Terraform Gcp Https Load Balancer Google_Compute_Url_Map with Variable Length of Host_Rule Blocks
I'm a Terraform Novice Creating Gcp External Http/Https Load Balancers That Route Different Hostnames to Different Backends. in a Working Proof of Concept, I...
I'm a Terraform novice creating GCP external HTTP/HTTPS load balancers that route different hostnames to different backends. In a working proof of concept, I have two hostnames supported, like this:
locals {
hostnames = [ "", "" ]
}
resource "google_compute_url_map" "MY_URL_MAP_HTTPS" {
name = "mylb-https"
description = "External HTTPS load balancer for multiple hostnames"
host_rule {
hosts = [ local.hostnames[0] ]
path_matcher = "site1-path-matcher"
}
host_rule {
hosts = [ local.hostnames[1] ]
path_matcher = "site2-path-matcher"
}
path_matcher {
name = "site1-path-matcher"
default_service = "projects/myproject/global/backendServices/site1-backend-service"
}
path_matcher {
name = "site2-path-matcher"
default_service = "projects/myproject/global/backendServices/site2-backend-service"
}
}
I know I can do a for loop when Terraform expects a list, such as associating multiple SSL certificates with a target proxy:
resource "google_compute_ssl_certificate" "MY_SSL_CERT" {
count = length(local.hostnames)
name = replace(local.hostnames[count.index], ".", "-")
}
resource "google_compute_target_https_proxy" "MY_TARGET_PROXY_HTTPS" {
ssl_certificates = [
for cert in google_compute_ssl_certificate.MY_SSL_CERT
cert.id
]
}
But how can a do a for loop on the host_rule and path_matcher blocks? Is this possible?
1 Answer
Found a bug report which helped me see dynamic blocks are the solution:
variable "hostnames" {
type = list(string)
default = null
}
resource "google_compute_url_map" "URL_MAP_HTTPS" {
name = "urlmap-https"
default_service = google_compute_backend_bucket.default.id
dynamic "host_rule" {
for_each = var.hostnames
content {
hosts = [ host_rule.value]
path_matcher = "path-matcher-${host_rule.key}"
}
}
dynamic "path_matcher" {
for_each = var.hostnames
content {
name = "path-matcher-${path_matcher.key}"
default_service = google_compute_backend_service.default[path_matcher.key].id
}
}
}
This is also the solution to having a variable number of backend blocks to use with google_compute_backend_service and google_compute_region_backend_service.
Sarah Jenkins is a veteran tech journalist with over 12 years of experience covering artificial intelligence, mobile innovations, and digital ethics. Her insights have appeared in leading technology publications worldwide.
