Add transform feature to rename keys from Vault

main.go

@@ -28,8 +28,9 @@ var (
 		TokenAuth struct {
 			Token string `flag:"vault-token" env:"VAULT_TOKEN" vardefault:"vault-token" description:"Specify a token to use instead of app-id auth"`
 		}
-		Export         bool `flag:"export,e" default:"false" description:"Show export statements instead of running the command specified"`
+		Export         bool     `flag:"export,e" default:"false" description:"Show export statements instead of running the command specified"`
-		VersionAndExit bool `flag:"version" default:"false" description:"Print program version and exit"`
+		Transform      []string `flag:"transform,t" default:"" description:"Translates keys to different names (oldkey=newkey)"`
+		VersionAndExit bool     `flag:"version" default:"false" description:"Print program version and exit"`
 	}{}
 	version = "dev"
 )
@@ -122,23 +123,36 @@ func main() {
 		log.Fatalf("Unable to fetch data: %s", err)
 	}
 
+	transformMap := env.ListToMap(cfg.Transform)
+
+	envData := map[string]string{}
+	for k, v := range data.Data {
+		key := k
+		if newKey, ok := transformMap[key]; ok {
+			key = newKey
+		}
+		envData[key] = v.(string)
+	}
+
 	if cfg.Export {
-		for k, v := range data.Data {
+		for k, v := range envData {
 			fmt.Printf("export %s=\"%s\"\n", k, v)
 		}
 		return
 	}
 
 	emap := env.ListToMap(os.Environ())
-	for k, v := range data.Data {
+	for k, v := range emap {
-		emap[k] = v.(string)
+		if _, ok := envData[k]; !ok {
+			envData[k] = v
+		}
 	}
 
 	cmd := exec.Command(rconfig.Args()[2], rconfig.Args()[3:]...)
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
 	cmd.Stdin = os.Stdin
-	cmd.Env = env.MapToList(emap)
+	cmd.Env = env.MapToList(envData)
 	if err := cmd.Run(); err != nil {
 		log.Fatal("Command exitted unclean (code != 0)")
 	}