Refactor queue creation and attribute handling

queue.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"os"
 	"strconv"
 
 	"github.com/aws/aws-sdk-go/aws"
@@ -17,7 +18,16 @@ import (
 
 const (
 	longPollingWaitTimeSeconds = 20
-	queuePolicy                = `
+)
+
+var queuePolicy = loadQueuePolicy()
+
+func loadQueuePolicy() string {
+	filePath := "/etc/lifecycled/queue_policy.json"
+	policy, err := os.ReadFile(filePath)
+	if err != nil {
+		// Handle the error, e.g., by providing a default policy
+		return `
 {
   "Version":"2012-10-17",
   "Statement":[
@@ -35,7 +45,9 @@ const (
   ]
 }
 `
-)
+	}
+	return string(policy)
+}
 
 // SQSClient for testing purposes
 //go:generate mockgen -destination=mocks/mock_sqs_client.go -package=mocks github.com/buildkite/lifecycled SQSClient
@@ -69,16 +81,24 @@ func NewQueue(queueName, topicArn string, sqsClient SQSClient, snsClient SNSClie
 
 // Create the SQS queue.
 func (q *Queue) Create() error {
+	attributes := map[string]*string{
+		"Policy":                        aws.String(fmt.Sprintf(queuePolicy, q.topicArn)),
+		"ReceiveMessageWaitTimeSeconds": aws.String(strconv.Itoa(longPollingWaitTimeSeconds)),
+	}
+
+	kmsMasterKeyID := os.Getenv("KMS_MASTER_KEY_ID")
+	if kmsMasterKeyID != "" {
+		attributes["KMSMasterKeyId"] = aws.String(kmsMasterKeyID)
+	}
+
 	out, err := q.sqsClient.CreateQueue(&sqs.CreateQueueInput{
-		QueueName: aws.String(q.name),
-		Attributes: map[string]*string{
-			"Policy":                        aws.String(fmt.Sprintf(queuePolicy, q.topicArn)),
-			"ReceiveMessageWaitTimeSeconds": aws.String(strconv.Itoa(longPollingWaitTimeSeconds)),
-		},
+		QueueName:  aws.String(q.name),
+		Attributes: attributes,
 	})
 	if err != nil {
 		return err
 	}
+
 	q.url = aws.StringValue(out.QueueUrl)
 	return nil
 }