Write a dynamic Terraform block for a load balancer listener rule - dynamic

Question

I'm new to dynamic blocks and am having some trouble writing rules to listeners on a load balancer that was created using for_each.
Below are the resources I created:
resource "aws_lb_listener" "app_listener_forward" {
for_each = toset(var.app_listener_ports)
load_balancer_arn = aws_lb.app_alb.arn
port = each.value
protocol = "HTTPS"
ssl_policy = "ELBSecurityPolicy-TLS-1-2-Ext-2018-06"
certificate_arn = var.ssl_cert
default_action {
type = "forward"
forward {
dynamic "target_group" {
for_each = aws_lb_target_group.app_tg
content {
arn = target_group.value["arn"]
}
}
stickiness {
enabled = true
duration = 86400
}
}
}
}
resource "aws_lb_listener_rule" "app_https_listener_rule" {
for_each = toset(var.app_listener_ports)
listener_arn = aws_lb_listener.app_listener_forward[each.value].arn
action {
type = "forward"
forward {
dynamic "target_group" {
for_each = aws_lb_target_group.app_tg
content {
arn = target_group.value["arn"]
}
}
}
}
dynamic "condition" {
for_each = var.images
path_pattern {
content {
values = condition.value["paths"]
}
}
}
}
resource "aws_lb_target_group" "app_tg" {
for_each = var.images
name = each.key
port = each.value.port
protocol = "HTTP"
target_type = "ip"
vpc_id = aws_vpc.app_vpc.id
health_check {
interval = 130
timeout = 120
healthy_threshold = 10
unhealthy_threshold = 10
}
stickiness {
type = "lb_cookie"
cookie_duration = 86400
}
}
Below are how the variables are defined:
variable "images" {
type = map(object({
app_port = number
paths = set(string)
}))
{
"app-one" = {
app_port = 3000
paths = [
"/appOne",
"/appOne/*"
]
}
"app-two" = {
app_port = 4000
paths = [
"/appTwo",
"/appTwo/*"
]
}
}
variable "app_listener_ports" {
type = list(string)
default = [
80, 443, 22, 7999, 8999
]
}
Upon executing, I am getting an error dealing with the path_pattern being unexpected:
Error: Unsupported block type
│
│ on alb.tf line 78, in resource "aws_lb_listener_rule" "app_https_listener_rule":
│ 78: path_pattern {
│
│ Blocks of type "path_pattern" are not expected here.
I've tried a few ways to get this dynamic block but am having some difficulty. Any advice would be appreciated.
Thank you!

Answer 1

Try it like this:
dynamic "condition" {
for_each = var.images
content {
path_pattern {
values = condition.value.paths
}
}
}
And change the type of paths from set(string) to list(string).

Answer 2

This is also completely acceptable:
dynamic "condition" {
for_each = var.images
content {
path_pattern {
values = condition.value["paths"]
}
}
}
However, in my opinion here it's better to not use a dynamic block for the condition to maintain readability and maintenance.
condition {
path_pattern {
values = [
"/appOne",
"/appOne/*" ## can also use variables if you prefer !!
]
}
}
I have already answered your original post related to the problem which you had after fixing the dynamic syntax.
Post URL: Error when creating dynamic terraform rule for alb listener rule