switch glauth to struct tag based env config

ocs/pkg/command/root.go

@@ -86,12 +86,12 @@ func ParseConfig(c *cli.Context, cfg *config.Config) error {
 
 	// load all env variables relevant to the config in the current context.
 	envCfg := config.Config{}
-	if err := envdecode.Decode(&envCfg); err != nil {
+	if err := envdecode.Decode(&envCfg); err != nil && err.Error() != "none of the target fields were set from environment variables" {
 		return err
 	}
 
 	// merge environment variable config on top of the current config
-	if err := mergo.Merge(cfg, envCfg, mergo.WithOverride); err != nil && err.Error() != "none of the target fields were set from environment variables" {
+	if err := mergo.Merge(cfg, envCfg, mergo.WithOverride); err != nil {
 		return err
 	}