Quick and shit. Visit gitbook2pdf.fht.im
Thanks to https://www.v2ex.com/member/fuergaosi
Code can be found at https://github.com/imfht/gitbook2pdf.online and https://github.com/imfht/gitbook2pdf
阿里云上注册了 gitbook2pdf.online 发现没有实名不能解析... quick and shit 失败于是使用了一个自己的域名。