[FEAT]: AWS SigV4 support with the client

[karthikchejerla]

Describe the enhancement

Ability to sign requests using AWS Signature V4

Why is this needed?

Signing requests using native clients has been an essential requirement for accessing the Amazon OpenSearch Service on AWS using fine grained access controls. Having native SigV4 support in clients avoids the need to use cURL requests and other workarounds.

How do you think it should be done?

Reference: https://opensearch.org/blog/aws-sigv4-support-for-clients/

Some ideas to get started

• https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-signing.html
• https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-auth-using-authorization-header.html
• https://github.com/lucasweb78/aws-v4-signer-java

[jillesvangurp]

would you be able to help with this? I lack access to an aws opensearch cluster to test this. I'd prefer a solution that works on all platforms.

[jillesvangurp]

https://github.com/KotlinCrypto this library looks good as a multiplatform implementation for sha256.

If somebody wants to have a go at this, the rest client is pretty easy to extend.