alpine是比较小巧的镜像，占用存储空间小，更新apline源为阿里云的源提高更新速度
更新时要注意版本，3.10要对应3.10的源哦
Dockerfile写法：
FROM alpine:3.10
RUN echo http://mirrors.aliyun.com/alpine/v3.10/main/ > /etc/apk/repositories && \
echo http://mirrors.aliyun.com/alpine/v3.10/community/ >> /etc/apk/repositories
RUN apk update && apk upgrade