Incompatibility of python 3.10 and elasticsearch 7.10 with Haystack 1.5

[julian-risch]

Describe the bug
The new Haystack v1.5.0 release supports python 3.10. However, I came across an incompatibility issue/a small bug in the elasticsearch client 7.10 and python 3.10.

The error message is as follows when running python tutorials/Tutorial1_Basic_QA_Pipeline.py:

INFO - haystack.document_stores.base -  Numba not found, replacing njit() with no-op implementation. Enable it with 'pip install numba'.
Traceback (most recent call last):
  File "/opt/homebrew/Caskroom/miniforge/base/envs/py310_v150/lib/python3.10/site-packages/elasticsearch/compat.py", line 36, in <module>
    from collections.abs import Mapping
ModuleNotFoundError: No module named 'collections.abs'

So there is a typo collections.abs instead of collections.abc in the elasticsearch client, which lets the import fail.

It was fixed here:
elastic/elasticsearch-py@cf39af3

Downgrading the elasticsearch client to 7.9 worked for me. Maybe we should upgrade the client in the setup config (7.10 is currently the upper limit)? Another option would be to exclude version 7.10 for now but so far not many people seem to be using Haystack with python 3.10. What are your thoughts?

[masci]

v7.10.1 contains the fix you mention, I'd just adjust our setup.cfg to include that too with elasticsearch>=7.7,<7.11

[moravveji]

As a quick workaround, I just installed a conda environment with a base Python 3.9 (instead of 3.10), and then I could successfully import haystack, without the ImportError.