[BUG] Bind mounts not working when using DOCKER_HOST variable for Windows Containers

[0xff8]

Description

I am trying to start windows containers using docker compose from linux host on remote windows machine using SSH. When I run docker compose up command , remote windows host fails to run containers, since the local current path gets prepended to the volume.

Error response from daemon: invalid mount config for type "bind": invalid mount path: '/builds/projects/windows-docker/C:\Users\test-user\results' mount path must be absolute

What I have tried so far:

• added platform: windows/amd64 to docker-compose.yaml
• added export DOCKER_DEFAULT_PLATFORM=windows/amd64
• Tried Unix-like path //C/Users//results (not working, although compose client stops adding current path to the volume name)
• Tried to add a slash in front of the path /C:\Users<YourUserName>\results (not working, remote windows machine complains that the path must be absolute)

Steps To Reproduce

1. Set DOCKER_HOST variable to ssh://user@windows-host/
2. From linux host run docker compose up
3. compose.yaml:

services:
  node:
    platform: windows/amd64
    image: ${IMAGE}
    volumes:
      - type: bind
        source: C:\Users\<YourUserName>\results
        target: C:\Results
    restart: unless-stopped
    stdin_open: true
    tty: true

Compose Version

Docker Compose version v2.35.0

Docker Environment

Server: Docker Engine - Community
 Engine:
  Version:          28.0.1
  API version:      1.48 (minimum version 1.24)
  Go version:       go1.23.6
  Git commit:       bbd0a17
  Built:            Wed Feb 26 10:40:47 2025
  OS/Arch:          windows/amd64
  Experimental:     false

Anything else?

If possible - suggest some hack / other method

[fabiang]

Yes this is a regression which was probably introduced with #12725. Also Named Pipe mounts do not work as before:

validating docker-compose.yml: services.node.volumes.1.type services.node.volumes.1.type must be one of the following: "bind", "volume", "tmpfs", "cluster", "image"

My Compose file:

services:
  node:
    image: jenkins/inbound-agent:${AGENT_VERSION_WINDOWS:-windowsservercore-ltsc2022}
    volumes:
      - type: npipe
        source: '\\.\pipe\docker_engine'
        target: '\\.\pipe\docker_engine'

I downgraded to Docker Compose version v2.31.0 (last stable Alpine version) and it's working again (previously I had the packages from "edge" installed).

[perosb]

Same here with npipe.
2.35.0 breaks npipe which works fine in 2.34.0

[ndeloof]

named pipe support has been restored by compose-spec/compose-go#771

original issue is that compose doesn't guess a Windows source path is absolute when running on Linux. This is a pretty uncommon scenario, actually codebase tries to detect the opposite: target unix absolute path when running on Windows, which is a common case (Docker Desktop Windows), see https://github.com/compose-spec/compose-go/blob/ca961cc58145b2b1b8221f2a0c4e9734772156fc/paths/unix.go#L26

[0xff8]

Hi @ndeloof ,

Thanks for the help!
Do you think instead of guessing, it is possible to rely on platform: field inside of the service description? This seems very logical to me. If a user explicitly defines the platform as windows/amd64 , then windows path can be expected, and if it is not windows - then there is no need to check for windows paths.