feat(collector/receiver): support extra fields in structured JSON function logs

collector/receiver/telemetryapireceiver/README.md

@@ -13,6 +13,20 @@ Supported events:
 * `platform.initStart` - The receiver uses this event to record the start time of the function initialization period. Once both start and end times are recorded, the receiver generates a span named `platform.initRuntimeDone` to record the event.
 * `platform.initRuntimeDone` - The receiver uses this event to record the end time of the function initialization period. Once both start and end times are recorded, the receiver generates a span named `platform.initRuntimeDone` to record the event.
 
+## Logs metadata reserved fields
+
+The following field names are reserved for internal use in logs metadata and must not be used as custom metadata keys:
+
+| Field       | Description                              |
+|-------------|------------------------------------------|
+| `level`     | Log severity level                       |
+| `message`   | Log message body                         |
+| `requestId` | AWS Lambda request identifier            |
+| `timestamp` | Time of the log event                    |
+| `type`      | Telemetry API event type                 |
+
+> **Note:** These fields are populated internally by the receiver and will take priority over any user-provided metadata with the same name. You should be aware of these limitations and handle conflicts at the business logic level — for example, by renaming custom fields that collide with reserved names before they are emitted as log metadata.
+
 ## Configuration
 
 | Field                 | Default                               | Description                                                                                                                                                          |

collector/receiver/telemetryapireceiver/receiver.go

@@ -490,6 +490,20 @@ func (r *telemetryAPIReceiver) createLogs(slice []event) (plog.Logs, error) {
 				}
 			} else if line, ok := record["message"].(string); ok {
 				logRecord.Body().SetStr(line)
+
+				for key, value := range record {
+					switch key {
+					case "level", "message", "requestId", "timestamp", "type":
+						continue
+					default:
+						attr, _ := logRecord.Attributes().GetOrPutEmpty(key)
+						if err := attr.FromRaw(value); err != nil {
+							logRecord.Attributes().Remove(key)
+							r.logger.Warn("Failed while converting field to attribute", zap.String("key", key), zap.Error(err))
+							continue
+						}
+					}
+				}
 			}
 		} else {
 			if requestId := r.getCurrentRequestId(); requestId != "" {

collector/receiver/telemetryapireceiver/receiver_test.go

@@ -359,6 +359,7 @@ func TestCreateLogs(t *testing.T) {
 		containsRequestId bool
 		requestId         string
 		severityNumber    plog.SeverityNumber
+		attributes        map[string]interface{}
 	}
 
