Docker Engine unable to start when host path for File share is not available

[pirate]

Description

This took a long time for me to figure out:

If a File Share disappears on a macOS host because the drive was removed or the folder was deleted, the Docker Engine becomes unable to start and provides no error message or indication as to why.

I was going mad trying to figure out why it wouldn't start, I almost completely uninstalled Docker before I tried turning off literally all optional features and removing all the file share mounts in a final act of desperation.

Reproduce

1. Settings > Resources > File sharing > Virtual file shares > +
   Add a file share mount on a removable drive or network mount (e.g. /Volumes/USB-DRIVE)
2. Quit Docker Desktop
3. Remove/eject the external drive from your system (e.g. Finder.app > USB-DRIVE > Eject)
4. Open Docker Desktop
5. It shows Docker is starting... but never actually starts, and the menubar indicates the engine is stopped. It stays stuck in this state with no details as to why it's failing to start. Restarting the engine or rebooting also doesn't help.

Expected behavior

It should just ignore that directory or present it as an empty volume with no files inside.

Imo it shouldn't prevent Docker from starting or even show any error message, as there are many situations where you may want to share a transient folder present from a network share or USB drive that's not always mounted, and having to remove/re-add it every time it appears/disappears would be very annoying.

Think about all the companies that have NFS/SMB shares or all the users that might want to use files on a USB drive that are only available at their office, but then they go home and Docker bricks itself when they're not available.

docker version

Client:
 Cloud integration: v1.0.35+desktop.13
 Version:           26.0.0
 API version:       1.45
 Go version:        go1.21.8
 Git commit:        2ae903e
 Built:             Wed Mar 20 15:14:46 2024
 OS/Arch:           darwin/arm64
 Context:           desktop-linux

Server: Docker Desktop 4.29.0 (145265)
 Engine:
  Version:          26.0.0
  API version:      1.45 (minimum version 1.24)
  Go version:       go1.21.8
  Git commit:       8b79278
  Built:            Wed Mar 20 15:18:02 2024
  OS/Arch:          linux/arm64
  Experimental:     false
 containerd:
  Version:          1.6.28
  GitCommit:        ae07eda36dd25f8a1b98dfbf587313b99c0190bb
 runc:
  Version:          1.1.12
  GitCommit:        v1.1.12-0-g51d5e94
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

docker info

Client:
 Version:    26.0.0
 Context:    desktop-linux
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.13.1-desktop.1
    Path:     /Volumes/NVME/Users/squash/.docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.26.1-desktop.1
    Path:     /Volumes/NVME/Users/squash/.docker/cli-plugins/docker-compose
  debug: Get a shell into any image or container. (Docker Inc.)
    Version:  0.0.27
    Path:     /Volumes/NVME/Users/squash/.docker/cli-plugins/docker-debug
  dev: Docker Dev Environments (Docker Inc.)
    Version:  v0.1.2
    Path:     /Volumes/NVME/Users/squash/.docker/cli-plugins/docker-dev
  extension: Manages Docker extensions (Docker Inc.)
    Version:  v0.2.23
    Path:     /Volumes/NVME/Users/squash/.docker/cli-plugins/docker-extension
  feedback: Provide feedback, right in your terminal! (Docker Inc.)
    Version:  v1.0.4
    Path:     /Volumes/NVME/Users/squash/.docker/cli-plugins/docker-feedback
  init: Creates Docker-related starter files for your project (Docker Inc.)
    Version:  v1.1.0
    Path:     /Volumes/NVME/Users/squash/.docker/cli-plugins/docker-init
  sbom: View the packaged-based Software Bill Of Materials (SBOM) for an image (Anchore Inc.)
    Version:  0.6.0
    Path:     /Volumes/NVME/Users/squash/.docker/cli-plugins/docker-sbom
  scout: Docker Scout (Docker Inc.)
    Version:  v1.6.3
    Path:     /Volumes/NVME/Users/squash/.docker/cli-plugins/docker-scout
WARNING: Plugin "/Volumes/NVME/Users/squash/.docker/cli-plugins/docker-scan" is not valid: failed to fetch metadata: fork/exec /Volumes/NVME/Users/squash/.docker/cli-plugins/docker-scan: no such file or directory

Server:
 Containers: 26
  Running: 6
  Paused: 0
  Stopped: 20
 Images: 34
 Server Version: 26.0.0
 Storage Driver: stargz
  driver-type: io.containerd.snapshotter.v1
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: ae07eda36dd25f8a1b98dfbf587313b99c0190bb
 runc version: v1.1.12-0-g51d5e94
 init version: de40ad0
 Security Options:
  seccomp
   Profile: unconfined
  cgroupns
 Kernel Version: 6.6.22-linuxkit
 Operating System: Docker Desktop
 OSType: linux
 Architecture: aarch64
 CPUs: 5
 Total Memory: 7.755GiB
 Name: docker-desktop
 ID: db9bc8bc-f4d6-4bf1-9100-a88bf4292336
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 HTTP Proxy: http.docker.internal:3128
 HTTPS Proxy: http.docker.internal:3128
 No Proxy: hubproxy.docker.internal
 Labels:
  com.docker.desktop.address=unix:///Volumes/NVME/Users/squash/Library/Containers/com.docker.docker/Data/docker-cli.sock
 Experimental: false
 Insecure Registries:
  hubproxy.docker.internal:5555
  127.0.0.0/8
 Live Restore Enabled: false

WARNING: daemon is not using the default seccomp profile

Diagnostics ID

5EEC1A9A-F159-4A04-A241-E60E50C218B5/20240501001245

Additional Info

macOS 14.4.1 on M1 Apple Silicon

[pirate]

Possibly related:

• Docker Desktop can't start when VirtioFS enabled and have shared dir #7003
• Trying to mount directories in Docker #7105
• Failing to mount local volume in docker desktop 4.28.0 #7227
• fatal error occur every time i open docker (mac) #7234
• No longer able to add paths to Docker Desktop File Sharing #7012
• Error response from daemon: Mounts denied: The path **** is not shared from the host and is not known to Docker. #6759
• Docker for Mac hangs while starting up. Stuck on "Docker Desktop is Starting" #5113
• Docker for Mac is stucked at starting #6135
• Unable to start docker desktop on a M1 Mac #6902
• Unable to start up MAC M1 (Silicon) Docker Desktop after Interactive Installation #6713
• Docker desktop won't start after update #6914 (comment)
• Docker 4.15 Mac M1 doesn't start after switching on VirtioFS #6628 (comment)
• With VirtioFS, the containers do not work properly #6630
• Docker Desktop for Mac stuck on Starting... (Mac m1) #6649
• Bind mounts with shared mount propogation don't work #3431 (comment)