Demonstração de ideia para criação de policies dinâmicas com attach em múltiplos users e roles.

main.tf

# terraform.tfvars
policies = [
  {
    policy_name = "policy-alpha",
    roles_to_attach = []
    users_to_attach = ["user1", "user2"]
    content = {}
  },
  {
    policy_name = "policy-beta",
    roles_to_attach = []
    users_to_attach = ["user1", "user2"]
    content = {}
  }
]

# Resultado que eu gostaria de gerar atrávés de resources com count e usando local para pré-processar.
resource "aws_iam_policy" "policy" {
  name = value["policy_alpha"]
  policy = value["policy_alpha"].content
}

resource "aws_iam_policy" "policy" {
  name = value["policy_beta"]
  policy = value["policy_beta"].content
}

resource "aws_iam_user_policy_attachment" "attach_users" {
  user       = "policy_alpha"
  policy_arn = "user1"
}

resource "aws_iam_user_policy_attachment" "attach_users" {
  user       = "policy_alpha"
  policy_arn = "user2"
}

resource "aws_iam_user_policy_attachment" "attach_users" {
  user       = "policy_beta"
  policy_arn = "user1"
}

resource "aws_iam_user_policy_attachment" "attach_users" {
  user       = "policy_beta"
  policy_arn = "user2"
}