feat(nginx-reverse-proxy): add custom error pages and update configuration for error handling

terraform/modules/apps/nginx-reverse-proxy/config.tf

@@ -24,6 +24,7 @@ locals {
 
   services_config = {
     for k, v in var.services : "${k}.conf" => coalesce(v.config, templatefile("${path.module}/resources/nginx/conf.d/default.conf.tpl", {
+      errors     = local.error_codes
       http_port  = v.http_port
       https_port = v.https_port
       upstream   = v.upstream
@@ -46,5 +47,12 @@ locals {
 
   auth_script          = file("${path.module}/resources/auth/auth_server.py")
   auth_script_checksum = sha256(local.auth_script)
+
+  error_codes = [for f in fileset("${path.module}/resources/errors", "*.html") : split(".", f)[0]]
+  errors_pages = {
+    for f in local.error_codes :
+    "${f}.html" => file("${path.module}/resources/errors/${f}.html")
+  }
+  errors_pages_checksum = sha256(jsonencode(local.errors_pages))
 }