consul: Adding util method to generate a UUID

consul/util.go

@@ -1,6 +1,7 @@
 package consul
 
 import (
+	crand "crypto/rand"
 	"encoding/binary"
 	"fmt"
 	"github.com/hashicorp/serf/serf"
@@ -160,3 +161,18 @@ func runtimeStats() map[string]string {
 		"cpu_count":  strconv.FormatInt(int64(runtime.NumCPU()), 10),
 	}
 }
+
+// generateUUID is used to generate a random UUID
+func generateUUID() string {
+	buf := make([]byte, 16)
+	if _, err := crand.Read(buf); err != nil {
+		panic(fmt.Errorf("failed to read random bytes: %v", err))
+	}
+
+	return fmt.Sprintf("%08x-%04x-%04x-%04x-%12x",
+		buf[0:4],
+		buf[4:6],
+		buf[6:8],
+		buf[8:10],
+		buf[10:16])
+}

consul/util_test.go

@@ -2,6 +2,7 @@ package consul
 
 import (
 	"github.com/hashicorp/serf/serf"
+	"regexp"
 	"testing"
 )
 
@@ -75,3 +76,19 @@ func TestByteConversion(t *testing.T) {
 		t.Fatalf("no match")
 	}
 }
+
+func TestGenerateUUID(t *testing.T) {
+	prev := generateUUID()
+	for i := 0; i < 100; i++ {
+		id := generateUUID()
+		if prev == id {
+			t.Fatalf("Should get a new ID!")
+		}
+
+		matched, err := regexp.MatchString(
+			"[\\da-f]{8}-[\\da-f]{4}-[\\da-f]{4}-[\\da-f]{4}-[\\da-f]{12}", id)
+		if !matched || err != nil {
+			t.Fatalf("expected match %s %v %s", id, matched, err)
+		}
+	}
+}