Yesterday I spent couple of hours on how to fix the following error:
import _ssl # if we can't import it, let the error propagate
ModuleNotFoundError: No module named '_ssl'
The error popped up during the setup process of a docker container for CI pipeline which should test a python cli tool with tox. The problem could easily be rooted to a openssl library dependency. I also tried the setup with pyenv which is an easy python environment tool but with this approach the same errors occurred. As I was already quite familiar with spack I thought how that it might be possible to fix it the ssl problem with this tool. But in the beginning it also didn’t worked out. On github you find a long issue in the pyenv repo which describes on how to setup the different CFLAGS and LDFLAGS. There I also found a good tip from Robby Dyer who wrote that if you have python version less than 3.5.2 it needs openssl 1.0.
When you run spack spec python@3.5.0. (Spack version is 0.14.2)
Input spec
--------------------------------
python@3.5.0
Concretized
--------------------------------
python@3.5.0%gcc@7.5.0+bz2+ctypes+dbm~debug+libxml2+lzma~nis~optimizations+pic+pyexpat+pythoncmd+readline+shared+sqlite3+ssl~tix~tkinter~ucs4~uuid+zlib arch=linux-ubuntu18.04-haswell
^bzip2@1.0.8%gcc@7.5.0+shared arch=linux-ubuntu18.04-haswell
^diffutils@3.7%gcc@7.5.0 arch=linux-ubuntu18.04-haswell
^libiconv@1.16%gcc@7.5.0 arch=linux-ubuntu18.04-haswell
^expat@2.2.9%gcc@7.5.0+libbsd arch=linux-ubuntu18.04-haswell
^libbsd@0.10.0%gcc@7.5.0 arch=linux-ubuntu18.04-haswell
^gdbm@1.18.1%gcc@7.5.0 arch=linux-ubuntu18.04-haswell
^readline@8.0%gcc@7.5.0 arch=linux-ubuntu18.04-haswell
^ncurses@6.1%gcc@7.5.0~symlinks~termlib arch=linux-ubuntu18.04-haswell
^pkgconf@1.6.3%gcc@7.5.0 arch=linux-ubuntu18.04-haswell
^gettext@0.20.1%gcc@7.5.0+bzip2+curses+git~libunistring+libxml2+tar+xz arch=linux-ubuntu18.04-haswell
^libxml2@2.9.9%gcc@7.5.0~python arch=linux-ubuntu18.04-haswell
^xz@5.2.4%gcc@7.5.0 arch=linux-ubuntu18.04-haswell
^zlib@1.2.11%gcc@7.5.0+optimize+pic+shared arch=linux-ubuntu18.04-haswell
^tar@1.32%gcc@7.5.0 arch=linux-ubuntu18.04-haswell
^libffi@3.2.1%gcc@7.5.0 arch=linux-ubuntu18.04-haswell
^openssl@1.1.1d%gcc@7.5.0+systemcerts arch=linux-ubuntu18.04-haswell
^perl@5.30.1%gcc@7.5.0+cpanm+shared+threads arch=linux-ubuntu18.04-haswell
^sqlite@3.30.1%gcc@7.5.0~column_metadata+fts~functions~rtree arch=linux-ubuntu18.04-haswell
you see that the openssl dependency is already related to a version 1.1.1. Having in mind the previous tip this obviously doesn’t match. Therefore I tried to install python@3.5.0 with a fixed dependency to openssl 1.0.1. Therefore I look at the available openssl versions with spack info openssl, the last openssl version was 1.0.2t To install python with this openssl version run:
spack install python@3.5.0 ^openssl@1.0.2t
The ^ (circumflex) defines the dependency to openssl. With this setup it worked smoothly 😊 Afterwards you can run spack load python@3.5.0 Happy coding!