alpine是比較小巧的鏡像，占用存儲空間小，更新apline源為阿里雲的源提高更新速度
更新時要注意版本，3.10要對應3.10的源哦
Dockerfile寫法：
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