I actually have a problem with a Dockerfile from https://github.com/asciimoo/searx (commit 6a158ca2d2c5fdec597f1025c58fad90a57312dc). There the code
COPY requirements.txt .
creates a “Not a directory” error with my btrfs based docker system. The developer of this tool has no problems with overlay filesystem. Are there known differences between btrfs, aufs, or overlay?
I am running productive docker systems with -s btrfs (so B). But this more or less implies that the whole system is running with btrfs (A)
But also the machine I build the containers with is a btrfs laptop (A) with running docker -s btrfs (B) - and this is the machine I tried to CP file /path which failed but seems to work with overlay (I guess the developer uses default docker settings, no -s btrfs neither a btrfs system).