How can I allow a Group to assume a Role?

Question

How can I allow all members of a Group to assume a Role in AWS IAM?

I tried Using the following statement but as specified in AWS IAM Principal Element, a Group can not be a Principal.

I want to achieve something like below:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "",
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::***:group/developer"
      },
      "Action": "sts:AssumeRole"
    }
  ]
}

The idea is that all members of the group group/developer should be able to assume the role. The objective is that I should be saved from having to specify each member in a group individually.

Is there a way to achieve this?

Answer 1

Attach a policy to the Group that grants permission to call sts:AssumeRole on the desired Role:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "123",
            "Effect": "Allow",
            "Action": [
                "sts:AssumeRole"
            ],
            "Resource": [
                "arn:aws:iam::123456789012:role/desired-role"
            ]
        }
    ]
}

Also, attach a Trust Policy on the Role. The sample policy (below) trusts any user in the account, but they would also need sts:AssumeRole permissions (above) to assume the role.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::123456789012:root"
      },
      "Action": "sts:AssumeRole"
    }
  ]
}