Python Docker images are missing dbm.gnu support

[sebk-666]

Hi,
I tested multiple of the official Python 3.x Docker images and they all are missing support for dbm.gnu.
While there is a <lib>/dbm/gnu.py file that imports _gdbm, the corresponding _gdbm.cpython.*.solibrary in <lib>/lib-dynload/ is missing.

I tested on python:3.4, python:3.5, python:3.6, python:3.4-alpine - all with the same result.

# python3
Python 3.4.5 (default, Sep 24 2016, 05:29:30)
[GCC 4.9.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import dbm.gnu
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.4/dbm/gnu.py", line 3, in <module>
    from _gdbm import *
ImportError: No module named '_gdbm'

Sebastian

[yosifkit]

Looks like we need libgdbm-dev and since we already are adding it to ruby images I think this makes it a candidate for addition to buildpack-deps so they can share the layer. As a bonus it won't increase the image size by much:

After this operation, 167 kB of additional disk space will be used.

We'll still need to add the appropriate packages to slim and alpine variants here, but I've started a PR to add it to buildpack-deps. docker-library/buildpack-deps#49

[tianon]

Appears this was resolved with docker-library/buildpack-deps#49 / #153. 🎉

$ docker pull python:3
3: Pulling from library/python
Digest: sha256:4748e00099548b67f250ee6f1210f1f5675113948ed0aae48e195ad6c8e12a32
Status: Image is up to date for python:3

$ docker run -it --rm python:3
Python 3.6.5 (default, Mar 31 2018, 01:15:58) 
[GCC 4.9.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import dbm.gnu
>>>