Terraform AWS Dashboard - Widgets from nested list - terraform

Question

Terraform beginner here. I am trying to create some widgets from a nested list. Group will be a "label" widget indicating the group followed by the metric widgets for the canaries related to the group. So the dashboard should look as follows:
Group 1
widget1, widget2 etc.
Group 2
widget3, widget4 etc.
Variable value:
dashboard = [
{
name = "Group-1",
canaries = ["canary1", "canary2", "canary3"]
},
{
name = "Group-2",
canaries = ["canary4", "canary5"]
}
]
Attempt at building json:
locals {
body = [for group in var.dashboard :
#Create text widget for Group name
{
"height": 1,
"width": 24,
"y": 4,
"x": 0,
"type": "text",
"properties": {
"markdown": "\n# > [${group.name}]\n"
}
}
#Attempt to create underlying widgets for group
[for canary in group.canaries :
{
{
"height": 3,
"width": 6,
"y": 5,
"x": 0,
"type": "metric",
"properties": {
"metrics": [
[ "CloudWatchSynthetics", "Failed", "CanaryName", "${canary}", { "label": "Canary failures count", "region": "us-west-2" } ]
],
"title": "Failed canary runs",
"period": 60,
"region": "us-west-2",
"stat": "Sum",
"view": "singleValue",
"setPeriodToTimeRange": true
}
}
}
] #TF Doesn't like the inclusion of nested loop here or my syntax is incorrect.
]
}
Resource creation:
resource "aws_cloudwatch_dashboard" "canary_dashboard" {
dashboard_name = "Canary-Dashboard"
dashboard_body = jsonencode({
"widgets": concat(local.body)
})
}
In my creation of body, Terraform complains about Missing close bracket on index, but I have triple checked that I am not missing a bracket or curly brace. How do I dynamically create the dashboard widgets from nested lists?
Edit
Including desired json output below as suggested by Jordan. In the end, there will be n number of groups, each having n number of canaries belonging to said group.
{
"widgets": [
{
"height": 1,
"width": 24,
"y": 4,
"x": 0,
"type": "text",
"properties": {
"markdown": "\n# Group1\n"
}
},
{
"height": 3,
"width": 6,
"y": 5,
"x": 6,
"type": "metric",
"properties": {
"metrics": [
[ "CloudWatchSynthetics", "Failed", "CanaryName", "Group1-Canary", { "label": "Canary failures count", "region": "us-west-2" } ]
],
"title": "Failed canary runs",
"period": 60,
"region": "us-west-2",
"stat": "Sum",
"view": "singleValue",
"setPeriodToTimeRange": true
}
},
{
"height": 1,
"width": 24,
"y": 4,
"x": 0,
"type": "text",
"properties": {
"markdown": "\n# Group2\n"
}
},
{
"height": 3,
"width": 6,
"y": 5,
"x": 6,
"type": "metric",
"properties": {
"metrics": [
[ "CloudWatchSynthetics", "Failed", "CanaryName", "Group2-Canary", { "label": "Canary failures count", "region": "us-west-2" } ]
],
"title": "Failed canary runs",
"period": 60,
"region": "us-west-2",
"stat": "Sum",
"view": "singleValue",
"setPeriodToTimeRange": true
}
},
]
}

Answer 1

You're trying to do something with list comprehension that Terraform doesn't allow (see where I've marked "HERE"):
locals {
body = [for group in var.dashboard :
#Create text widget for Group name
{
"height": 1,
"width": 24,
"y": 4,
"x": 0,
"type": "text",
"properties": {
"markdown": "\n# > [${group.name}]\n"
}
} <===== HERE
#Attempt to create underlying widgets for group
[for canary in group.canaries :
{
{
"height": 3,
"width": 6,
"y": 5,
"x": 0,
"type": "metric",
"properties": {
"metrics": [
[ "CloudWatchSynthetics", "Failed", "CanaryName", "${canary}", { "label": "Canary failures count", "region": "us-west-2" } ]
],
"title": "Failed canary runs",
"period": 60,
"region": "us-west-2",
"stat": "Sum",
"view": "singleValue",
"setPeriodToTimeRange": true
}
}
}
] #TF Doesn't like the inclusion of nested loop here or my syntax is incorrect.
]
}
If TF allowed you to do what you're trying to do, you'd end up with something like:
body = [
{
"height": 1,
"width": 24,
"y": 4,
"x": 0,
"type": "text",
"properties": {
"markdown": "\n# > [${group.name}]\n"
}
},
[
{
{
"height": 3,
"width": 6,
"y": 5,
"x": 0,
"type": "metric",
"properties": {
"metrics": [
[ "CloudWatchSynthetics", "Failed", "CanaryName", "${canary}", { "label": "Canary failures count", "region": "us-west-2" } ]
],
"title": "Failed canary runs",
"period": 60,
"region": "us-west-2",
"stat": "Sum",
"view": "singleValue",
"setPeriodToTimeRange": true
}
}
},
{
{
"height": 3,
"width": 6,
"y": 5,
"x": 0,
"type": "metric",
"properties": {
"metrics": [
[ "CloudWatchSynthetics", "Failed", "CanaryName", "${canary}", { "label": "Canary failures count", "region": "us-west-2" } ]
],
"title": "Failed canary runs",
"period": 60,
"region": "us-west-2",
"stat": "Sum",
"view": "singleValue",
"setPeriodToTimeRange": true
}
}
}
]
]
And I doubt that's what you're trying to do. If you can provide a sample of what you'd like the JSON to look like, we can show you how to achieve it.