Adds the ability to use SQS FIFO queues.

All SQS FIFO queues have the `.fifo` suffix at the end of their URL - this is how we determine if we are using a FIFO queue or not. The `MessageGroupId` (A required field for FIFO) is set using the key & id of the event's message.

Note: This commit does not add the the `MessageDeduplicationID` so the FIFO queue must have content-based deduplication enabled.

internal/endpoint/sqs.go

@@ -6,6 +6,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/tidwall/gjson"
+
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/credentials"
 	"github.com/aws/aws-sdk-go/aws/session"
@@ -108,11 +110,17 @@ func (conn *SQSConn) Send(msg string) error {
 	}
 
 	queueURL := conn.generateSQSURL()
-	// Send message
+	// Create message
 	sendParams := &sqs.SendMessageInput{
 		MessageBody: aws.String(msg),
 		QueueUrl:    aws.String(queueURL),
 	}
+	if isFifoQueue(queueURL) {
+		key := gjson.Get(msg, "key")
+		id := gjson.Get(msg, "id")
+		keyValue := fmt.Sprintf("%s#%s", key.String(), id.String())
+		sendParams.MessageGroupId = aws.String(keyValue)
+	}
 	_, err := conn.svc.SendMessage(sendParams)
 	if err != nil {
 		fmt.Println(err)
@@ -145,3 +153,7 @@ func sqsRegionFromPlainURL(s string) string {
 	}
 	return ""
 }
+
+func isFifoQueue(s string) bool {
+	return strings.HasSuffix(s, ".fifo")
+}