... then I suppose Selfdock is for you.
* Does not give or require root.
* Fast: Does not write to disk.
* Fast: Does not allocate memory.
* No daemon.
* Does not give or require root.
* Fast: Does not write to disk.
* Fast: Does not allocate memory.
* No daemon.
Interesting philosophy, it will pose some issues when replicating a Docker 'build' like system though. But that could be separated from the 'run' system with cached layers.
edit: Btw, Docker also seems to support this: https://nickjanetakis.com/blog/docker-tip-55-creating-read-o.... Also allowing explicit creation of writable tmpfs mountpoints.