Legacy dependencies cause duplicated crates and larger binaries

[gekh]

Describe the feature

Current duplicate dependencies:
• legacy-hyper-rustls
• legacy-rustls

These legacy dependencies force inclusion of older versions like rustls v0.21.12, which leads to duplicated crates in the build. This significantly increases binary size, especially problematic for use cases like AWS Lambda, where larger binaries impact cold start time.

Request:
Please remove these legacy dependencies from the default feature set to avoid unnecessary duplication and bloat in downstream builds.

Use Case

I’m building lightweight Rust applications for AWS Lambda, where binary size directly impacts cold start time. The inclusion of legacy-hyper-rustls and legacy-rustls causes duplicate versions of rustls (such as v0.21.12) to be pulled in, even when I’m already using the latest rustls elsewhere in my project. This bloats the binary and slows down startup performance, which is critical in serverless environments.

Proposed Solution

Remove legacy-hyper-rustls and legacy-rustls from the default feature set. This allows users to opt into legacy support only when explicitly needed, avoiding unnecessary dependency duplication and keeping builds minimal by default.

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

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[landonxjames]

We are keeping the legacy dependencies in for backwards compatibility purposes and likely will for some time into the future. But you are in luck, it is possible today to disable including those dependencies in your compilation. There are instructions in the announcement of our move to hyper-1x #1257. I can't seem to link to sections of a discussion, but search for How do I disable compiling the legacy hyper + rustls crates? to see the specific instructions.

[gekh]

Thanks for your fast reply, @landonxjames

I’ve tried the features you recommended, but they didn’t work.
I’m testing this basic setup for DynamoDB:

aws-config = { version = "1.8.4", default-features = false, features = ["behavior-version-latest", "rt-tokio", "default-https-client"]}
aws-sdk-dynamodb = { version = "1.87.0", default-features = false, features = ["behavior-version-latest", "rt-tokio", "default-https-client"]}

I removed sigv4a feature as it doesn't exist. The other features don't fix the issue. Actually the binary even bloated more :D

As I see in sources in deafult-client you use "dep:rustls-native-certs" which is mentioned here

[dependencies.legacy-hyper-rustls]
package = "hyper-rustls"
version = "0.24"
features = ["rustls-native-certs", "http2"]
optional = true

So that it gets old hyper-rustls and old rustls itself as a secondary dep to it. It seems there’s no way to disable this “legacy” dependency via feature flags.

Do you have any other suggestions on how to fix or avoid this?

[SorsDeMaTete]

those bloated libraries are disgusting