Implementing Fine-Grained IAM Policies for Microservices with Terraform - Best Practices?
I've spent hours debugging this and I'm having trouble with I've searched everywhere and can't find a clear answer. I'm working on a personal project and Currently developing a microservices architecture on AWS, aiming to enhance our security posture using Terraform. Each microservice requires distinct permissions, but managing fine-grained IAM policies is becoming unwieldy. I've tried using the `aws_iam_policy_document` resource to create policies, but I feel like I might be missing a best practice for keeping these maintainable. Here's a snippet of what I have so far: ```hcl resource "aws_iam_policy" "service_a_policy" { name = "service-a-policy" policy = data.aws_iam_policy_document.service_a.json } data "aws_iam_policy_document" "service_a" { statement { actions = ["s3:ListBucket"] resources = ["arn:aws:s3:::my-service-a-bucket"] } } ``` While this approach works, as the number of services scales, the policy documents become cluttered and difficult to manage. I also tried using the `count` parameter for IAM resources, hoping to reduce duplication: ```hcl resource "aws_iam_policy" "service_policies" { count = length(var.service_names) name = "${var.service_names[count.index]}-policy" policy = data.aws_iam_policy_document.service_policies[count.index].json } data "aws_iam_policy_document" "service_policies" { for_each = toset(var.service_names) statement { actions = ["s3:ListBucket"] resources = ["arn:aws:s3:::my-${each.value}-bucket"] } } ``` While this reduces some redundancy, understanding which policies apply to which services at a glance is cumbersome. Looking for insights into optimizing IAM policy management with Terraform for a microservices setup. Are there established patterns or recommended practices for grouping policies or perhaps using modules? Any guidance on structuring these configurations for clarity and maintainability would be greatly appreciated. This is part of a larger API I'm building. Am I missing something obvious? I appreciate any insights! Any advice would be much appreciated. The stack includes Hcl and several other technologies.