Terraform for loop - amazon-web-services

Question

I've been learning terraform, and have been playing with dashboards.
I have the following file which generates a dashboard.
resource "aws_cloudwatch_dashboard" "main" {
dashboard_name = "sample_dashboard"
dashboard_body = <<EOF
{
"widgets": [
${templatefile("${path.module}/cpu.tmpl", { ids = aws_instance.web[*].id })},
${templatefile("${path.module}/network.tmpl", { ids = aws_instance.web[*].id })}
]
}
EOF
}
Here is the cpu template file.
{
"type": "metric",
"x": 0,
"y": 0,
"width": 12,
"height": 6,
"properties": {
"metrics": ${jsonencode([for id in ids : ["AWS/EC2","CPUUtilization","InstanceId", "${id}"]])},
"period": 300,
"stat": "Average",
"region": "us-east-1",
"title": "EC2 Instance CPU"
}
}
Here have the network template file.
{
"type": "metric",
"x": 12,
"y": 0,
"width": 12,
"height": 6,
"properties": {
"metrics": ${jsonencode([for id in ids :
["AWS/EC2", "NetworkIn", "InstanceId", "${id}"]
])},
"period": 300,
"stat": "Average",
"region": "us-east-1",
"title": "EC2 Instance Network"
}
}
Everything works as expected, and I get the following dashboard.
The problem I'm having is when trying to add another metric in the for loop I get an error.
{
"type": "metric",
"x": 12,
"y": 0,
"width": 12,
"height": 6,
"properties": {
"metrics": ${jsonencode([for id in ids :
["AWS/EC2", "NetworkIn", "InstanceId", "${id}"],
["AWS/EC2", "NetworkOut", "InstanceId", "${id}"]
])},
"period": 300,
"stat": "Average",
"region": "us-east-1",
"title": "EC2 Instance Network"
}
}
I get the following error.
Call to function "templatefile" failed: ./network.tmpl:9,70-71:
Invalid 'for' expression; Extra characters after the end of the 'for'
expression..
As always thanks in advance for you help.

Answer 1

One way to overcome the issue would be to concat your metrics:
{
"type": "metric",
"x": 12,
"y": 0,
"width": 12,
"height": 6,
"properties": {
"metrics": ${jsonencode(concat([for id in ids :
["AWS/EC2", "NetworkIn", "InstanceId", "${id}"]
], [for id in ids :
["AWS/EC2", "NetworkOut", "InstanceId", "${id}"]
]))},
"period": 300,
"stat": "Average",
"region": "us-east-1",
"title": "EC2 Instance Network"
}
}