aws_elasticsearch_domain shows persistent diff for cognito options after disabling

[ericksoen]

For the aws_elasticsearch_domain resource defined below, there is a persistent diff that appears for cognito_options when enabled=false and the other configuration options are valued. This issue only appears after at least one terraform apply cycle has been executed where enabled=true. After that cycle, subsequent executions always show a diff for cognito_options and the values are never persisted to terraform.tfstate.

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Terraform CLI and Terraform AWS Provider Version

$ terraform -v
> Terraform v0.14.7
> + provider registry.terraform.io/hashicorp/aws v3.36.0

Affected Resource(s)

• aws_elasticsearch_domain

Terraform Configuration Files

Please include all Terraform configurations required to reproduce the bug. Bug reports without a functional reproduction may be closed without investigation.

variable "vpc" { }

variable "domain" { }

variable "identity_pool_id" { }

variable "user_pool_id" { }

data "aws_vpc" "selected" {
  tags = {
    Name = var.vpc
  }
}

data "aws_subnet_ids" "selected" {
  vpc_id = data.aws_vpc.selected.id

  tags = {
    Tier = "private"
  }
}

data "aws_region" "current" {}

data "aws_caller_identity" "current" {}

data "aws_iam_policy_document" "assume" {
  statement {
    actions = ["sts:AssumeRole"]

    principals {
      type = "Service"
      identifiers = ["es.amazonaws.com"]
    }
  }
}

resource "aws_iam_role_policy" "test_policy" {
  name = "test_policy_inline"
  role = aws_iam_role.es.id

  policy = jsonencode({
      Version = "2012-10-17"
      Statement = [
        {
          Effect = "Allow"
          Action = ["cognito-idp:*", "cognito-identity:*"]
          Resource = "*"
        },
        {
          Effect = "Allow"
          Action = "iam:PassRole"
          Resource = "*"
          Condition = {
            "StringEqualsIfExists": {
              "iam:PassedToService": "cognito-identity.amazonaws.com"
            }
          }
        }
      ]
    })
}

resource "aws_iam_role" "es" {
  name = "${var.domain}-es-role"

  assume_role_policy = data.aws_iam_policy_document.assume.json
}
resource "aws_security_group" "es" {
  name        = "${var.vpc}-elasticsearch-${var.domain}"
  description = "Managed by Terraform"
  vpc_id      = data.aws_vpc.selected.id

  ingress {
    from_port = 443
    to_port   = 443
    protocol  = "tcp"

    cidr_blocks = [
      data.aws_vpc.selected.cidr_block,
    ]
  }
}

resource "aws_elasticsearch_domain" "es" {
  domain_name           = "${var.domain}-v2"
  elasticsearch_version = "6.3"

  cluster_config {
    instance_type = "t3.small.elasticsearch"
  }

  vpc_options {
    subnet_ids = [
      tolist(data.aws_subnet_ids.selected.ids)[0],
    ]

    security_group_ids = [aws_security_group.es.id]
  }

  advanced_options = {
    "rest.action.multi.allow_explicit_index" = "true"
  }

  access_policies = <<CONFIG
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Action": "es:*",
            "Principal": "*",
            "Effect": "Allow",
            "Resource": "arn:aws:es:${data.aws_region.current.name}:${data.aws_caller_identity.current.account_id}:domain/${var.domain}/*"
        }
    ]
}
CONFIG

  snapshot_options {
    automated_snapshot_start_hour = 23
  }

  ebs_options {
    ebs_enabled = true
    volume_size = 100
  }

  cognito_options {
    enabled = false
    identity_pool_id = var.identity_pool_id
    role_arn = aws_iam_role.es.arn
    user_pool_id = var.user_pool_id
  }

}

Debug Output

Panic Output

Expected Behavior

Terraform does not show a diff for any cognito options if enabled = false and there are no changes to other cognito properties like identity_pool_id, role_arn or user_pool_id.

Actual Behavior

Terraform shows diff for every apply to identity_pool_id, role_arn or user_pool_id when enabled = false.

Steps to Reproduce

1. terraform apply
2. Update enabled = true
3. terraform apply
4. Update enabled = false
5. terraform apply

Important Factoids

1. AWS API returns cognito_options with simple object when enabled = false for initial apply

$ terraform output domain | xargs -I {} aws es describe-elasticsearch-domain --domain-name {} --query DomainStatus.CognitoOptions
> { "Enabled": false }

1. Terraform state file does not show any cognito_options when enabled = false for initial apply

$ cat terraform.tfstate | jq -r '.resources[]|select(.type | startswith("aws_elasticsearch_domain"))' | jq .instances[0].attributes.cognito_options
> [ {"enabled": false, "identity_pool_id": "", "role_arn": "", "user_pool_id": "" } ]

1. Terraform debug logs show same values for CognitoOptions as returnd by the AWS CLI

CognitoOptions: {
  Enabled: false
},

1. After updating enabled=true and applying, the AWS API and Terraform state file all show the provided values for identity_pool_id, role_arn, and user_pool_id:

{
    "Enabled": true,
    "UserPoolId": "region_id",
    "IdentityPoolId": "region:guid",
    "RoleArn": "arn:aws:iam::account_id:role/tf-test-es-role"
}

1. After toggling enabled = false again and re-applying, the AWS API and Terraform state file now show conflicting representations:

• AWS CLI

{
    "Enabled": false,
    "UserPoolId": "region_id",
    "IdentityPoolId": "region:guid",
    "RoleArn": "arn:aws:iam::account_id:role/tf-test-es-role"
}

• TF State

 [ {"enabled": false, "identity_pool_id": "", "role_arn": "", "user_pool_id": "" } ]

References

• #0000

[YakDriver]

@ericksoen Ugh! Thanks for reporting this and the very detailed information. That will definitely make it easier to track down the problem. I'm not sure when we'll have a chance to tackle this. Hopefully, you or someone from the community will be able to address this.

It looks like there may already be an issue for this at #5557. (For future travelers, this does not look terribly similar to #14628.)

[ericksoen]

I'm hoping to take a look at this one at some point. For my immediate needs, I needed a GitHub issue id to add to my project source code to explain why the issue persists 😊.

Thanks for the cross-reference on #5557 (at first glance it didn't seem similar to me, but I'll review with a closer eye this time).

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[github-actions]

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