hard time installing the python bindings

[ctorres-addc]

Would you please care to explain how to install the python bindings, I already built the code and I don't know how to make this library available to python. Thank you.

[rwmjones]

So you probably want to know first of all that this isn't the main libnbd repo, that's: https://gitlab.com/nbdkit/libnbd

But in answer to your question, can you give a bit more information like .. what system you're using, what you've tried, and that sort of thing?

[ctorres-addc]

Thank you for the quick response, so I'm using ubuntu 22.04 and I installed a package called virtnbdbackup: https://github.com/abbbi/virtnbdbackup which creates full backups for running virtual machines. The virtnbdbackup package has a "python3-libnbd" dependency, unfortunately the "python3-libnbd" package provided by ubuntu is an old version "1.10.5-1". So I downloaded the latest tarball https://download.libguestfs.org/libnbd/1.16-stable/libnbd-1.16.3.tar.gz. I followed the instructions to build it:

./configure
make
make check

It built the code without any errors, the problem is that I don't know how to integrate the python library that was built into the ubuntu's python packages. Since you are the author I was hoping that maybe you could guide me in the right direction.

Thank you.

[rwmjones]

One way to use libnbd & python is to use the ./run script in the directory after you have built the package. You do not need to install it, in fact, installing it is a bad idea. Just do:

/path/to/libnbd/run yourprogram

which will set up some PYTHON* and LD_LIBRARY_PATH environment variables so that the version from the build directory is used. It's best to examine the ./run script to see what it does as it is quite simple.

Another way would be to use a Python virtualenv, but TBH I'm not very familiar with how that would work with the libnbd bindings. We might be able to add support for building a venv possibly. (@nirs any ideas??)

[ctorres-addc]

Thank you.

[nirs]

Another way would be to use a Python virtualenv, but TBH I'm not very familiar with how that would work with the libnbd bindings. We might be able to add support for building a venv possibly. (@nirs any ideas??)

There is a script for creating venv here:
https://github.com/abbbi/virtnbdbackup/blob/master/venv/create.sh

I tested the basic steps and they work. But the venv does not isolate from
libnbd.so dependencies, so it may break because of old libraries on the host.

I think a better way would be to install virtnbdbackup in a container:
https://github.com/abbbi/virtnbdbackup/tree/master/docker

[ctorres-addc]

Unfortunately a docker container is not an option for this project, however the solution you suggested about running the program this way kind of works:

/path/to/libnbd/run yourprogram

The above solution tries to run virtnbdbackup but then it throws the following error:

File "/home/addc/libnbd-1.16.3/python/nbd.py", line 34, in <module> import libnbdmod ModuleNotFoundError: No module named 'libnbdmod'

Then I checked the libnbd python directory and the libnbdmod.py is missing, however there is a libnbdmod.c, it looks like the libnbdmod.py is not being generated at built time.

[nirs]

@ctorres-addc did you check the script for creating venv?
https://github.com/abbbi/virtnbdbackup/blob/master/venv/create.sh

[rwmjones]

File "/home/addc/libnbd-1.16.3/python/nbd.py", line 34, in <module> import libnbdmod ModuleNotFoundError: No module named 'libnbdmod'

Then I checked the libnbd python directory and the libnbdmod.py is missing, however there is a libnbdmod.c, it looks like the libnbdmod.py is not being generated at built time.

There should exist python/.libs/libnbdmod.cpython-312-x86_64-linux-gnu.so (possibly with a slightly different name). This is libnbdmod — this module is written in C, not Python. ./run adds python/.libs to PYTHONPATH so the library is picked up.

[rwmjones]

To be clear there is never any file called libnbdmod.py

[ctorres-addc]

F

or some reason python/.libs is missing. Do you have any idea why this might be?

[rwmjones]

It doesn't look like anything was built in the python directory.

Did it detect Python during the ./configure step and did it build without errors?

What happens if you do make -C python check ?

[ctorres-addc]

Hello, this is what I get when I run ./configure :
configure.log

and this is what I get when I run make -C python check :

[rwmjones]

Python wasn't configured. You need to install libpython3-dev (or it might be python3-dev)

[rwmjones]

Or install all the build dependencies listed here: https://salsa.debian.org/debian/libnbd/-/blob/debian/master/debian/control