locals.tf file - parsing jsonencode body - terraform

Question

Wondering if anyone has ran tackled it. So, I need to be able to generate list of egress CIDR blocks that is currently available for listing over an API. Sample output is the following:
[
{
"description": "blahnet-public-acl",
"metadata": {
"broadcast": "192.168.1.191",
"cidr": "192.168.1.128/26",
"ip": "192.168.1.128",
"ip_range": {
"start": "192.168.1.128",
"end": "192.168.1.191"
},
"netmask": "255.255.255.192",
"network": "192.168.1.128",
"prefix": "26",
"size": "64"
}
},
{
"description": "blahnet-public-acl",
"metadata": {
"broadcast": "192.168.160.127",
"cidr": "192.168.160.0/25",
"ip": "192.168.160.0",
"ip_range": {
"start": "192.168.160.0",
"end": "192.168.160.127"
},
"netmask": "255.255.255.128",
"network": "192.168.160.0",
"prefix": "25",
"size": "128"
}
}
]
So, I need convert it to Azure Firewall
###############################################################################
# Firewall Rules - Allow Access To TEST VMs
###############################################################################
resource "azurerm_firewall_network_rule_collection" "azure-firewall-azure-test-access" {
for_each = local.egress_ips
name = "azure-firewall-azure-test-rule"
azure_firewall_name = azurerm_firewall.public_to_test.name
resource_group_name = var.resource_group_name
priority = 105
action = "Allow"
rule {
name = "test-access"
source_addresses = local.egress_ips[each.key]
destination_ports = ["43043"]
destination_addresses = ["172.16.0.*"]
protocols = [ "TCP"]
}
}
So, bottom line is that allowed IP addresses have to be a list of strings for the "source_addresses" parameter, such as this:
["192.168.44.0/24","192.168.7.0/27","192.168.196.0/24","192.168.229.0/24","192.168.138.0/25",]
I configured data_sources.tf file:
data "http" "allowed_networks_v1" {
url = "https://testapiserver.com/api/allowed/networks/v1"
}
...and in locals.tf, I need to configure
locals {
allowed_networks_json = jsondecode(data.http.allowed_networks_v1.body)
egress_ips = ...
}
...and that's where I am stuck. How can parse that data in locals.tf file so I can reference it from within TF ?
Thanks a metric ton!!

Answer 1

I'm assuming that the list of string you are referring to are the objects under: metadata.cidr we can extract that with a for loop in a local, and also do a distinct just in case we get duplicates.
Here is a sample code
data "http" "allowed_networks_v1" {
url = "https://raw.githack.com/heldersepu/hs-scripts/master/json/networks.json"
}
locals {
allowed_networks_json = jsondecode(data.http.allowed_networks_v1.body)
distinct_cidrs = distinct(flatten([
for key, value in local.allowed_networks_json : [
value.metadata.cidr
]
]))
}
output "data" {
value = local.distinct_cidrs
}
and here is the output of a plan on that:
terraform plan
An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
Terraform will perform the following actions:
Plan: 0 to add, 0 to change, 0 to destroy.
Changes to Outputs:
+ data = [
+ "192.168.1.128/26",
+ "192.168.160.0/25",
]
Here is the code for your second sample:
data "http" "allowed_networks_v1" {
url = "https://raw.githack.com/akamalov/testfile/master/networks.json"
}
locals {
allowed_networks_json = jsondecode(data.http.allowed_networks_v1.body)
distinct_cidrs = distinct(flatten([
for key, value in local.allowed_networks_json.egress_nat_ranges : [
value.metadata.cidr
]
]))
}
output "data" {
value = local.distinct_cidrs
}