fup: add bucket-url flag for specifying storage

This allows setting the persistent storage location to save files into.

NOTE: defaults to mem:// for development purposes, which... is gonna be a bad
time.

web/fup/cmd/root.go

@@ -13,6 +13,7 @@ import (
 
 var (
 	cfgFile   string
+	bucketURL string
 
 	rootCmd = &cobra.Command{
 		Use:   "fup",
@@ -29,6 +30,8 @@ func init() {
 	cobra.OnInitialize(initConfig)
 
 	rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file")
+	rootCmd.PersistentFlags().StringVar(&bucketURL, "bucket-url", "mem://", "gocloud.dev-compatible URL to use for file storage")
+	viper.BindPFlag("storage.bucketURL", rootCmd.PersistentFlags().Lookup("bucket-url"))
 }
 
 func initConfig() {