Terraform create a Cloudwatch rule with multiple targets - amazon-web-services

Question

From the Terraform docs - https://www.terraform.io/docs/providers/aws/r/cloudwatch_event_target.html
I don't see an option to map multiple targets to the same Cloudwatch rule. It only takes an arn field which accepts one resource. I'm trying to map 5 Lambdas to the same Cloudwatch rule. Does Terraform support this?
EDIT: How can I attach only 5 lambdas? If I've created 15 lambdas, I want to attach 5 each to 3 cloudwatch rules.

Answer 1

Got it working! I had to divide the count of the rules by 5 when I assigned targets to rules. This is roughly what it looks like:
resource "aws_cloudwatch_event_rule" "arule" {
count = "${ceil(length(var.lambda_arns) / 5.0)}" // Needs to be 5.0 to force float computation
name = "${var.rule_name}${format("-%d", count.index)}"
is_enabled = true
}
resource "aws_cloudwatch_event_target" "atarget" {
depends_on = ["aws_cloudwatch_event_rule.arule"]
count = "${length(var.lambda_arns)}"
rule = "${aws_cloudwatch_event_rule.arule.*.name[count.index / 5]}"
arn = "${var.lambda_arns[count.index]}"
}
I created the event rules based on the number of lambdas (i.e., if there are 10 lambdas, 2 rules are created).
I created the targets based on number of lambdas (i.e., if there are 10 lambdas, 10 targets are created).
I assigned the targets proportionally among the rules by dividing the count.index by 5 (the same logic used to determine the count of rules).

Answer 2

Assuming you created all your lambas using the same terraform resource with count, you can use count on this as well:
resource "aws_cloudwatch_event_target" "cw_target" {
count = length(aws_lambda_function.my_lambdas)
rule = "${aws_cloudwatch_event_rule.my_rule.name}"
arn = "${aws_lambda_function.my_lambdas.*.arn[count.index]}"
}

Answer 3

Here is what I did. I ignore the "target_id" of resource "aws_cloudwatch_event_target" (very important), and use local variables (define your local vars, this example: "targets"), and looping for the local vars, and creating multiple aws_cloudwatch_event_target, and multiple assessment templates.
locals {
stack_name_prefix = "Inspector"
rules_package_arn_cis = "arn:aws:inspector:ap-southeast-2:454640832652:rulespackage/0-Vkd2Vxjq"
default_target = {
rules : [local.rules_package_arn_cis],
duration : 3600
}
targets = [
merge(local.default_target, {
name : "data_indexer",
tags : {
Function = "LR - DX"
},
}),
merge(local.default_target, {
name : "ai_engine",
tags : {
Function = "LR - AIE"
},
}),
merge(local.default_target, {
name : "data_processor",
tags : {
Function = "LR - Data Processor"
},
}),
merge(local.default_target, {
name : "platform_manager",
tags : {
Function = "LR - PM"
},
})
]
}
resource "aws_inspector_assessment_template" "assessment_template" {
count = length(local.targets)
name = "${local.stack_name_prefix}_${local.targets[count.index]["name"]}_assessment_template"
target_arn = aws_inspector_assessment_target.assessment[count.index].arn
duration = local.default_target.duration
rules_package_arns = [local.rules_package_arn_cis]
}
resource "aws_cloudwatch_event_target" "event_target_for_inspector_assessment_template" {
count = length(local.targets)
rule = aws_cloudwatch_event_rule.event_rule_for_inspector_assessment_template.name
// target_id = "amazon_inspector_assessment" ## Don't USE target_id, it will mess up the cloudwatch event target, and only generated one target instead of 4
arn = aws_inspector_assessment_template.assessment_template[count.index].arn
role_arn = aws_iam_role.inspector_assessment_template.arn
}

Answer 4

module "eventbridgetarget" {
for_each = var.rule_and_target_details
source = "git::ssh://git#bitbucket.int.ally.com/tf/terraform-modules-aws-eventbridge.git//modules/target?ref=v1"
rule_arn = module.eventbridgerule.rule.arn
name = each.value.name
namespace = module.namespace.lower_short_name
tags = module.namespace.tags
#arn = module.lambda.arn
arn = each.value.arn
}
Now in the tfvars pass the value like below:
rule_and_target_details = {
"firsttarget" = {
name = "getentities"
arn = "arn:aws:execute-api:us-east-1:2XXXXXXX:92mchkioeh/api/GET/getEntities"
}
"secondtarget" = {
name = "getactivitylog"
arn = "arn:aws:execute-api:us-east-1:2XXXXXX:92mchkioeh/api/GET/getActivityLog"
}
"thirdtarget" = {
name = "searchactivitylog"
arn = "arn:aws:execute-api:us-east-1:XXXXXX:92mchkioeh/api/GET/searchActivityLog"
}
}