sed -i "s|/home/yuqing/fastdfs|/var/local/fdfs/tracker|g" /etc/fdfs/tracker.conf \

Step 3/15 : ENV HOME /root
---> Running in 6160fda9f086
---> 483c34765823
Removing intermediate container 6160fda9f086
Step 4/15 : RUN apk update && apk add --no-cache git gcc libc-dev make automake autoconf libtool pcre pcre-dev zlib zlib-dev openssl-dev wget vim --repository https://mirrors.tuna.tsinghua.edu.cn/alpine/v3.6/main
---> Running in 3adbe2b7c3e5

fetch http://dl-cdn.alpinelinux.org/alpine/v3.6/main/x86_64/APKINDEX.tar.gz
可以看到上面还是到了alpinelinux.org中下载，而这里会很缓慢。。。。

可以试着在 安装准备前增加下面这段语句

RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.ustc.edu.cn/g' /etc/apk/repositories

结果如下：

Step 5/16 : RUN apk update && apk add --no-cache git gcc libc-dev make automake autoconf libtool pcre pcre-dev zlib zlib-dev openssl-dev wget vim --repository https://mirrors.tuna.tsinghua.edu.cn/alpine/v3.6/main
---> Running in 55a80ed1aef0

fetch http://mirrors.ustc.edu.cn/alpine/v3.6/main/x86_64/APKINDEX.tar.gz

这样就跳到ustc上下载了 会快很多