Using a custom keychain is deprecated, and it seems nearly all APIs from the Security framework expect at some point for things to go into a keychain, which doesn't work for a macOS based CLI tool meant to run in continuous integration on Linux or macOS.
I've resorted to using a private API to created a SecIdentity from a SecCertificate and a SecKey that I already have in memory.
It feels very unfortunate that I've had to do this to implement mTLS while using Foundation, because otherwise I would have to abandon Foundation (for cURL or SwiftNIO) completely simply because of this missing private API. Can Apple please expose this API officially in a future Security framework release?
Also for reference, I am not the only one using this API, I learned of it from major software projects using it as well.
