tf-stage1: allow setting the NS TTL of geo domains

When adding a new geo domain or doing other testing, we would want to
use a low TTL to allow for making quick changes to the configuration.

tf-stage1/archlinux.tf

@@ -366,6 +366,11 @@ locals {
   }
 
   # Domains served by machines in the geo_mirrors group
+  # Valid parameters are:
+  #   - zone_id (mandatory, either of hetznerdns_zone.{archlinux,pkgbuild}.id)
+  #   - name (mandatory, specifies the subdomain to create in the above zone)
+  #   - ttl (optional, the TTL of the NS records, defaults to 86400 if unset)
+  #
   geo_domains = {
     "geo.mirror.pkgbuild.com" = {
       zone_id = hetznerdns_zone.pkgbuild.id

tf-stage1/templates.tf

@@ -150,7 +150,7 @@ resource "hetznerdns_record" "geo_ns1" {
   name    = each.value.name
   value   = "asia.mirror.pkgbuild.com."
   type    = "NS"
-  ttl     = 86400
+  ttl     = lookup(local.geo_domains[each.key], "ttl", 86400)
 }
 
 resource "hetznerdns_record" "geo_ns2" {
@@ -160,7 +160,7 @@ resource "hetznerdns_record" "geo_ns2" {
   name    = each.value.name
   value   = "america.mirror.pkgbuild.com."
   type    = "NS"
-  ttl     = 86400
+  ttl     = lookup(local.geo_domains[each.key], "ttl", 86400)
 }
 
 resource "hetznerdns_record" "geo_ns3" {
@@ -170,5 +170,5 @@ resource "hetznerdns_record" "geo_ns3" {
   name    = each.value.name
   value   = "europe.mirror.pkgbuild.com."
   type    = "NS"
-  ttl     = 86400
+  ttl     = lookup(local.geo_domains[each.key], "ttl", 86400)
 }