Compose: pyrsistent 0.17.0 breaks python2 support

[stas-sbi]

Description of the issue

docker_compose python module doesn't work in python2 anymore

Context information (for bug reports)

not relevant

Output of docker-compose version

not relevant

Output of docker version

not relevant

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

not relevant

Steps to reproduce the issue

1. pip install docker-compose
2. Try to use ansible module docker_compose

Observed result

fails on command

Expected result

should not fail

Stacktrace / full error message

    /usr/local/lib/python2.7/dist-packages/paramiko/transport.py:33: CryptographyDeprecationWarning: Python 2 is no longer supported by the Python core team. Support for it is now deprecated in cryptography, and will be removed in a future release.
      from cryptography.hazmat.backends import default_backend
    Traceback (most recent call last):
      File "<stdin>", line 102, in <module>
      File "<stdin>", line 94, in _ansiballz_main
      File "<stdin>", line 40, in invoke_module
      File "/usr/lib/python2.7/runpy.py", line 188, in run_module
        fname, loader, pkg_name)
      File "/usr/lib/python2.7/runpy.py", line 82, in _run_module_code
        mod_name, mod_fname, mod_loader, pkg_name)
      File "/usr/lib/python2.7/runpy.py", line 72, in _run_code
        exec code in run_globals
      File "/tmp/ansible_docker_compose_payload_eqkS_O/ansible_docker_compose_payload.zip/ansible/modules/cloud/docker/docker_compose.py", line 483, in <module>
      File "/usr/local/lib/python2.7/dist-packages/compose/cli/command.py", line 11, in <module>
        from .. import config
      File "/usr/local/lib/python2.7/dist-packages/compose/config/__init__.py", line 6, in <module>
        from .config import ConfigurationError
      File "/usr/local/lib/python2.7/dist-packages/compose/config/config.py", line 51, in <module>
        from .validation import match_named_volumes
      File "/usr/local/lib/python2.7/dist-packages/compose/config/validation.py", line 12, in <module>
        from jsonschema import Draft4Validator
      File "/usr/local/lib/python2.7/dist-packages/jsonschema/__init__.py", line 21, in <module>
        from jsonschema._types import TypeChecker
      File "/usr/local/lib/python2.7/dist-packages/jsonschema/_types.py", line 3, in <module>
        from pyrsistent import pmap
      File "/usr/local/lib/python2.7/dist-packages/pyrsistent/__init__.py", line 3, in <module>
        from pyrsistent._pmap import pmap, m, PMap
      File "/usr/local/lib/python2.7/dist-packages/pyrsistent/_pmap.py", line 98
        ) from e
             ^
    SyntaxError: invalid syntax

Additional information

irrelevant

Possible solution: fix version of pyrsistent as 0.16.0 in requirements.txt

[aiordache]

Hi @stas-sbi. Thanks for raising the issue, I forgot to add to the release notes for 1.27.0 that we dropped support for Python2.7.

[felixfontein]

@aiordache it would be better to populate the python_requires field in setup.py to make PyPi / pip know about this as well. The best solution would be to release a new patch version which implements this and yank the 1.27.0 release, i.e. same as in tobgu/pyrsistent#205.

[aiordache]

@felixfontein the field is already set in setup.py https://github.com/docker/compose/blob/980ec85bf45b6dc34cd4f37bf7736832337e7fe1/setup.py#L92

[stas-sbi]

The issue though is that older versions of compose are also broken now. Can we have a minor bump of 1.26.x which with still works python2? This would give us some time to upgrade.

[ulyssessouza]

@stas-sbi I'm sorry, but I'm afraid that a minor bump on 1.26.x won't be the way to go.

Actually the support for python 2.x was dropped quite a long time ago (since January 1st) from Python's side.
We also had a banner in the README.md promising the drop for 1.26.x and we actually dropped in 1.27.x

[stas-sbi]

I see. Ubuntu supports python2 independently though until EOL of Ubuntu 18.04 if I recall correctly.

[stas-sbi]

I'll try to find a work around then.

[felixfontein]

@stas-sbi the easiest way around this is to provide a constraints file when running pip, which restricts the version of pyrsistent for Python 2.7 only. (If you use the same file with Python 3, you'll still get the latest version.)

[stas-sbi]

Apparently the latest incompatible version of pyrsistent was pushed to python2 repo. Not sure if they are going/can remove it. What I mean is that I try to install docker-compose using python2 I get 1.26.2 version of docker compose but 0.17.2 version of pyrsistent which cannot be installed.

[ulyssessouza]

As it's an indirect dependency, you can install a pinned version that supports py2 then try to install docker-compose

[stas-sbi]

Yes, this is what I did. Good enough for now. Thanks.

[ulyssessouza]

Thanks for the report @stas-sbi !

[ZILosoft]

same thing. any working solution?