Add additional fingerprint error to check for when updating metadata (h…

…ashicorp#221)

google/metadata.go

@@ -3,12 +3,14 @@ package google
 import (
 	"fmt"
 	"log"
+	"strings"
 
 	"google.golang.org/api/compute/v1"
 )
 
 const FINGERPRINT_RETRIES = 10
-const FINGERPRINT_FAIL = "Invalid fingerprint."
+
+var FINGERPRINT_FAIL_ERRORS = []string{"Invalid fingerprint.", "Supplied fingerprint does not match current metadata fingerprint."}
 
 // Since the google compute API uses optimistic locking, there is a chance
 // we need to resubmit our updated metadata. To do this, you need to provide
@@ -17,11 +19,25 @@ func MetadataRetryWrapper(update func() error) error {
 	attempt := 0
 	for attempt < FINGERPRINT_RETRIES {
 		err := update()
-		if err != nil && err.Error() == FINGERPRINT_FAIL {
-			attempt++
-		} else {
+		if err == nil {
+			return nil
+		}
+
+		// Check to see if the error matches any of our fingerprint-related failure messages
+		var fingerprintError bool
+		for _, msg := range FINGERPRINT_FAIL_ERRORS {
+			if strings.Contains(err.Error(), msg) {
+				fingerprintError = true
+				break
+			}
+		}
+
+		if !fingerprintError {
+			// Something else went wrong, don't retry
 			return err
 		}
+
+		attempt++
 	}
 
 	return fmt.Errorf("Failed to update metadata after %d retries", attempt)