如何识别Terraform中的循环引用？

Question

场景

在Terraform模块中定义了SQS队列及其策略时，我遇到了一个问题，但是当试图运行terraform计划、应用甚至刷新时，我会得到以下错误。为什么？

错误

The "count" value depends on resource attributes that cannot be determined until apply, so Terraform cannot predict how many instances will be created. To work around this, use the -target argument

用户代码

module "my_sqsqueue" {
  source = "[redacted]"
  sqs_name = "${local.some_name}"
  sqs_policy        = <<EOF
  {
    "Version": "2012-10-17",
    "Id": "my_policy",
    "Statement": [
      {
        "Sid": "111",
        "Effect": "Allow",
        "Principal": {
          "AWS": "*"
        },
        "Action": "sqs:SendMessage",
        "Resource": "${module.my_sqsqueue.sqs_queue_arn}",
        "Condition": {
          "ArnEquals": {
            "aws:SourceArn": "[redacted]"
          }
        }
      }
    ]
  }
  EOF
}

模块定义

resource "aws_sqs_queue_policy" "main_queue_policy" {
  count = var.sqs_policy != "" ? 1 : 0

  queue_url = aws_sqs_queue.main_queue.id
  policy    = var.sqs_policy
}

resource "aws_sqs_queue" "main_queue" {
  content_based_deduplication       = var.sqs_content_based_deduplication
  delay_seconds                     = var.sqs_delay_seconds
  fifo_queue                        = var.sqs_fifo_queue
  kms_data_key_reuse_period_seconds = var.sqs_kms_data_key_reuse_period_seconds
  kms_master_key_id                 = var.sqs_kms_master_key_id
  max_message_size                  = var.sqs_max_message_size
  message_retention_seconds         = var.sqs_message_retention_seconds
  name                              = var.sqs_name
  receive_wait_time_seconds         = var.sqs_receive_wait_time_seconds
  visibility_timeout_seconds        = var.sqs_visibility_timeout_seconds

  tags = merge(
    {
      Name = var.sqs_name
    },
    local.default_tag_map
  )
}

Answer 1

Resource属性在sqs_policy上引用my_sqsqueue模块的输出字段，但该模块本身依赖于sqs_policy。

因此，要么：

again.

• Manually临时删除循环引用，将sqs_policy属性设置为""，然后返回引用，并在可能的情况下应用

• 定义引用。在这里，对于AWS，这是可能的，但情况并不总是这样。