Compose: On WSL, compose adds "\\?\C:" to the beginning of the context path

[marianatuma]

Description of the issue

I have posted about this on SO. Basically, I'm working on an older project that was previously in a Linux environment. I'm now using WSL (not WSL2), and docker is working fine. However, docker-compose adds \\?\C: to any path on the docker-compose.yml context, resulting in errors like:

...
OSError: [Errno 22] Invalid argument: '\\\\?\\C:\\Users\\tumadeathayde\\Documents\\Ubuntu\\GCES_2020\\gces-backend-2020\\venv\\bin\\python'

During handling of the above exception, another exception occurred:

...
OSError: Can not read file in context: \\?\C:\Users\tumadeathayde\Documents\Ubuntu\GCES_2020\gces-backend-2020\venv\bin\python

I have tried setting the flag COMPOSE_FORCE_WINDOWS_PATHS on and off, as well as COMPOSE_FORCE_WINDOWS_HOST also on and off. My Docker for Windows is using Linux containers right now, but I also tried switching to Windows containers with no success.

I have also tried different paths: releative, absolute, linux paths, windows paths, etc.

Context information (for bug reports)

Output of docker-compose version

docker-compose version 1.24.1, build 4667896b
docker-py version: 3.7.3
CPython version: 3.6.8
OpenSSL version: OpenSSL 1.0.2q  20 Nov 2018

Output of docker version

Client: Docker Engine - Community
 Version:           19.03.4
 API version:       1.40
 Go version:        go1.12.10
 Git commit:        9013bf583a
 Built:             Fri Oct 18 15:54:09 2019
 OS/Arch:           linux/amd64
 Experimental:      false

Server: Docker Engine - Community
 Engine:
  Version:          19.03.5
  API version:      1.40 (minimum version 1.12)
  Go version:       go1.12.12
  Git commit:       633a0ea
  Built:            Wed Nov 13 07:29:19 2019
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          v1.2.10
  GitCommit:        b34a5c8af56e510852c35414db4c1f4fa6172339
 runc:
  Version:          1.0.0-rc8+dev
  GitCommit:        3e425f80a8c931f88e6d94a8c831b9d5aa481657
 docker-init:
  Version:          0.18.0
  GitCommit:        fec3683

Output of docker-compose config
(Make sure to add the relevant -f and other flags)

services:
  api:
    build:
      context: C:\Users\tumadeathayde\Documents\Ubuntu\GCES_2020\gces-backend-2020
      dockerfile: ./etc/docker/Dockerfile
    container_name: api
    depends_on:
    - db
    environment:
      PRODUCTION: "false"
    ports:
    - 8000:8000/tcp
    restart: always
    volumes:
    - /c/Users/tumadeathayde/Documents/Ubuntu/GCES_2020/gces-backend-2020/etc:/etc/gces/:rw
    - /home/mariana/gces/logs:/srv/logs/:rw
    - /home/mariana/gces/media:/srv/media/:rw
    - /home/mariana/gces/static:/srv/static/:rw
    - /c/Users/tumadeathayde/Documents/Ubuntu/GCES_2020/gces-backend-2020/gces:/var/www/gces/:rw
  db:
    command:
    - mysqld
    - --character-set-server=utf8mb4
    - --collation-server=utf8mb4_unicode_ci
    container_name: db
    environment:
      MYSQL_DATABASE: gces_db
      MYSQL_PASSWORD: 0293rh3o4g0831hg
      MYSQL_ROOT_PASSWORD: a298g3h4h031304
      MYSQL_USER: gces_user
    image: mysql:5.7
    ports:
    - 3336:3306/tcp
    restart: always
    volumes:
    - /home/mariana/gces/mysql:/var/lib/mysql:rw
version: '3.0'

Steps to reproduce the issue

I'm not sure how reproduceable this issue is. I have seen many people have problems with docker-compose looking for /mnt/c, which is solved by mounting /c there. For me, the following steps cause the issue

1. On WSL, createa docker-compose.yml with any path in the context
2. docker-compose.exe -f <file path> up build
3. Errors listed above are thrown

Observed result

Docker-compose appends \\?\C: to the beginning of any path described in the context.

Expected result

Docker-compose uses path described in the context as-is, with no additions.

Stacktrace / full error message

Traceback (most recent call last):
  File "site-packages\docker\utils\build.py", line 96, in create_archive
OSError: [Errno 22] Invalid argument: '\\\\?\\C:\\Users\\tumadeathayde\\Documents\\Ubuntu\\GCES_2020\\gces-backend-2020\\venv\\bin\\python'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "docker-compose", line 6, in <module>
  File "compose\cli\main.py", line 71, in main
  File "compose\cli\main.py", line 127, in perform_command
  File "compose\cli\main.py", line 1085, in up
  File "compose\cli\main.py", line 1081, in up
  File "compose\project.py", line 527, in up
  File "compose\service.py", line 344, in ensure_image_exists
  File "compose\service.py", line 1084, in build
  File "site-packages\docker\api\build.py", line 159, in build
  File "site-packages\docker\utils\build.py", line 31, in tar
  File "site-packages\docker\utils\build.py", line 100, in create_archive
OSError: Can not read file in context: \\?\C:\Users\tumadeathayde\Documents\Ubuntu\GCES_2020\gces-backend-2020\venv\bin\python
[18416] Failed to execute script docker-compose

Additional information

OS: Windows 10, build 18363.0
WSL: Linux 4.4.0-18362-Microsoft #476-Microsoft Fri Nov 01 16:53:00 PST 2019 x86_64 x86_64 x86_64 GNU/Linux

If there is any information missing, please let me know and I'll add it. I'm not well versed in Docker or WSL.

[marianatuma]

If anyone runs into this error: Apparently by calling docker-compose I was calling Docker for Windows' docker compose, which uses windows' python. Python's sys.platform is 'win32' (of course), and that was causing docker compose to add that prefix to my context. WSL's docker-compose calls the correct python, which returns sys.platform as linux.

[spmartin]

How can I fix this?