refactor: replace userdata_files with generic metadata_files map

Signed-off-by: Pratyush singhal <psinghal20@gmail.com>

builder/googlecompute/config.go

@@ -62,7 +62,7 @@ type Config struct {
 	Subnetwork                   string                         `mapstructure:"subnetwork"`
 	Tags                         []string                       `mapstructure:"tags"`
 	UseInternalIP                bool                           `mapstructure:"use_internal_ip"`
-	UserdataFile                 string                         `mapstructure:"userdata_file"`
+	MetadataFiles                map[string]string              `mapstructure:"metadata_files"`
 	Zone                         string                         `mapstructure:"zone"`
 
 	Account            AccountFile

builder/googlecompute/step_create_instance.go

@@ -45,10 +45,11 @@ func (c *Config) createInstanceMetadata(sourceImage *Image, sshPublicKey string)
 		instanceMetadata[StartupWrappedScriptKey] = wrappedStartupScript
 	}
 
-	if c.UserdataFile != "" {
+	// Read metadata from files specified with metadata_files
+	for key, value := range c.MetadataFiles {
 		var content []byte
-		content, err = ioutil.ReadFile(c.UserdataFile)
-		instanceMetadata["user-data"] = string(content)
+		content, err = ioutil.ReadFile(value)
+		instanceMetadata[key] = string(content)
 	}
 
 	if sourceImage.IsWindows() {