No dm_mod kernel module in Docker Desktop for Mac

[tazle]

Description

This is a duplicate of #4549 which is claimed to have been fixed at some point, but seems to have reoccurred.

I'm unable to run kpartx in a container because /dev/mapper/control is missing, and the module is not available for loading in the docker host.

Reproduce

1. docker run -it --rm --privileged --pid=host justincormack/nsenter1 /sbin/modprobe dm_mod

Expected behavior

Expected to have dm_mod present so that containers can use loopback mounts in containers.

docker version

$ docker version
Client:
 Cloud integration: v1.0.35+desktop.10
 Version:           25.0.2
 API version:       1.44
 Go version:        go1.21.6
 Git commit:        29cf629
 Built:             Thu Feb  1 00:18:45 2024
 OS/Arch:           darwin/arm64
 Context:           desktop-linux

Server: Docker Desktop 4.27.1 (136059)
 Engine:
  Version:          25.0.2
  API version:      1.44 (minimum version 1.24)
  Go version:       go1.21.6
  Git commit:       fce6e0c
  Built:            Thu Feb  1 00:23:21 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

$ docker info
Client:
 Version:    25.0.2
 Context:    desktop-linux
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.12.1-desktop.4
    Path:     /Users/tuure/.docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.24.3-desktop.1
    Path:     /Users/tuure/.docker/cli-plugins/docker-compose
  debug: Get a shell into any image or container. (Docker Inc.)
    Version:  0.0.22
    Path:     /Users/tuure/.docker/cli-plugins/docker-debug
  dev: Docker Dev Environments (Docker Inc.)
    Version:  v0.1.0
    Path:     /Users/tuure/.docker/cli-plugins/docker-dev
  extension: Manages Docker extensions (Docker Inc.)
    Version:  v0.2.21
    Path:     /Users/tuure/.docker/cli-plugins/docker-extension
  feedback: Provide feedback, right in your terminal! (Docker Inc.)
    Version:  v1.0.4
    Path:     /Users/tuure/.docker/cli-plugins/docker-feedback
  init: Creates Docker-related starter files for your project (Docker Inc.)
    Version:  v1.0.0
    Path:     /Users/tuure/.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:     /Users/tuure/.docker/cli-plugins/docker-sbom
  scout: Docker Scout (Docker Inc.)
    Version:  v1.3.0
    Path:     /Users/tuure/.docker/cli-plugins/docker-scout
WARNING: Plugin "/Users/tuure/.docker/cli-plugins/docker-scan" is not valid: failed to fetch metadata: fork/exec /Users/tuure/.docker/cli-plugins/docker-scan: no such file or directory

Server:
 Containers: 75
  Running: 2
  Paused: 0
  Stopped: 73
 Images: 163
 Server Version: 25.0.2
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Using metacopy: false
  Native Overlay Diff: true
  userxattr: false
 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: 6.6.12-linuxkit
 Operating System: Docker Desktop
 OSType: linux
 Architecture: aarch64
 CPUs: 10
 Total Memory: 5.79GiB
 Name: docker-desktop
 ID: f09f6b80-da75-4873-a5c3-279333ee8c56
 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
 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

BC65E276-4B89-4452-BC30-3EB3777633B6/20240216112719

Additional Info

No response

[dgageot]

Sorry @tazle for breaking your workflow! I'm putting this kernel module back into Docker Desktop. We were missing a test to make sure this one isn't removed. The test is there, now. Hopefully, we can merge it for Docker Desktop 4.28.

[dgageot]

@tazle Could you give a try to Docker Desktop 4.28? It should be fixed

[tazle]

Seems to work, thank you!

[tiagonix]

Just a quick note... I also need this! =P

I initially tried to use picoceph with Docker Desktop for Mac (it works on Ubuntu with the docker.io Debian package) but it failed because there's no NBD (Network Block Device) available in the Docker Desktop Linux Kernel within its little VM.

Then, I changed picoceph to use loopback devices instead, but it also failed during lvcreate step due to the lack of /dev/mapper/control. But at least it went further!

Reference: dpeckett/picoceph#1

[dgageot]

@tiagonix thanks for the feedback. That's strange because CONFIG_BLK_DEV_NBD is indeed set to y in our kernel. So, the nbd should be there

[dgageot]

@tiagonix the source code is running cmd = exec.CommandContext(ctx, "/sbin/modprobe", "nbd") in a container that runs with docker run --rm ghcr.io/bucket-sailor/picoceph:latest

This won't work for multiple reasons:

• The container doesn't have the permission to load a module
• The container doesn't have /lib/modules/6.6.16-linuxkit folder mounted
• The module you're trying to load is built-in. It can't be loaded on demand

I'm pretty sure that removing the /sbin/modprobe nbd will work out of the box.

I'm going to close this issue because the original problem is fixed with 4.28. Feel free to open another issue and to ping me if needed.

[tiagonix]

@dgageot thank you for this information! I'll revisit the NBD approach. Cheers!