Not including folders *.dist-info breaks the plugins discovery functionality

[adferrand]

Hello!

I am trying to build a NSIS installer for Certbot (https://github.com/certbot/certbot) using pynsist. So far, I managed to create a build process that:

• gather all required dependencies
• compile the related wheels
• include them in the installre
• build the installer

However, when I try to run the software installed with the generated installer, it fails. After some digging, I understood that Certbot is using the plugins discovery functionality through package metadata. See this link https://packaging.python.org/guides/creating-and-discovering-plugins/ on section Using package metadata for more information about this mechanism.

To sum up, it requires that the package metadata are installed along with the python code of each package in the typical site-package folder of the local Python installation. These metadata take the form of a folder whose name are the package name + package version + the suffix .dist-info (for instance, metadata of future package is the folder future-0.16.0.dist-info).

However in the pkgs directory created by an installer compiled using pynsist, these *.dist-info folders are missing, thus breaking the capability of Python to use the plugins discovery functionality. Adding manually these folders corrects the problem.

Normally theses folders are automatically installed or packaged through any relevant call to pip install. In particular, they are present in the wheels generated using pip wheel, or when downloaded from PyPi. But in the code of pynsist, there is this line, when wheels are extracted to be copied in the pkg directory: https://github.com/takluyver/pynsist/blob/0108e1243fbeab2fd480ba775f04205bdceee7b2/nsist/pypi.py#L232

So *.dist-info folders are explicitly forbidden to be copied in pkgs. Similarly, there is no code done to handle the *.dist-info of the application module.

Before I open a PR, I would like to know if there is a reason why the *.dist-info folders are explicitly excluded. If not, I would make a PR to add on package_metadata to the [Include] section (default to false) of an installer.cfg, in order to allow people who need this functionality to build installers that include theses folders.

Regards, Adrien Ferrand

[takluyver]

Hello, and thanks for the detailed report. :-)

I'm pretty sure there's no good reason .dist-info directories need to be excluded. I think I wrote that line before I really knew what they were for, and they seemed to be unnecessary to make an application work, so I left them out.

Now that I know what .dist-info directories are useful for, I think I'd say we should just put them in, and don't bother adding a new option for them. Options are more complexity in the code, and another thing for people using Pynsist to figure out. I can't see any likely scenario where including the .dist-info directory would be a problem. They don't tend to be very big, and I'd rather make installers that work reliably than installers that are as small as possible.

[adferrand]

Hello @takluyver, I followed what you said. My PR does not add any configuration parameter, and copy the package metadata for wheels and for importable modules.