ParseUserData: return nil on empty input string

coreos-cloudinit.go

@@ -115,7 +115,7 @@ func main() {
 	env := initialize.NewEnvironment("/", ds.ConfigRoot(), workspace, convertNetconf, sshKeyName, subs)
 
 	var ccm, ccu *initialize.CloudConfig
-	var script system.Script
+	var script *system.Script
 	if ccm, err = initialize.ParseMetaData(string(metadataBytes)); err != nil {
 		fmt.Printf("Failed to parse meta-data: %v\n", err)
 		die()
@@ -128,7 +128,7 @@ func main() {
 		case *initialize.CloudConfig:
 			ccu = t
 		case system.Script:
-			script = t
+			script = &t
 		}
 	}
 
@@ -155,7 +155,7 @@ func main() {
 	}
 
 	if script != nil {
-		if err = runScript(script, env); err != nil {
+		if err = runScript(*script, env); err != nil {
 			fmt.Printf("Failed to run script: %v\n", err)
 			die()
 		}

initialize/user_data.go

@@ -9,6 +9,9 @@ import (
 )
 
 func ParseUserData(contents string) (interface{}, error) {
+	if len(contents) == 0 {
+		return nil, nil
+	}
 	header := strings.SplitN(contents, "\n", 2)[0]
 
 	// Explicitly trim the header so we can handle user-data from

initialize/user_data_test.go

@@ -47,3 +47,12 @@ func TestParseConfigCRLF(t *testing.T) {
 		t.Error("Parsed incorrect number of SSH keys")
 	}
 }
+
+func TestParseConfigEmpty(t *testing.T) {
+	i, e := ParseUserData(``)
+	if i != nil {
+		t.Error("ParseUserData of empty string returned non-nil unexpectedly")
+	} else if e != nil {
+		t.Error("ParseUserData of empty string returned error unexpectedly")
+	}
+}