storage_target is an optional setting

modules/bigtable-instance/README.md

@@ -98,7 +98,7 @@ module "bigtable-instance" {
 | [name](variables.tf#L56) | The name of the Cloud Bigtable instance. | <code>string</code> | ✓ |  |
 | [project_id](variables.tf#L67) | Id of the project where datasets will be created. | <code>string</code> | ✓ |  |
 | [zone](variables.tf#L99) | The zone to create the Cloud Bigtable cluster in. | <code>string</code> | ✓ |  |
-| [autoscaling_config](variables.tf#L17) | Settings for autoscaling of the instance. Only one of autoscaling_config or num_nodes should be set. If both are set, num_nodes is ignored. | <code title="object&#40;&#123;&#10;  min_nodes      &#61; number&#10;  max_nodes      &#61; number&#10;  cpu_target     &#61; number&#10;  storage_target &#61; number&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
+| [autoscaling_config](variables.tf#L17) | Settings for autoscaling of the instance. Only one of autoscaling_config or num_nodes should be set. If both are set, num_nodes is ignored. | <code title="object&#40;&#123;&#10;  min_nodes      &#61; number&#10;  max_nodes      &#61; number&#10;  cpu_target     &#61; number,&#10;  storage_target &#61; optional&#40;number, null&#41;&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
 | [cluster_id](variables.tf#L28) | The ID of the Cloud Bigtable cluster. | <code>string</code> |  | <code>&#34;europe-west1&#34;</code> |
 | [deletion_protection](variables.tf#L34) | Whether or not to allow Terraform to destroy the instance. Unless this field is set to false in Terraform state, a terraform destroy or terraform apply that would delete the instance will fail. | <code></code> |  | <code>true</code> |
 | [display_name](variables.tf#L39) | The human-readable display name of the Bigtable instance. | <code></code> |  | <code>null</code> |

modules/bigtable-instance/variables.tf

@@ -19,8 +19,8 @@ variable "autoscaling_config" {
   type = object({
     min_nodes      = number
     max_nodes      = number
-    cpu_target     = number
-    storage_target = number
+    cpu_target     = number,
+    storage_target = optional(number, null)
   })
   default = null
 }