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

重装docker后无法删除原来的镜像
cd /var/lib/docker/image/overlay2/imagedb/content/sha256
https://blog.csdn.net/justlpf/article/details/131972965