 	testCases := []struct {
@@ -479,6 +480,137 @@ func TestCreateLogs(t *testing.T) {
 			},
 			expectError: false,
 		},
+		{
+			desc: "function json with extra fields",
+			slice: []event{
+				{
+					Time: "2026-02-26T20:15:32.000Z",
+					Type: "function",
+					Record: map[string]any{
+						"timestamp":              "2026-02-26T20:15:32.000Z",
+						"level":                  "INFO",
+						"requestId":              "79b4f56e-95b1-4643-9700-2807f4e6",
+						"message":                "Hello world, I am a function with extra data!",
+						"extraString":            "stringValue",
+						"extraNumber":            float64(2217),
+						"extraFloat":             3.14,
+						"extraBoolean":           true,
+						"extraNull":              nil,
+						"extraArrayOfStrings":    []any{"stringValue", "stringValue"},
+						"extraArrayOfNumbers":    []any{float64(2217), float64(2217)},
+						"extraArrayOfMixedTypes": []any{"stringValue", float64(2217), true, nil},
+						"extraArrayWithNesting":  []any{"stringValue", []any{float64(2217), []any{true, nil}}},
+						"extraObject": map[string]any{
+							"stringValue":  "stringValue",
+							"numberValue":  float64(2217),
+							"booleanValue": true,
+							"nullValue":    nil,
+						},
+						"extraObjectWithNesting": map[string]any{
+							"stringValue":  "stringValue",
+							"numberValue":  float64(2217),
+							"booleanValue": true,
+							"nullValue":    nil,
+							"arrayValue":   []any{"stringValue", float64(2217)},
+							"objectValue": map[string]any{
+								"stringValue": "stringValue",
+								"numberValue": float64(2217),
+							},
+						},
+					},
+				},
+			},
+			expectedLogs: []logInfo{
+				{
+					logType:           "function",
+					timestamp:         "2026-02-26T20:15:32.000Z",
+					body:              "Hello world, I am a function with extra data!",
+					containsRequestId: true,
+					requestId:         "79b4f56e-95b1-4643-9700-2807f4e6",
+					severityText:      "Info",
+					severityNumber:    plog.SeverityNumberInfo,
+					attributes: map[string]any{
+						"extraString":  "stringValue",
+						"extraNumber":  float64(2217),
+						"extraFloat":   float64(3.14),
+						"extraBoolean": true,
+						"extraNull":    nil,
+						"extraArrayOfStrings": []any{
+							"stringValue",
+							"stringValue",
+						},
+						"extraArrayOfNumbers": []any{
+							float64(2217),
+							float64(2217),
+						},
+						"extraArrayOfMixedTypes": []any{
+							"stringValue",
+							float64(2217),
+							true,
+							nil,
+						},
+						"extraArrayWithNesting": []any{
+							"stringValue",
+							[]any{
+								float64(2217),
+								[]any{
+									true, nil,
+								},
+							},
+						},
+						"extraObject": map[string]any{
+							"stringValue":  "stringValue",
+							"numberValue":  float64(2217),
+							"booleanValue": true,
+							"nullValue":    nil,
+						},
+						"extraObjectWithNesting": map[string]any{
+							"stringValue":  "stringValue",
+							"numberValue":  float64(2217),
+							"booleanValue": true,
+							"nullValue":    nil,
+							"arrayValue": []any{
+								"stringValue",
+								float64(2217),
+							},
+							"objectValue": map[string]any{
+								"stringValue": "stringValue",
+								"numberValue": float64(2217),
+							},
+						},
+					},
+				},
+			},
+			expectError: false,
+		},
+		{
+			desc: "function json with keeping reserved fields intact",
+			slice: []event{
+				{
+					Time: "2026-02-26T20:15:32.000Z",
+					Type: "function",
+					Record: map[string]any{
+						"timestamp": "2026-02-26T20:15:32.000Z",
+						"level":     "INFO",
+						"requestId": "79b4f56e-95b1-4643-9700-2807f4e6",
+						"message":   "Hello world, I am a function with overriden type field!",
+						"type":      "override",
+					},
+				},
+			},
+			expectedLogs: []logInfo{
+				{
+					logType:           "function",
+					timestamp:         "2026-02-26T20:15:32.000Z",
+					body:              "Hello world, I am a function with overriden type field!",
+					containsRequestId: true,
+					requestId:         "79b4f56e-95b1-4643-9700-2807f4e6",
+					severityText:      "Info",
+					severityNumber:    plog.SeverityNumberInfo,
+				},
+			},
+			expectError: false,
+		},
 		{
 			desc: "extension text",
 			slice: []event{
@@ -820,6 +952,13 @@ func TestCreateLogs(t *testing.T) {
 				require.Equal(t, expected.severityText, logRecord.SeverityText())
 				require.Equal(t, expected.severityNumber, logRecord.SeverityNumber())
 				require.Equal(t, expected.body, logRecord.Body().Str())
+
+				// Check expected attributes
+				for key, value := range expected.attributes {
+					attr, ok := logRecord.Attributes().Get(key)
+					require.True(t, ok, "expected attribute %s not found", key)
+					require.Equal(t, value, attr.AsRaw(), "expected attribute %s to have value %v, got %v", key, value, attr.AsRaw())
+				}
 			}
 		})
 	}