Changing Headers definition from byte to int8 for KafkaRecord (#506)

Author: milovacb

events/kafka.go

@@ -2,6 +2,10 @@
 
 package events
 
+import (
+	"encoding/json"
+)
+
 type KafkaEvent struct {
 	EventSource      string                   `json:"eventSource"`
 	EventSourceARN   string                   `json:"eventSourceArn"`
@@ -10,12 +14,37 @@ type KafkaEvent struct {
 }
 
 type KafkaRecord struct {
-	Topic         string                `json:"topic"`
-	Partition     int64                 `json:"partition"`
-	Offset        int64                 `json:"offset"`
-	Timestamp     MilliSecondsEpochTime `json:"timestamp"`
-	TimestampType string                `json:"timestampType"`
-	Key           string                `json:"key,omitempty"`
-	Value         string                `json:"value,omitempty"`
-	Headers       []map[string][]byte   `json:"headers"`
+	Topic         string                       `json:"topic"`
+	Partition     int64                        `json:"partition"`
+	Offset        int64                        `json:"offset"`
+	Timestamp     MilliSecondsEpochTime        `json:"timestamp"`
+	TimestampType string                       `json:"timestampType"`
+	Key           string                       `json:"key,omitempty"`
+	Value         string                       `json:"value,omitempty"`
+	Headers       []map[string]JSONNumberBytes `json:"headers"`
+}
+
+// JSONNumberBytes represents array of bytes in Headers field.
+type JSONNumberBytes []byte
+
+// MarshalJSON converts byte array into array of signed integers.
+func (b JSONNumberBytes) MarshalJSON() ([]byte, error) {
+	signedNumbers := make([]int8, len(b))
+	for i, value := range b {
+		signedNumbers[i] = int8(value)
+	}
+	return json.Marshal(signedNumbers)
+}
+
+// UnmarshalJSON converts a given json with potential negative values into byte array.
+func (b *JSONNumberBytes) UnmarshalJSON(data []byte) error {
+	var signedNumbers []int8
+	if err := json.Unmarshal(data, &signedNumbers); err != nil {
+		return err
+	}
+	*b = make(JSONNumberBytes, len(signedNumbers))
+	for i, value := range signedNumbers {
+		(*b)[i] = byte(value)
+	}
+	return nil
 }

events/kafka_test.go

@@ -20,6 +20,14 @@ func TestKafkaEventMarshaling(t *testing.T) {
 		t.Errorf("could not unmarshal event. details: %v", err)
 	}
 
+	// expected values for header
+	var headerValues [5]byte
+	headerValues[0] = 118
+	headerValues[1] = 220 // -36 + 256
+	headerValues[2] = 0
+	headerValues[3] = 127
+	headerValues[4] = 128 // -128 + 256
+
 	assert.Equal(t, inputEvent.BootstrapServers, "b-2.demo-cluster-1.a1bcde.c1.kafka.us-east-1.amazonaws.com:9092,b-1.demo-cluster-1.a1bcde.c1.kafka.us-east-1.amazonaws.com:9092")
 	assert.Equal(t, inputEvent.EventSource, "aws:kafka")
 	assert.Equal(t, inputEvent.EventSourceARN, "arn:aws:kafka:us-west-2:012345678901:cluster/ExampleMSKCluster/e9f754c6-d29a-4430-a7db-958a19fd2c54-4")
@@ -33,8 +41,9 @@ func TestKafkaEventMarshaling(t *testing.T) {
 			for _, header := range record.Headers {
 				for key, value := range header {
 					assert.Equal(t, key, "headerKey")
-					headerValue := string(value)
-					assert.Equal(t, headerValue, "headerValue")
+					for i, headerValue := range value {
+						assert.Equal(t, headerValue, headerValues[i])
+					}
 				}
 			}
 		}

events/testdata/kafka-event.json

@@ -14,7 +14,13 @@
           "value": "OGQ1NTk2YjQtMTgxMy00MjM4LWIyNGItNmRhZDhlM2QxYzBj",
           "headers": [
             {
-              "headerKey": "aGVhZGVyVmFsdWU="
+              "headerKey": [
+                118,
+                -36,
+                0,
+                127,
+                -128
+              ]
             }
           ]
         }