Search for MIT krb5 installation on Windows

[steffen-kiess]

This code was mostly copied from the python-gssapi project. The only changes were changing the name of the library and changing the formatting to make the CI happy.

[jborean93]

I would be very reluctant on adding this as MIT krb5 for Windows supports a widely different set of APIs than what their Linux releases do. We also don't ship any wheels for Windows right now so for an end user to install this library they would require the dlls to be present anyway to build the module on Windows negating the need to search for the dll at runtime.

Ultimately before we could look into this we would need to

• Add testing in CI for Windows, or at least to an extent where we can build and import the module at least
• Determine if we want to create pre-built wheels for Windows
• Determine if we want to ship the krb5 dlls inside our wheel or do what python-gssapi does and just have them as a dependency

[steffen-kiess]

Add testing in CI for Windows, or at least to an extent where we can build and import the module at least

I might look into this at some point if I can find the time.

Determine if we want to create pre-built wheels for Windows

I think this might be a good idea.

Determine if we want to ship the krb5 dlls inside our wheel or do what python-gssapi does and just have them as a dependency

I think doing the same thing as python-gssapi would be a good idea. Reasons for that are that:

• If both pykrb5 and python-gssapi are used (or pykrb5 and some other library which depends on libkrb5) it would be good if they end up using the same instance of libkrb5 so that e.g. MEMORY: ccaches are shared. If pykrb5 brings its own library then either there will be two libkrb5 instances in the process (which won't share resources) or which libkrb5 instance will be used depends on the ordering of imports.
• In general the user will have to install and configure krb5 anyway (for example provide a C:\ProgramData\MIT\Kerberos5\krb5.ini which contains the correct realm configuration), and then it is better to the global krb5 installation instead of installing another one.