dvc[ssh] generate weird error with Poetry env manager.

[lambda-science]

Bug Report

dvc[ssh] can't be added to a project using Poetry env manager.

Description

When I create my package environnement using Poetry adding dvc with [ssh] extra create a weird unrelated error.
(This issue is crossposted on Poetry git here python-poetry/poetry#4683 ).

Reproduce

Minimal failing example:

1. poetry init
2. poetry add dvc[ssh]
3. poetry install

Full reproductibilty: get the pyproject.toml at the bottom, get an python installation with poetry installed and simply run poetry install with the file in the working directory.

Expected

Package dvc[ssh] should install fine with no error message.

Environment information

Output of dvc doctor:
As it workd with dvc alone (without the [ssh] extra, here is

$ dvc doctor

DVC version: 2.8.2 (pip)

Platform: Python 3.9.5 on Linux-5.10.16.3-microsoft-standard-WSL2-x86_64-with-glibc2.31
Supports:
webhdfs (fsspec = 2021.10.1),
http (aiohttp = 3.7.4.post0, aiohttp-retry = 2.4.6),
https (aiohttp = 3.7.4.post0, aiohttp-retry = 2.4.6)
Cache types: hardlink, symlink
Cache directory: ext4 on /dev/sdb
Caches: local
Remotes: ssh, local
Workspace directory: ext4 on /dev/sdb
Repo: dvc, git

Additional Information (if any):
For full reproductibility here is my pyproject.toml https://pastebin.com/avWt6UNk
Here is my full error log from poetry https://pastebin.com/MBveHXbW

I have the weird feeling that this issue is due to the fact that you need to first install dvc package and THEN dvc[ssh] (bcrypt looks missing). But that's not possible with Poetry, I can't have two line called "dvc" (one vanialla, one with the extra) and I can't have a line starting with dvc[ssh]
By removing the dvc with extras line from .toml file and doing poetry add dvc it works, but I can't use ssh plugin. Doing poetry add dvc[ssh] fails with the erros in the previous pastebin log.

KeyError

  Package('bcrypt', '3.2.0')

  at ~/miniconda3/lib/python3.9/site-packages/poetry/puzzle/solver.py:270 in _solve

while bcrypt is not in my .toml.

[efiop]

CC @isidentical , just in case you ran into it before with sshfs

[isidentical]

ssh extra depends on sshfs[bcrypt] which depends on asyncssh[bcrypt] which depends on bcrypt. So bcrypt is an indirect dependency of dvc[ssh].

[lambda-science]

ssh extra depends on sshfs[bcrypt] which depends on asyncssh[bcrypt] which depends on bcrypt. So bcrypt is an indirect dependency of dvc[ssh].

Yep, you are right, looking at the logs with a friend: it has to do with bcrypt that is called by asyncssh

EDIT: By using a fresh .toml file from poetry with only dvc[ssh] added, the same error arise.

[isidentical]

I'll see whether I can reproduce it / locate the cause.

[sjawhar]

I've run into this issue as well. I believe the bug is in Poetry's dependency resolver (I debugged it a bit). As a temporary workaround for the OP, you'll be able to lock your poetry venv if you add bcrypt as a dependency in pyproject.toml

[skshetry]

Fixed by #7171