Docker daemon runs as root, writing to volume mounts leaves files unreadable for buildkite-agent

[lox]

If builds run docker commands and mount in volumes, files are written as root, due to Docker's root-only-ness.

This means that subsequent builds fail with permission errors because they can't git clean the files.

[lox]

More details here moby/moby#3124

[jeromegn]

I just stumbled on this very issue. My workaround is to build an image ADDing the files instead of mounting a volume on a generic image.

[lox]

A terrible hack that we have as a workaround is to use the docker socket to chown the files in a post-command hook:

#!/bin/bash
set -eu

docker run -it -v $(pwd):/project busybox chown -R 498.496 /project