Move to Python 3: dependencies status

[arikfr]

Thanks to the work of @cclauss our code is (more) ready for Python 3. I also ran caniusepython3 on our requirements files and the results are very encouraging:

$ caniusepython3 --requirements requirements.txt
Finding and checking dependencies ...

You need 5 projects to transition to Python 3.
Of those 5 projects, 4 have no direct dependencies blocking their transition:

  chromelogger
  flask-sslify
  python-geoip (which is blocking python-geoip-geolite2)
  restrictedpython

• python-geoip has a Python 3 compatible alternative (python-geoip-python3)
• Latest master version of flask-sslify is marked as Python 3 compatible, but no new version was released for a long time.
• chromelogger is unknown but we can either drop it or update to support Python 3 (~140 lines of code).
• restrictedpython has an unreleased version 4 that supports Python 3.

$ caniusepython3 --requirements requirements_all_ds.txt
Finding and checking dependencies ...

You need 1 project to transition to Python 3.
Of that 1 project, 1 has no direct dependencies blocking its transition:

  pyhive

I'm not sure why pyhive is marked as not supported, because it is. Maybe we just need to update the version.

$ caniusepython3 --requirements requirements_dev.txt
Finding and checking dependencies ...

You need 1 project to transition to Python 3.
Of that 1 project, 1 has no direct dependencies blocking its transition:

  pytest-watch

I'm not sure about the state of pytest-watch, but we can always remove it.

[cclauss]

PyHive has no trove classifiers in its PyPI record... https://pypi.org/project/PyHive

But it is being tested under all current versions of CPython https://github.com/dropbox/PyHive/blob/master/.travis.yml#L8

dropbox/PyHive#243

[cclauss]

Same with pytest-watch... https://pypi.org/project/pytest-watch

joeyespo/pytest-watch#95

[jezdez]

This is super exciting, didn't realize how close we'd be in terms of dependencies.

For flask-sslify I planned to work on mozilla#562 and port Redash to use flask-talisman which also supports enforcing encrypted connections (on top of plenty of other security related things, which is what interests us at Mozilla). A bit like a kill two birds with one stone situation. Any general objections about this?

[arikfr]

@jezdez sounds good to me. 👍

[truebit]

I saw many ImportError when trying to run on python3.
Is there any issue to locate those incompatible codes for Python3?

[jezdez]

@arikfr Oh btw, we merged flask-talisman! Which means there shouldn't be any blocker to this?

[arikfr]

@jezdez We should probably run caniusepython3 again to review if anything changed.

But there are probably other things that are blocking switching over to Python 3 in our code or dependencies. I'm just not sure what they are. 😳

[jezdez]

$ caniusepython3 -r requirements.txt
Finding and checking dependencies ...

You need 3 projects to transition to Python 3.
Of those 3 projects, 2 have no direct dependencies blocking their transition:

  chromelogger
  python-geoip (which is blocking python-geoip-geolite2)

$ caniusepython3 -r requirements_all_ds.txt
Finding and checking dependencies ...

You need 3 projects to transition to Python 3.
Of those 3 projects, 3 have no direct dependencies blocking their transition:

  ibm-db
  pydruid
  pyhive

$ caniusepython3 -r requirements_dev.txt
Finding and checking dependencies ...

🎉  You have 0 projects blocking you from using Python 3!

[arikfr]

The requirements.txt check says 3 projects, but lists 2. Any idea why?

[jezdez]

I think it counts python-geoip-geolite2 and python-geoip individually:

caniusepython3 -p python-geoip-geolite2
Finding and checking dependencies ...

You need 2 projects to transition to Python 3.
Of those 2 projects, 1 has no direct dependencies blocking its transition:

  python-geoip (which is blocking python-geoip-geolite2)

[jezdez]

IBM-db is tested under Py2 and Py3 https://github.com/ibmdb/python-ibmdb/blob/master/.travis.yml

I've opened ibmdb/python-ibmdb#395 to fix caniusepython3 missing this.

[arikfr]

pydruid is also tested with Python 3.6: https://github.com/druid-io/pydruid/blob/master/.travis.yml

[arikfr]

Based on this, it looks like the dependencies are probably a non issue. Now there is only the small issue of figuring out if our code works as intended on Python 3 😅

[cclauss]

My sense is that you should try putting apt install python3 python3-pip into your CirceCI builds and see where the tests fail. I think you are really close and it would be good to understand what is failing.

