SignatureV4a implementation in smithy

[justin-masse]

Hey team,

I saw the new sigv4a stuff got rolled in this week and had a question -- does this smithy change get picked up by the @aws-sdk/signature-v4-multi-region package eventually then? Thus reducing the need for the aws-crt binaries in a lambda runtime (which fixes JS build tools like esbuild/webpack not having the crt binaries).

I am just curious if that's how this usually works? Otherwise do we need to use smithy/signature-v4a directly?

[kuhe]

The JavaScript implementation of sigv4a must be (opt-in) imported to execute its module-level code, functioning in the same way as the @aws-sdk/signature-v4-crt package.

The instructions are here: https://github.com/aws/aws-sdk-js-v3/tree/main?tab=readme-ov-file#installing-the-javascript-sigv4a-dependency

And yes, it should avoid the problems with locating the binaries that affect @aws-sdk/signature-v4-crt.