New publish API

[ehuss]

This is a meta-issue to track various different requests related to publishing that will require a new API. Feel free to add any I've missed!

• New method to uploading the crate payload: #57. (Primarily for timeouts?)
• Some sort of feedback to know when the crate is successfully added to the index. I'm not sure if this is possible without polling from Cargo.
• Pre-flight validation before uploading and before building the crate.
  • https://github.com/rust-lang/cargo/issues/4300 — keyword validation

  • 41 — Aligning validation (would be much easier if it was all server-side).

  • https://github.com/rust-lang/cargo/issues/8221 — Check email validation before uploading.
  • https://github.com/rust-lang/cargo/issues/3662 — Another early validation request.
  • https://github.com/rust-lang/crates.io/issues/1515 — "dry run" validation
• Publishing multiple crates at once, atomically (either all "pass" or all "fail").
  • https://github.com/rust-lang/cargo/issues/1169 — publish --all

See also:

• Tangential notes on publish API: https://github.com/rust-lang/crates.io/issues/1522

Prior art

• npm is proposing a "staged" publish model where the packages are actually published, but gated with a --staged flag, until a manual step is performed to "approve" the publish: https://github.com/npm/rfcs/pull/92. Could be interesting to consider!
  • A similar request for an "approval" step: https://github.com/rust-lang/rfcs/pull/2947#issuecomment-648871616