Comzyh

使用Alpine镜像启动会提示 ``` panic: user: Current not implemented on linux/amd64 goroutine 1 [running]: github.com/sipt/shuttle/extension/config.init.0() /Users/sipt/Documents/GOPATH/src/github.com/sipt/shuttle/extension/config/config_path.go:17 +0x20f ``` 经查，https://github.com/sipt/shuttle/blob/e7b367e12827d4d81acb5deeb7d027b172215fb4/extension/config/config_path_linux.go#L10 中 `user.Current()` 依赖 "$USER" 环境变量，一般docker环境并无这个环境变量，所以会报错; 如果`ShuttleHomeDir`变量仅在upgrade的时候使用，能否在upgrade的时候再手动调用相关函数，不写在`init()` 中？ https://github.com/sipt/shuttle/blob/e7b367e12827d4d81acb5deeb7d027b172215fb4/extension/config/config_path.go#L12 同时给出一个临时的解决方法: 在Docker container 中添加一个环境变量`USER=root`