Finding .so files without setting LD_LIBRARY_PATH

[Paul Smith]

Hi all.  I have a locally-built version of Python (2.7.11) that I'm
copying around to different systems, running all different versions of
GNU/Linux.  Because I need this to work across systems I'm bundling
important .so's with my Python installation (libcrypto, libssl,
libreadline, libgmp) which are dynamically loaded when I do things like
"import ssl" etc.

I have a wrapper script around this Python that everyone runs, rather
than invoking it directly, and it is able to set some environment
variables etc.  So, I had been setting LD_LIBRARY_PATH before I invoke
Python so it can find the "right" versions of libcrypto.so etc.

That works fine, but here's the problem: because LD_LIBRARY_PATH is in
Python's environment it is also passed down to programs invoked by
Python.  That means if I (for example) invoke subprocess.call(['ssh',
...]) then it fails because the system ssh is looking for the system
libcrypto.so, and when it finds the Python libcrypto.so instead
(because of LD_LIBRARY_PATH) it fails.

What I'd like to do is have a way of setting the library path that
Python uses when it tries to load .so files (for example in the ssl
module which loads lib-dynload/_ssl.so which links to libssl.so and
libcrypto.so), WITHOUT setting LD_LIBRARY_PATH in the environment that
Python passes to its children.

Is there any way to do this?

It seems like there must be some way to do it, because if after I start
python with LD_LIBRARY_PATH set, then I delete it from os.environ, then
I import ssl it works, so it's still set in Python's environment.  But
I don't want to have to modify all my scripts to unset LD_LIBRARY_PATH,
plus that's not the right thing to do in case someone needs to set
LD_LIBRARY_PATH for themselves.

What I've tried so far is writing a little Python script that unsets
LD_LIBRARY_PATH and setting PYTHONSETUP to the name of that script in
my wrapper, which does seem to work, but that takes away the ability
for users to use PYTHONSETUP themselves which is sub-optimal.

Does anyone have any other ideas?