IamAwsProvider can't fetch ECS task role credentials

[cbutcosk]

In using the new credentials interface I noticed that although IamAwsProvider covers the EC2 metadata auth flow. But when I try to use it in an ECS task role the auth flow is getting tripped up here.

According to the AWS docs around IAM Task Roles the expected response from the container metadata endpoint lacks the Code property checked in that line:

{
    "AccessKeyId": "XXX",
    "Expiration": "2020-11-07T01:28:43Z",
    "RoleArn": "arn:aws:iam::XXX:role/role-name-here",
    "SecretAccessKey": "XXX",
    "Token": "XXX"
}

[balamurugana]

@cbutcosk Could you confirm AWS_CONTAINER_CREDENTIALS_FULL_URI way to fetch credentials return same JSON structure?

[cbutcosk]

@balamurugana Hm, good question--I actually can't reproduce an environment on my end that sets AWS_CONTAINER_CREDENTIALS_FULL_URI. Not sure if that is due to the deployment type I'm using or something.

That said the AWS SDK appears to use the same endpoint regardless of which environment variable is used to construct the URI since the entire refresh() method is in the superclass there.

[balamurugana]

@cbutcosk No problem. I have made Code property check optional.