Make psycopg2-binary satisfy installation requirements

[Ryan J Ollos]

I've been getting this warning:

/Users/rjollos/Documents/Workspace/trac-dev/pve/lib/python2.7/site-packages/psycopg2/__init__.py:144:
UserWarning: The psycopg2 wheel package will be renamed from release 2.8;
in order to keep installing from binary please use "pip install psycopg2-binary" instead.
For details see: <http://initd.org/psycopg/docs/install.html#binary-install-from-pypi>.

On installing psycopg2-binary, the module postgres_backend module is skipped because the installation requirement isn't satisfied.

I think we went down a similar path when supporting the MySQL library dependencies and couldn't find a way to write the equivalent of psycopg2 or psycopg-binary as the installation requirement​.

$pip list --format=columns | grep psycopg2
psycopg2        2.7.4
psycopg2-binary 2.7.4

I haven't researched potential solutions yet.

[Jun Omae]

After the patch (PoC):

1. DistributionNotFound is raised if psycopg2 module is not available.

   18:05:07 Trac[loader] DEBUG: Loading plugin "trac.db.postgres" from "/dev/shm/venv/lib/python2.7/site-packages"
   18:05:07 Trac[loader] DEBUG: Skipping "trac.db.postgres = trac.db.postgres_backend": DistributionNotFound: The 'psycopg2>=2.0 or psycopg2-binary>=2.0' distribution was not found and is required by Trac
   

2. pip install Trac[psycopg2] leads installing Trac and psycopg2.
3. pip install Trac[psycopg2-binary] leads installing Trac and psycopg2-binary.

setup.py

@@ -99 +99 @@
         'babel': ['Babel>=0.9.5'],
         'mysql': ['MySQL-python >= 1.2.2'],
         'postgresql': ['psycopg2 >= 2.0'],
+        'psycopg2': ['psycopg2 >= 2.0'],
+        'psycopg2-binary': ['psycopg2-binary'],
         'pygments': ['Pygments>=0.6'],
         'rest': ['docutils>=0.3.9'],
         'textile': ['textile>=2.0'],
@@ -115 +117 @@
         trac.admin.web_ui = trac.admin.web_ui
         trac.attachment = trac.attachment
         trac.db.mysql = trac.db.mysql_backend[mysql]
-        trac.db.postgres = trac.db.postgres_backend[postgresql]
+        trac.db.postgres = trac.db.postgres_backend
         trac.db.sqlite = trac.db.sqlite_backend
         trac.mimeview.patch = trac.mimeview.patch
         trac.mimeview.pygments = trac.mimeview.pygments[pygments]

trac/db/postgres_backend.py

@@ -14 +14 @@
 #
 # Author: Christopher Lenz <cmlenz@gmx.de>
 
+from pkg_resources import DistributionNotFound
 import os
 import re
 
@@ -37 +38 @@
     from psycopg2.extensions import register_type, UNICODE, \
                                     register_adapter, AsIs, QuotedString
 except ImportError:
-    has_psycopg = False
-    psycopg2_version = None
+    raise DistributionNotFound('psycopg2>=2.0 or psycopg2-binary', ['Trac'])
 else:
     has_psycopg = True
     register_type(UNICODE)

[Ryan J Ollos]

I'm reviewing your patch and see now that the issue only affects 1.2-stable (#12096).

[Ryan J Ollos]

Changes look good to me. I added a little cleanup on this branch: log:rjollos.git:t12989_psycopg2_binary.

I've never considered specifying extras while installing Trac. That's a good feature.

[Ryan J Ollos]

Committed to 1.2-stable in r16572, but reverted in [16573:16574]. Sorry, I was careless with the commits.

[Ryan J Ollos]

[5826f28ee/rjollos.git] would import the necessary backend, depending on the dburi. Needs to be exercised a bit more for different test execution scenarios. On trunk we can use ​importlib rather than __import__.

[Ryan J Ollos]

When psycopg2 or psycopg2-binary is not installed, running the tests results in:

$ make db=postgres test

Python: /Users/rjollos/.pyenv/shims/python

...

  File "/Users/rjollos/Documents/Workspace/trac-dev/teo-rjollos.git/trac/db/postgres_backend.py", line 41, in <module>
    raise DistributionNotFound('psycopg2>=2.0 or psycopg2-binary', ['Trac'])
pkg_resources.DistributionNotFound: The 'psycopg2>=2.0 or psycopg2-binary' distribution was not found and is required by Trac

Previously the tests would just continue running with lots of failures.

$ make db=postgres test

Python: /Users/rjollos/.pyenv/shims/python

...

writing manifest file 'Trac.egg-info/SOURCES.txt'
python  ./trac/test.py --skip-functional-tests
EEEEEEEEEEEEEEEEEEEE.........................EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE.........................^Z
[4]+  Stopped                 make db=postgres test

I think the new behavior is better.

[Ryan J Ollos]

Proposed changes in [9310a0e83/rjollos.git].

The self.error messages were removed because I don't see a way the statements will ever be reached following the changes in #12096.

[Ryan J Ollos]

Committed to 1.2-stable in r16597, r16598, merged to trunk in r16599.

[Ryan J Ollos]

Additional change in r16600.