[jezdez]

pydruid is also tested with Python 3.6: druid-io/pydruid:.travis.yml@master

Opened druid-io/pydruid#164

[jezdez]

Yeah, running 2to3 (or some wrappers mentioned on https://docs.python.org/3/howto/pyporting.html) make sense as well.

There is a pretty good high-level overview in The Conservative Python 3 Porting Guide which I think applies to Redash well.

[cclauss]

I would avoid 2to3 because it tends to break Py2 compatibility to get to Py3 compatibility.

I would recommend using either futurize or modernize instead. These thin wrappers on top of 2to3 that preserve compatibility with bothPy2 and Py3

[arikfr]

I'm not sure we will support Python 2 once we move to 3.

[cclauss]

Your call. However best practice is to run them both in a single codebase for at least a little time because the A/B testing can be invaluable. See the conservative guild and python docs on porting.

[cclauss]

A few Python 3 issues to watch out for in the porting...

flake8 testing of https://github.com/getredash/redash on Python 3.7.1

$ flake8 . --count --select=E9,F63,F72,F82 --show-source --statistics

./redash/query_runner/__init__.py:290:8: F821 undefined name 'unicode'
    if unicode(string_value).lower() in ('true', 'false'):
       ^
./redash/query_runner/drill.py:29:16: F821 undefined name 'unicode'
        return unicode(string_value).lower() == 'true'
               ^
./redash/query_runner/drill.py:34:12: F821 undefined name 'unicode'
    return unicode(string_value)
           ^
./redash/models/parameterized_query.py:16:48: F821 undefined name 'unicode'
    return {"name": row[name_column], "value": unicode(row[value_column])}
                                               ^
./redash/models/parameterized_query.py:122:53: F821 undefined name 'basestring'
            "text": lambda value: isinstance(value, basestring),
                                                    ^
./redash/models/parameterized_query.py:125:36: F821 undefined name 'unicode'
            "query": lambda value: unicode(value) in [v["value"] for v in dropdown_values(definition["queryId"])],
                                   ^
./redash/utils/__init__.py:99:28: F821 undefined name 'buffer'
        elif isinstance(o, buffer):
                           ^
./redash/authentication/saml_auth.py:116:12: F632 use ==/!= to compare str, bytes, and int literals
        if key is 'Location':
           ^
./tests/test_utils.py:47:37: F821 undefined name 'buffer'
        self.assertEqual(json_dumps(buffer("test")), '"74657374"')
                                    ^
1     F632 use ==/!= to compare str, bytes, and int literals
8     F821 undefined name 'unicode'
9

[arikfr]

I setup a new CircleCI job to run tests on Python 3. It uncovered that our MySQL lib does not support Python 3:

https://circleci.com/gh/getredash/redash/21775

I updated to mysqlclient and waiting for a new build:

https://circleci.com/gh/getredash/redash/21782

--

Update: new build fails too. I will iterate on the dependencies locally.

[cclauss]

See the comments at the bottom of mitsuhiko/python-geoip#5

[arikfr]

Python 2 support after Python 3: I guess it depends on how much effort it will require. If possible we will keep support for both.

Flake 8 tests: I assumed that the CircleCI job for Flake8 tests on Python 3 will fail if it doesn't pass 😳 Oops.

[cclauss]

https://stackoverflow.com/questions/4960048/how-can-i-connect-to-mysql-in-python-3-on-windows

[arikfr]

There are a few more dependencies that fail to build with the Python 3 image.

I noticed caniusepython3 maintains a list of projects that have Python 3 alternatives, like mysql-python -> mysqlclient. It could be nice if it mentioned this in the output...

Update: it has a verbose output that should list them -- will check.

[jezdez]

Regarding whether to go 2/3 or straight to 3, I don't think it matters which strategy to use as long as we can run on Python 3 before the end of the year -- so chose the strategy that works best for you.

FWIW I know a few distributors will support Python 2 going forward, but it'd cost us, which I don't think is a viable option either for Redash SaaS or the OSS users. TBH I fully expect to see Python 2 vulnerabilities to show up after the EOL.

Handy tool: https://pythonclock.org/

[arikfr]

This is not related to the issue, but I assume that the issue author or followers might have SAML enabled for their deployment and should be aware of the following Security Advisory: #5961. This affects all Redash versions and should be patched immediately.