Add gc_policy to Bigtable module.

Column families have now a new property, to specify the garbage collection
policy. A new option also allows to set a default policy if none is specified.

This changes the previous syntax for column families, that was helpful since the
policy is column-family specific, the new syntax makes it easier to specify a
policy per column family.

modules/bigtable-instance/variables.tf

@@ -19,7 +19,7 @@ variable "autoscaling_config" {
   type = object({
     min_nodes      = number
     max_nodes      = number
-    cpu_target     = number,
+    cpu_target     = number
     storage_target = optional(number, null)
   })
   default = null
@@ -31,6 +31,18 @@ variable "cluster_id" {
   default     = "europe-west1"
 }
 
+variable "default_gc_policy" {
+  description = "Default garbage collection policy, to be applied to all column families and all tables. Can be override in the tables variable for specific column families."
+  type = object({
+    deletion_policy = optional(string)
+    gc_rules        = optional(string)
+    mode            = optional(string)
+    max_age         = optional(string)
+    max_version     = optional(string)
+  })
+  default = null
+}
+
 variable "deletion_protection" {
   description = "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."
   default     = true
@@ -41,6 +53,7 @@ variable "display_name" {
   default     = null
 }
 
+
 variable "iam" {
   description = "IAM bindings for topic in {ROLE => [MEMBERS]} format."
   type        = map(list(string))
@@ -79,8 +92,17 @@ variable "tables" {
   description = "Tables to be created in the BigTable instance."
   nullable    = false
   type = map(object({
-    split_keys      = optional(list(string), [])
-    column_families = optional(list(string), [])
+    split_keys = optional(list(string), [])
+    column_families = optional(map(object(
+      {
+        gc_policy = optional(object({
+          deletion_policy = optional(string)
+          gc_rules        = optional(string)
+          mode            = optional(string)
+          max_age         = optional(string)
+          max_version     = optional(string)
+        }), null)
+    })), {})
   }))
   default = {}
 }