Dependency on "decorator" package not captured in v3.0.x

[lrbison]

When installing fabric in a fresh venv, Connection cannot be imported:

pip install 'fabric<3.0.0'
python -c 'from fabric import Connection'

The above works. But starting with 3.0.0, (including the recent 3.0.1):

pip install 'fabric>=3.0.0'
python -c 'from fabric import Connection'
Traceback (most recent call last):
  File "/home/lrbison/venvC/lib64/python3.7/site-packages/fabric/connection.py", line 7, in <module>
    from invoke.vendor.decorator import decorator
ModuleNotFoundError: No module named 'invoke.vendor.decorator'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/lrbison/venvC/lib64/python3.7/site-packages/fabric/__init__.py", line 3, in <module>
    from .connection import Config, Connection
  File "/home/lrbison/venvC/lib64/python3.7/site-packages/fabric/connection.py", line 9, in <module>
    from decorator import decorator
ModuleNotFoundError: No module named 'decorator'

[nelsonq]

@lrbison Yep, I am getting this error as well.

Looks like It is due to the invoke dependency getting upgraded to 2.1.0 on April 28 which breaks the compatibility.

On version v2.1.0, It removed the https://github.com/pyinvoke/invoke/blob/2.0/invoke/vendor/decorator.py from v2.0.0

To workaround it, I have to downgrade the invoke to 2.0.0.

RUN pip install fabric invoke==2.0.0

I would assume it is a dependency compatibility issue of Fabric. Looking forward to an official fix.

[bitprophet]

Yup this is technically an Invoke level breakage, see pyinvoke/invoke#935 - however I think the correct fix is to make Fabric grow the dependency officially as it was sloppy hygiene to import it via Invoke's vendored copy. I'll commit the fix to master now and it will be out in 3.1 (since it's "sort of" adding a "new" dependency) which is in the works now. Thanks!

[exhuma]

Thank you @bitprophet for the quick response

edit: Do you have an expected release date for this? We have around 300 projects with daily builds and all of those using fabric exploded over the weekend because of this. Just to know whether we should start nudging in a fix or not to get our pipelines working again.

[bitprophet]

@exhuma There's nothing in Invoke 2.1 that you would be likely to care a lot about, so in your shoes I would definitely update whatever does your pip installing, to explicitly specify invoke<2.1 for the time being. I would expect Fabric 3.1 to be out within the next few weeks or so, at which point you could safely remove the invoke pin again.

[bitprophet]

Invocations 3.1 (no relation to Fabric 3.1...I just happened to get new major revs everywhere recently when dropping Python 2 😅) now out, and Fabric main branch now using it to prove this type of issue will be caught by our CI in the future: https://app.circleci.com/pipelines/github/fabric/fabric/191/workflows/8e7ddf2d-8d19-4579-a361-9c2a00e9f9c4/jobs/775

EDIT: and with the fix in place in Fabric's main branch (see autoclose link below), it passes again: https://app.circleci.com/pipelines/github/fabric/fabric/192/workflows/eb1bd2af-4478-4874-935a-dca384bc5258/jobs/793?invite=true#step-106-633

Look on PyPI for Fabric 3.1 to come out sometime hopefully later this month!

[Wedge009]

I confirm installing Fabric 3.1 picks up decorator as part of its dependency chain. Thanks.