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ericcurtinericcurtin
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fix bind-mount failure on macOS Docker Desktop
Docker Desktop on macOS only shares specific directories with its Linux VM via VirtioFS ($HOME, /private, /Volumes, /tmp). Scripts installed to /usr/local/bin (e.g. via Homebrew) are not accessible, so Docker creates an empty directory placeholder in the VM. This makes /usr/bin/entrypoint a directory in the container, causing runc to fail with "is a directory". distrobox-create: on Darwin, copy distrobox-init, distrobox-export, and distrobox-host-exec to ~/.local/share/distrobox/ (always under $HOME, always VirtioFS-shared) before using them as bind-mount sources. distrobox-enter: the self-healing detection code reads .HostConfig.Binds, which Docker Desktop returns with a /host_mnt prefix (the VM's view of the VirtioFS mount). Strip this prefix on Darwin before checking file existence, preventing a spurious "mkdir: /host_mnt: Read-only file system" crash even for correctly-created containers. Signed-off-by: Eric Curtin <eric.curtin@docker.com>
1 parent c6cc6a3 commit 5fe219e

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‎distrobox‎

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@@ -62,6 +62,31 @@ distrobox_path="$(dirname "${0}")"
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distrobox_command="${1}"
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shift
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# On macOS with Docker Desktop, only paths under $HOME are shared with the
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# Docker Linux VM via VirtioFS. Scripts installed to /usr/local/bin (e.g.
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# via Homebrew) are not accessible, so Docker creates an empty directory
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# placeholder in the VM, causing "exec: /usr/bin/entrypoint: is a directory".
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#
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# Maintain a managed cache in ~/.local/share/distrobox/ (always under $HOME,
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# always VirtioFS-shared). Copy each script only when the installed version
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# is newer than the cached copy, so upgrades are picked up automatically.
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if [ "$(uname -s)" = "Darwin" ]; then
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_dd_data_dir="${XDG_DATA_HOME:-"${HOME}/.local/share"}/distrobox"
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mkdir -p "${_dd_data_dir}"
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for _dd_script in distrobox-init distrobox-export distrobox-host-exec; do
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_dd_src="${distrobox_path}/${_dd_script}"
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[ ! -f "${_dd_src}" ] && _dd_src="$(command -v "${_dd_script}" 2> /dev/null || true)"
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if [ -f "${_dd_src}" ]; then
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_dd_dst="${_dd_data_dir}/${_dd_script}"
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if [ ! -f "${_dd_dst}" ] || [ "${_dd_src}" -nt "${_dd_dst}" ]; then
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cp -f "${_dd_src}" "${_dd_dst}"
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chmod +x "${_dd_dst}"
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fi
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fi
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done
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unset _dd_script _dd_src _dd_dst _dd_data_dir
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fi
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# Simple wrapper to the distrobox utilities.
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# We just detect the 1st argument and launch the matching distrobox utility.
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case "${distrobox_command}" in

‎distrobox-create‎

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@@ -102,6 +102,25 @@ distrobox_hostexec_path="$(cd "$(dirname "${0}")" && pwd)/distrobox-host-exec"
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[ ! -e "${distrobox_export_path}" ] && distrobox_export_path="$(command -v distrobox-export)"
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[ ! -e "${distrobox_genentry_path}" ] && distrobox_genentry_path="$(command -v distrobox-generate-entry)"
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[ ! -e "${distrobox_hostexec_path}" ] && distrobox_hostexec_path="$(command -v distrobox-host-exec)"
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# On macOS with Docker Desktop, prefer the managed cache under
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# ~/.local/share/distrobox/ (always VirtioFS-shared) over the installed
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# paths. The main distrobox entry point keeps the cache up-to-date; when
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# distrobox-create is invoked directly the cache may also exist from a prior
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# run via the main entry point.
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if [ "$(uname -s)" = "Darwin" ]; then
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_dd_data_dir="${XDG_DATA_HOME:-"${HOME}/.local/share"}/distrobox"
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for _dd_script in distrobox-init distrobox-export distrobox-host-exec; do
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_dd_cached="${_dd_data_dir}/${_dd_script}"
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if [ -f "${_dd_cached}" ]; then
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case "${_dd_script}" in
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distrobox-init) distrobox_entrypoint_path="${_dd_cached}" ;;
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distrobox-export) distrobox_export_path="${_dd_cached}" ;;
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distrobox-host-exec) distrobox_hostexec_path="${_dd_cached}" ;;
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esac
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fi
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done
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unset _dd_script _dd_cached _dd_data_dir
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fi
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# If the user runs this script as root in a login shell, set rootful=1.
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# There's no need for them to pass the --root flag option in such cases.
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[ "${container_user_uid}" -eq 0 ] && rootful=1 || rootful=0

‎distrobox-enter‎

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@@ -689,6 +689,45 @@ if [ "${container_status}" != "running" ]; then
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# Here, we save the timestamp before launching the start command, so we can
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# be sure we're working with this very same session of logs later.
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log_timestamp="$(date -u +%FT%T).000000000+00:00"
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# On macOS with Docker Desktop + VirtioFS, only paths under $HOME and a
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# few system directories (/private, /Volumes) are shared with the Docker
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# VM. If distrobox-init lives outside those paths (e.g. /usr/local/bin
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# from Homebrew), Docker cannot find the bind-mount source in the VM and
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# creates an empty directory placeholder instead, causing the container
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# to fail with "exec: /usr/bin/entrypoint: is a directory".
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#
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# Detect this by reading the stored bind-mount source from
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# .HostConfig.Binds (the container config, not .Mounts which is empty
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# for stopped containers) and checking whether it is accessible as a
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# file. If it is not, copy the current distrobox-init to
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# ~/.local/share/distrobox/ (always under $HOME, always shared) and
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# write it to the stored source path so the bind-mount resolves to a
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# file when the container starts.
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entrypoint_source="$(${container_manager} inspect --type container \
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--format '{{range .HostConfig.Binds}}{{printf "%s\n" .}}{{end}}' \
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"${container_name}" 2> /dev/null |
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grep ':/usr/bin/entrypoint' | cut -d: -f1)"
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# On macOS with Docker Desktop, .HostConfig.Binds may store paths with a
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# /host_mnt prefix (Docker Desktop's VirtioFS mount prefix in the Linux VM).
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# Strip the prefix to get the actual macOS path for the file-existence check.
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entrypoint_source_check="${entrypoint_source}"
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if [ "$(uname -s)" = "Darwin" ]; then
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entrypoint_source_check="${entrypoint_source_check#/host_mnt}"
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fi
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if [ -n "${entrypoint_source}" ] && [ ! -f "${entrypoint_source_check}" ]; then
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distrobox_entrypoint_path="$(cd "$(dirname "${0}")" && pwd)/distrobox-init"
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[ ! -f "${distrobox_entrypoint_path}" ] &&
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distrobox_entrypoint_path="$(command -v distrobox-init 2> /dev/null)"
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if [ -f "${distrobox_entrypoint_path}" ]; then
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# Remove Docker's empty-directory placeholder (if present) and
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# replace it with the actual script so the bind-mount works.
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[ -d "${entrypoint_source}" ] && rmdir "${entrypoint_source}" 2> /dev/null
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mkdir -p "$(dirname "${entrypoint_source}")"
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cp "${distrobox_entrypoint_path}" "${entrypoint_source}"
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chmod +x "${entrypoint_source}"
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fi
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fi
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unset entrypoint_source entrypoint_source_check
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${container_manager} start "${container_name}" > /dev/null
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#
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# Check if the container is going in error status earlier than the

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