Compilation error when using async-nats as a library (related: tokio-rustls, rustls)

[nickgerace]

NATS version

0.31.0

rustc version

rustc 1.70.0 (90c541806 2023-05-31)

OS/Container environment

macOS 13.5

Steps or code to reproduce the issue

1. Use version 0.31.0
2. See that rustls version 0.21.1 is being used instead of a newer version that provides the missing method below
3. Observe the following error:

error[E0599]: no method named `with_client_auth_cert` found for struct `ConfigBuilder` in the current scope
--
  | --> third-party/rust/async-nats-0.31.0.crate/src/tls.rs:117:29
  | \|
  | 117 \|                     builder.with_client_auth_cert(cert, key).map_err(\|_\| {
  | \|                             ^^^^^^^^^^^^^^^^^^^^^ help: there is a method with a similar name: `with_no_client_auth`

Expected result

Success compilation.

Actual result

The error observed above.

[paulocsanz]

From my understanding what is going on here is that async-nats is using tokio-rustls 0.24 which pins rustls to 0.21.0.

But async-nats is using a feature from rustls that exists in 0.21.6 but not in 0.21.0.

Since it's a minor version bump, cargo seems ok to sometimes use the latest version instead of the one pinned, that's why this project compiles in some environments.

There was something going on in our enviroment, maybe a different dependency using rustls 0.21.1, so rust didn't update it to 0.21.6 when installing async-nats, because it didn't "need" to.

If async-nats wants to use a feature from a rustls version that's not exactly the one pinned in tokio-tls's cargo toml, it has to explicitly add it as a dependency, so adding rustls = "0.24.6" to async-nats cargo toml.

We added this line to our cargo toml and it fixed it, but the issue originates from this repo.

[paolobarbolini]

We added this line to our cargo toml and it fixed it, but the issue originates from this repo.

FYI if you're making a binary crate you can do cargo update -p rustls. It won't invalidate everything else you said but at least you won't need to add a line in Cargo.toml

[nepalez]

It should be fixed here #1108

[barafael]

@nickgerace can this issue be closed?

[nickgerace]

I believe so!