Proxy support for ProcessCredentialsProvider

[jaecktec]

Describe the feature

Allow passing of environment variables to ProcessCredentialsProvider so it's possible to support for example proxy with aws_signing_helper

Use Case

Example Use-Case:
using IamAuthAnywere with the aws_signing_helper inside a locked down environment it is neccisary to set the environment variable http_proxy / https_proxy.

Proposed Solution

extend the ProcessCredentialsProvider.Builder to accept environments and forward it to ProcessBuilder.

Other Information

it's possible to expose these variables as global, but it's already cumbersome to set all the different jvm proxy props, having them as additional global variables would make it even more confusing.

Acknowledgements

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

AWS Java SDK version used

2.20.161

JDK version used

openjdk 11.0.19 2023-04-18 LTS

Operating System and version

[debora-ito]

@jaecktec thank you for reaching out, and apologies for the long silence. To add support for environment variables in the ProcessCredentialsProvider we need to have a proper discussion with the other SDK teams, we want to provide a consistent experience across all the AWS SDKs.

I'll move this to the cross-SDK aws/aws-sdk repo to start the discussion process. I'll close your PR in the meantime. We can re-open later on if needed.

[debora-ito]

Transferring back to the Java SDK v2 repo.