How to loop within a nested block

Terraform
1

Hi,

I’m having trouble understanding how to create a loop for my resource below. I need to create two of these resources and the variable of which the number of resources is dependent on is within the nested block “dimensions”, “instance = var.instance”, (highlighted in bold - which represents the disk partitions on an EC2 instance). From my understanding after reading some documentation, I cannot use the count parameter for this?

resource “aws_cloudwatch_metric_alarm” “disk_percentage_low” {
alarm_name = “disk_percentage_low”
comparison_operator = “LessThanOrEqualToThreshold”
evaluation_periods = “1”
metric_name = “disk_used_percent”
namespace = “AWS/CWAgent”
period = “60”
statistic = “Average”
threshold = “20”
alarm_description = “This metric monitors ec2 disk utilization”
actions_enabled = “true”
alarm_actions = [aws_sns_topic.disk_alarm.arn]
insufficient_data_actions =

dimensions = {
instanceid = var.instanceid
instance = var.instance
instancetype = var.instancetype
imageid = var.imageid
}
}

My vague understanding is that I need to use the dynamic “tag” and the “for_each” expression?

I would really appreciate any help. Thanks for your time.

2

Hi,

I’ve now figured out how to do this. Please go ahead and close this, thanks.

3

The way to do this is the following:

resource “aws_cloudwatch_metric_alarm” “disk_percentage_low” {

for_each = toset(var.instance)

alarm_name = “disk_percentage_low_${each.value}”
comparison_operator = “LessThanOrEqualToThreshold”
evaluation_periods = “1”
metric_name = “LogicalDisk % Free Space”
namespace = “CWAgent”
period = “60”
statistic = “Average”
threshold = “20”
alarm_description = “This metric monitors ec2 disk utilization”
actions_enabled = “true”
alarm_actions = [aws_sns_topic.disk_alarm.arn]
insufficient_data_actions =

dimensions = {
InstanceId = var.InstanceId
InstanceType = var.InstanceType
ImageId = var.ImageId
instance = each.value
objectname = var.objectname
}
}

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