Docker build fails to mount a single file

[RocketJas]

There is an issue with the version of docker on the latest AzureLinux container image

Docker build failing to mount single file via bind
When running docker build (with DOCKER_BUILDKIT=1) on the mariner image, the RUN stage fails when attempting to mount a single file --mount=type=bind with the error

executor failed running [/bin/bash -euxc bash tmp/test_mount.sh]: failed to mount /var/lib/docker/tmp/buildkit-mount3000888503: [{Type:bind Source:/proc/self/fd/25 Options:[rbind ro]}]: not a directory

To Reproduce
Steps to reproduce the behavior:

1. Ensure you are running on a mariner OS
2. Clone repo
3. Set the Environment Variable export DOCKER_BUILDKIT=1
4. From the root directory run docker build -t test_dockerfile_mariner -f test.dockerfile .

[mattsheerin]

I hit this too. With the help of dnf history I managed to inspect my recent upgrades.

• sudo dnf downgrade moby-cli-20.10.27-3.cm2.x86_64 didn't seem to help.
• sudo dnf downgrade moby-cli-20.10.27-2.cm2.x86_64 still didn't fix it.
• sudo dnf downgrade moby-engine-20.10.27-1.cm2.x86_64 worked, I think I had to restart docker too. Maybe the above downgrades aren't needed but I'm holding off upgrading again until this is fixed.

[mandeepsplaha]

Hi @RocketJas, the link to the repo doesn't seem valid anymore. Do you still have this issue? I can confirm that some of our builds, we do have --mount=type=bind usage in Mariner and it works successfully. We do install moby-buildx package for this functionality.

[mattsheerin]

I recently hit a different problem and installed moby-buildx as a solution. Today I tried the problematic build for the first time in a while, this time with all the latest moby RPMs, and still have this issue.

In your builds, do you use --mount=type=bind for files or directories? I seem to only have the problem for mounting individual files, but I've not tested that extensively.

Solution for me is still:

sudo dnf downgrade moby-engine-20.10.27-1.cm2.x86_64
sudo systemctl restart docker