Installation fails on python 2.7

[ccancellieri]

Hi I'm installing a fresh copy of this plugin over my docker instance and I'm getting:

...
Adding ckanext-scheming 2.1.0 to easy-install.pth file

Installed /srv/app/src_extensions/ckanext-scheming
Processing dependencies for ckanext-scheming==2.1.0
Searching for pyyaml
Reading https://pypi.org/simple/pyyaml/
Downloading https://files.pythonhosted.org/packages/36/2b/61d51a2c4f25ef062ae3f74576b01638bebad5e045f747ff12643df63844/PyYAML-6.0.tar.gz#sha256=68fb519c14306fec9720a2a5b45bc9f0c8d1b9c72adf45c37baedfcd949c35a2
Best match: PyYAML 6.0
Processing PyYAML-6.0.tar.gz
Writing /tmp/easy_install-hdquDQ/PyYAML-6.0/setup.cfg
Running PyYAML-6.0/setup.py -q bdist_egg --dist-dir /tmp/easy_install-hdquDQ/PyYAML-6.0/egg-dist-tmp-lli1fC
Traceback (most recent call last):
  File "/srv/app/src_extensions/ckanext-scheming/setup.py", line 43, in <module>
    """,
  File "/usr/lib/python2.7/site-packages/setuptools/__init__.py", line 162, in setup
    return distutils.core.setup(**attrs)
  File "/usr/lib/python2.7/distutils/core.py", line 151, in setup
    dist.run_commands()
  File "/usr/lib/python2.7/distutils/dist.py", line 953, in run_commands
    self.run_command(cmd)
  File "/usr/lib/python2.7/distutils/dist.py", line 972, in run_command
    cmd_obj.run()
  File "/usr/lib/python2.7/site-packages/setuptools/command/develop.py", line 38, in run
    self.install_for_development()
  File "/usr/lib/python2.7/site-packages/setuptools/command/develop.py", line 156, in install_for_development
    self.process_distribution(None, self.dist, not self.no_deps)
  File "/usr/lib/python2.7/site-packages/setuptools/command/easy_install.py", line 758, in process_distribution
    [requirement], self.local_index, self.easy_install
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 782, in resolve
    replace_conflicting=replace_conflicting
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 1065, in best_match
    return self.obtain(req, installer)
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 1077, in obtain
    return installer(requirement)
  File "/usr/lib/python2.7/site-packages/setuptools/command/easy_install.py", line 685, in easy_install
    return self.install_item(spec, dist.location, tmpdir, deps)
  File "/usr/lib/python2.7/site-packages/setuptools/command/easy_install.py", line 711, in install_item
    dists = self.install_eggs(spec, download, tmpdir)
  File "/usr/lib/python2.7/site-packages/setuptools/command/easy_install.py", line 896, in install_eggs
    return self.build_and_install(setup_script, setup_base)
  File "/usr/lib/python2.7/site-packages/setuptools/command/easy_install.py", line 1164, in build_and_install
    self.run_setup(setup_script, setup_base, args)
  File "/usr/lib/python2.7/site-packages/setuptools/command/easy_install.py", line 1150, in run_setup
    run_setup(setup_script, args)
  File "/usr/lib/python2.7/site-packages/setuptools/sandbox.py", line 253, in run_setup
    raise
  File "/usr/lib/python2.7/contextlib.py", line 35, in __exit__
    self.gen.throw(type, value, traceback)
  File "/usr/lib/python2.7/site-packages/setuptools/sandbox.py", line 195, in setup_context
    yield
  File "/usr/lib/python2.7/contextlib.py", line 35, in __exit__
    self.gen.throw(type, value, traceback)
  File "/usr/lib/python2.7/site-packages/setuptools/sandbox.py", line 166, in save_modules
    saved_exc.resume()
  File "/usr/lib/python2.7/site-packages/setuptools/sandbox.py", line 141, in resume
    six.reraise(type, exc, self._tb)
  File "/usr/lib/python2.7/site-packages/setuptools/sandbox.py", line 154, in save_modules
    yield saved
  File "/usr/lib/python2.7/site-packages/setuptools/sandbox.py", line 195, in setup_context
    yield
  File "/usr/lib/python2.7/site-packages/setuptools/sandbox.py", line 250, in run_setup
    _execfile(setup_script, ns)
  File "/usr/lib/python2.7/site-packages/setuptools/sandbox.py", line 45, in _execfile
    exec(code, globals, locals)
  File "/tmp/easy_install-hdquDQ/PyYAML-6.0/setup.py", line 67, in <module>

This is due to this:
yaml/pyyaml#476

Probably we can enforce the correct version (5.4) here to fix

ckanext-scheming/setup.py

Line 28 in a5b5522

'pyyaml',

[ccancellieri]

Note: I'm also getting:

Requirement already satisfied: python-slugify>=1.0 in /usr/lib/python2.7/site-packages/python_slugify-5.0.2-py2.7.egg (from ckanapi->ckanext-scheming==2.1.0) (5.0.2)
ERROR: Package 'python-slugify' requires a different Python: 2.7.18 not in '>=3.6'

That could be solved with:

pip install python-slugify==4.0.1

But I'm not sure from which package/plugin it comes (already provided), could it be the core?

[ccancellieri]

I also had to do

install_requires=[
-        'pyyaml',
+        'pyyaml==5.4',

[ccancellieri]

I think we can set
pyyaml<=5.4