Feature flag to compile a binary dynamically linked to system OpenSSL

[folliehiyuki]

Describe the problem you are trying to solve

I really like the idea behind tremor, and I'm interested in packaging it for AlpineLinux. To meet the packaging requirements, rust packages should be dynamically linked to system-provided OpenSSL library when possible. Also, ring crate used by rustls cannot be built yet on a few architectures that AlpineLinux supports (e.g. s390x, riscv64, ppc64le).

Describe the solution you'd like

A feature flag to build tremor linked to system OpenSSL. This feature flag should come with some changes to the dependencies:

• hyper-openssl instead of hyper-rustls
• elasticsearch and reqwest built with native-tls feature

I'm not familiar with all the crates inside Cargo.toml file so the above list might not be exhaustive.

[folliehiyuki]

Another head up (not related to OpenSSL but also a system library linked issue): onig_sys (a dependency of grok crate) currently can't be built with clang16 (see rust-onig/rust-onig#174).

So, can you vendor the patch in that PR inside the repo? That would be really helpful for downstream packaging, since rust-onig maintainer has been inactive for a while.

[Licenser]

Good ideas! We'll put it on the list but I can't make promises as to when we'd get to it.