Support aws config files and/or credential_process for S3 #823
Description
For particularly complicated authentication flows, such as AWS IAM Roles Anywhere, it's very helpful to be able to use credential_process credentials. Typically this would be configured via an AWS config file, but that's always seemed to me to be an overcomplication, and I'd be perfectly happy with an explicit credential process auth_method.
While the gimme-aws-creds recommendation would work for a brief time, federated AWS credentials tend to expire pretty quickly. For roles that are chained, the maximum session length is only an hour, non-extendable!
credential_process makes lots of flows possible that aren't possible otherwise, and only requires implementing a simple and well-established contract with the process that gets run. I'd love to see it in bazel-remote.