Docker not seeing file modifications on bind mount

Docker Desktop
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1

My expectation is that with a bind mount file modifications on the host machine are reflected in the container with the bind mount. This appears to not be working with docker on windows. I have not yet been able to find other reports on this issue. Can anyone shed any light on this issue?

The script below loops and cats a file repeatedly. If the file C:\work\testfile.txt is modified, I would expect the updates to show 3 seconds later with the next cat. However, this does not occur. In fact, the content of c:\work\testfile.txt seems locked in until a docker restart. It is not sufficient to run this command again.

docker run --mount type=bind,source=/,target=/mnt/external alpine sh -c "for i in 1 2 3 4 5 6 7 8 9 0 10 11 12 13 14 15 16 17 18; do sleep 3; cat /mnt/external/host_mnt/c/work/testfile.txt; done"

Version info:
Windows 10 Pro 1909 OS build 18363.720
Docker Engine v19.03.8

2

For the record, I have since discovered that a “root” mount in windows seems to be problematic. For instance, the loop below does see updates to testfile.txt immediately.

docker run --mount type=bind,source=c:/work/,target=/mnt/external alpine sh -c "for i in 1 2 3 4 5 6 7 8 9 0 10 11 12 13 14 15 16 17 18; do sleep 3; cat /mnt/external/testfile1.txt; done"

We arrived at the example in my first post in analogy with a linux machine, but the better way in windows is to mount each drive letter separately if that is what you are after.