choose a crypto_provider for rustls_cert_gen

[stormshield-gt]

From the release 0.12 of rcgen #202 , we must now choose ring or aws_lc_rc as a feature.
Because rustls_cert_gen has default-features = false, its build is currently broken.

This PR activate aws_lc_rc feature, because soon it will get RSA key generation support aws/aws-lc-rs#296 , so it will provide more options. Edit: we switched to using ring to match the rcgen default.

But we could also change it to default to whatever rcgen default or use ring as default depending on your preferences.

[cpu]

Thanks for the PR!

Because rustls_cert_gen has default-features = false, its build is currently broken.

It sounds like there's CI coverage missing for this tool that would detect this broken state :-( Would you be willing to update your PR to add that coverage as well?

[stormshield-gt]

It's a feature unification problem, when we build at a workspace level, all features get unified so the ring feature from rcgen is also added to rustls_cert_gen that's why the CI doesn't catch it.

One solution is to add a CI job with cargo build --package rustls-cert-gen or to use an external tools like cargo hack, as shown in this thread

Which solution do you prefer?

[cpu]

It's a feature unification problem

Aha, that makes sense 💡 Thank you

One solution is to add a CI job with cargo build --package rustls-cert-gen

That sounds good to me. We're using cargo hack in some other Rustls projects so I'm not opposed to that solution if another maintainer prefers it, but I think we can start with the simplest option.

[stormshield-gt]

We see that's the new job failed the CI as expected https://github.com/rustls/rcgen/actions/runs/7499266190 , I will now push the fix

[cpu]

Thanks!

[cpu]

This feels small and obvious enough to merge without blocking on an additional review. If there's any post-merge feedback I will commit to implementing it.