
 	"dario.cat/mergo"
 	"github.com/go-logr/logr"
@@ -355,7 +356,31 @@ func (c *Config) GetAllRbacRules(logger logr.Logger) ([]rbacv1.PolicyRule, error
 }
 
 func (c *Config) ApplyDefaults(logger logr.Logger) ([]EventInfo, error) {
-	return c.applyDefaultForComponentKinds(logger, KindReceiver, KindExtension)
+	events, err := c.applyDefaultForComponentKinds(logger, KindReceiver, KindExtension)
+	if err != nil {
+		return events, err
+	}
+
+	// Check for deprecated batch processor
+	enabledComponents := c.GetEnabledComponents()
+	for processorName := range enabledComponents[KindProcessor] {
+		if processorName == "batch" || strings.HasPrefix(processorName, "batch/") {
+			const issueID = "https://github.com/open-telemetry/opentelemetry-collector/issues/12022"
+			warnStr := fmt.Sprintf(
+				"The batch processor is deprecated and will be removed in a future release. "+
+					"Please consider migrating to alternative batching solutions. See: %s",
+				issueID,
+			)
+			events = append(events, EventInfo{
+				Type:    corev1.EventTypeWarning,
+				Reason:  "BatchProcessorDeprecated",
+				Message: warnStr,
+			})
+			break
+		}
+	}
+
+	return events, nil
 }
 
 // GetLivenessProbe gets the first enabled liveness probe. There should only ever be one extension enabled

apis/v1beta1/config_test.go

@@ -1482,3 +1482,150 @@ func TestTelemetryIncompleteConfigAppliesDefaults(t *testing.T) {
 	require.Equal(t, "0.0.0.0", *telemetry.Metrics.Readers[0].Pull.Exporter.Prometheus.Host)
 	require.Equal(t, 8888, *telemetry.Metrics.Readers[0].Pull.Exporter.Prometheus.Port)
 }
+
+func TestBatchProcessorDeprecationWarning(t *testing.T) {
+	tests := []struct {
+		name          string
+		config        *Config
+		wantWarning   bool
+		wantEventType string
+	}{
+		{
+			name: "batch processor enabled should emit deprecation warning",
+			config: &Config{
+				Receivers: AnyConfig{
+					Object: map[string]interface{}{
+						"otlp": map[string]interface{}{},
+					},
+				},
+				Exporters: AnyConfig{
+					Object: map[string]interface{}{
+						"otlp": map[string]interface{}{},
+					},
+				},
+				Processors: &AnyConfig{
+					Object: map[string]interface{}{
+						"batch": map[string]interface{}{},
+					},
+				},
+				Service: Service{
+					Pipelines: map[string]*Pipeline{
+						"traces": {
+							Receivers:  []string{"otlp"},
+							Processors: []string{"batch"},
+							Exporters:  []string{"otlp"},
+						},
+					},
+				},
+			},
+			wantWarning:   true,
+			wantEventType: v1.EventTypeWarning,
+		},
+		{
+			name: "batch processor with instance name should emit deprecation warning",
+			config: &Config{
+				Receivers: AnyConfig{
+					Object: map[string]interface{}{
+						"otlp": map[string]interface{}{},
+					},
+				},
+				Exporters: AnyConfig{
+					Object: map[string]interface{}{
+						"otlp": map[string]interface{}{},
+					},
+				},
+				Processors: &AnyConfig{
+					Object: map[string]interface{}{
+						"batch/custom": map[string]interface{}{},
+					},
+				},
+				Service: Service{
+					Pipelines: map[string]*Pipeline{
+						"traces": {
+							Receivers:  []string{"otlp"},
+							Processors: []string{"batch/custom"},
+							Exporters:  []string{"otlp"},
+						},
+					},
+				},
+			},
+			wantWarning:   true,
+			wantEventType: v1.EventTypeWarning,
+		},
+		{
+			name: "no batch processor should not emit warning",
+			config: &Config{
+				Receivers: AnyConfig{
+					Object: map[string]interface{}{
+						"otlp": map[string]interface{}{},
+					},
+				},
+				Exporters: AnyConfig{
+					Object: map[string]interface{}{
+						"otlp": map[string]interface{}{},
+					},
+				},
+				Processors: &AnyConfig{
+					Object: map[string]interface{}{
+						"memory_limiter": map[string]interface{}{},
+					},
+				},
+				Service: Service{
+					Pipelines: map[string]*Pipeline{
+						"traces": {
+							Receivers:  []string{"otlp"},
+							Processors: []string{"memory_limiter"},
+							Exporters:  []string{"otlp"},
+						},
+					},
+				},
+			},
+			wantWarning: false,
+		},
+		{
+			name: "nil processors should not emit warning",
+			config: &Config{
+				Receivers: AnyConfig{
+					Object: map[string]interface{}{
+						"otlp": map[string]interface{}{},
+					},
+				},
+				Exporters: AnyConfig{
+					Object: map[string]interface{}{
+						"otlp": map[string]interface{}{},
+					},
+				},
+				Processors: nil,
+				Service: Service{
+					Pipelines: map[string]*Pipeline{
+						"traces": {
+							Receivers: []string{"otlp"},
+							Exporters: []string{"otlp"},
+						},
+					},
+				},
+			},
+			wantWarning: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			events, err := tt.config.ApplyDefaults(logr.Discard())
+			require.NoError(t, err)
+
+			var foundWarning bool
+			for _, event := range events {
+				if event.Reason == "BatchProcessorDeprecated" {
+					foundWarning = true
+					assert.Equal(t, tt.wantEventType, event.Type)
+					assert.Contains(t, event.Message, "batch processor is deprecated")
+					assert.Contains(t, event.Message, "https://github.com/open-telemetry/opentelemetry-collector/issues/12022")
+					break
+				}
+			}
+
+			assert.Equal(t, tt.wantWarning, foundWarning, "batch processor deprecation warning presence mismatch")
+		})
+	}
+}