Workload Identity Federation should support ECS Fargate container credentials

[dwiajik]

Is your feature request related to a problem? Please describe.
I am trying to use Workload Identity Federation on AWS ECS Fargate. It seems that AwsCredentials.getAwsSecurityCredentials (code) only supports EC2 metadata service and does not support ECS Fargate container credential URL.

Describe the solution you'd like
Google auth SDK should support ECS Fargate container credential URL through environment variable AWS_CONTAINER_CREDENTIALS_RELATIVE_URI.

Describe alternatives you've considered
The alternative to use Workload Identity Federation on ECS Fargate is implementing the REST authentication myself.

[mdaniel]

Google auth SDK should support ECS Fargate through environment variable AWS_CONTAINER_CREDENTIALS_RELATIVE_URI.

And AWS_CONTAINER_CREDENTIALS_FULL_URI, too, please, so it can work in CloudShell

[ismailsimsek]

+1 having same issue

[jurgispods]

I provided a PR for this issue: #1374, feedback welcome!