ImportError when using CommonMark-py with Google App Engine

[badersur]

When I try to use CommonMark-py -which uses python-future- with App Engine I get this error, if I put import CommonMark at the top:

ERROR    2016-08-26 14:04:59,126 wsgi.py:263] 
Traceback (most recent call last):
  File "/home/super/google_appengine/google/appengine/runtime/wsgi.py", line 240, in Handle
    handler = _config_handle.add_wsgi_middleware(self._LoadHandler())
  File "/home/super/google_appengine/google/appengine/runtime/wsgi.py", line 299, in _LoadHandler
    handler, path, err = LoadObject(self._handler)
  File "/home/super/google_appengine/google/appengine/runtime/wsgi.py", line 85, in LoadObject
    obj = __import__(path[0])
  File "/home/super/WebProjects/myapp/blog.py", line 3, in <module>
    from models import Post
  File "/home/super/WebProjects/myapp/models.py", line 1, in <module>
    import CommonMark
  File "/home/super/WebProjects/myapp/libs/CommonMark/__init__.py", line 4, in <module>
    from CommonMark.main import commonmark
  File "/home/super/WebProjects/myapp/libs/CommonMark/main.py", line 15, in <module>
    from CommonMark.dump import dumpAST, dumpJSON
  File "/home/super/WebProjects/myapp/libs/CommonMark/dump.py", line 3, in <module>
    from builtins import str
  File "/home/super/WebProjects/myapp/libs/builtins/__init__.py", line 8, in <module>
    from future.builtins import *
  File "/home/super/WebProjects/myapp/libs/future/builtins/__init__.py", line 10, in <module>
    from future.builtins.iterators import (filter, map, zip)
  File "/home/super/WebProjects/myapp/libs/future/builtins/iterators.py", line 43, in <module>
    from future.types import newrange as range
  File "/home/super/WebProjects/myapp/libs/future/types/__init__.py", line 243, in <module>
    from .newrange import newrange
  File "/home/super/WebProjects/myapp/libs/future/types/newrange.py", line 25, in <module>
    from future.backports.misc import count   # with step parameter on Py2.6
  File "/home/super/WebProjects/myapp/libs/future/backports/__init__.py", line 17, in <module>
    from .misc import (ceil,
  File "/home/super/WebProjects/myapp/libs/future/backports/misc.py", line 900, in <module>
    from subprocess import check_output
ImportError: cannot import name check_output
INFO     2016-08-26 14:04:59,140 module.py:788] default: "GET /blog/5822463824887808 HTTP/1.1" 500 -
INFO     2016-08-26 14:04:59,196 module.py:788] default: "GET /favicon.ico HTTP/1.1" 304 -

But, when I import CommonMark inside a method I get:

ERROR    2016-08-26 13:38:08,116 webapp2.py:1552] cannot import name check_output
Traceback (most recent call last):
  File "/home/super/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 1535, in __call__
    rv = self.handle_exception(request, response, e)
  File "/home/super/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 1529, in __call__
    rv = self.router.dispatch(request, response)
  File "/home/super/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 1278, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/home/super/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 1102, in __call__
    return handler.dispatch()
  File "/home/super/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 572, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/home/super/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 570, in dispatch
    return method(*args, **kwargs)
  File "/home/super/WebProjects/myapp/blog.py", line 29, in get
    self.render('permalink.html', post=post, url=self.url)
  File "/home/super/WebProjects/myapp/handlers.py", line 33, in render
    self.write(self.render_str(template, **kw))
  File "/home/super/WebProjects/myapp/handlers.py", line 30, in render_str
    return render_str(template, **kw)
  File "/home/super/WebProjects/myapp/handlers.py", line 20, in render_str
    return t.render(kw)
  File "/home/super/google_appengine/lib/jinja2-2.6/jinja2/environment.py", line 894, in render
    return self.environment.handle_exception(exc_info, True)
  File "/home/super/WebProjects/myapp/templates/permalink.html", line 1, in top-level template code
    {% extends "base.html" %}
ImportError: cannot import name check_output
INFO     2016-08-26 13:38:08,186 module.py:788] default: "GET /blog/5822463824887808 HTTP/1.1" 500 228
INFO     2016-08-26 13:38:08,281 module.py:788] default: "GET /favicon.ico HTTP/1.1" 304 -

I am used to add other libraries to my App Engine projects as described in App Engine's installing a library document but this library causes these errors even though it is working with webapp2 outside App Engine!

I reported this issue to CommonMark but Mr. @nikolas suggested reporting it here.

Note: I am using App Engine Standard Environment and Python 2.7.12. Also, It seems like App Engine is using version 2.7.2.

[QuLogic]

GAE has a patched subprocess that disables running anything; I guess future will have to ignore the import error unless really needed.

[badersur]

Thank you @QuLogic for your explanation. It seems I have to look for other Markdown library until this issue is fixed!

[nikolas]

@badersur CommonMark-py only started requiring the future module in version 0.6.2 - see the changelog: https://github.com/rtfd/CommonMark-py/blob/master/CHANGELOG.md#062-2016-01-08

So, a temporary solution could be to use CommonMark version 0.6.1, until the issue is resolved in future.

[badersur]

Thank you @nikolas for telling me about this release.

I tested it and it worked nicely except for producing non HTML5 tags (hr, br and img)! On the other hand, it didn't wrap iframe with p tag like an other library!

[nikolas]

I'm not sure what you mean - these tags are in the HTML5 spec:

• https://www.w3.org/TR/html-markup/hr.html
• https://www.w3.org/TR/html-markup/br.html
• https://www.w3.org/TR/html-markup/img.html

But in any case, if you have an issue with this html representation, that's not CommonMark-py's decision, but the CommonMark spec itself: http://spec.commonmark.org/ So any suggestions there you can bring up in the commonmark forums.

[badersur]

Sorry. I meant the library produces <br />, <hr /> and <img /> instead of <br>... without the trailing /.

BTW, I included your comments on an answer to my question on Quora: How can I use CommonMark-py on Google App Engine.

[nikolas]

Ah okay, well that is as defined in the commonmark spec: http://spec.commonmark.org/0.26/#example-599

If you think this should be changed you can open an issue here: https://github.com/jgm/CommonMark/issues or open a discussion here: https://talk.commonmark.org/c/spec

[badersur]

My bad! I thought because it is a specification then it will be generating proper HTML5 tags! Maybe I should read the lengthy document 😓

[edschofield]

This should be fixed now with future v0.16.0. Please try this again on GAE and re-open this issue if you encounter any more problems.

[badersur]

Thank you @edschofield for fixing this issue. It's working now 👍 :)