docker清理空间
Docker - 解决/var/lib/docker/overlay2占用很大、容器无法启动问题(清理磁盘)
https://www.hangge.com/blog/cache/detail_2555.html
Docker overlay2占用大量磁盘空间解决办法
http://blog.hcodeclass.com/archives/dockeroverlay2-zhan-yong-da-liang-ci-pan-kong-jian-jie-jue-ban-fa
清空日志
cd /var/lib/docker/containers/xxx/xxx-json.log
https://blog.51cto.com/u_39029/7322573