enhancement: Allow subnet group to be supplied when using the database module (#51)

Author: bmonkman

modules/database/README.md

@@ -23,6 +23,7 @@ Create an RDS database.
 |------|-------------|------|---------|:--------:|
 | allowed\_security\_group\_id | The security group to allow access | `any` | n/a | yes |
 | database\_engine | Which database engine to use, currently supports `postgres` or `mysql` | `any` | n/a | yes |
+| db\_subnet\_group | The subnet group to create dbs in. The default is to use the one created by the vpc module | `string` | `""` | no |
 | environment | The environment (stage/prod) | `any` | n/a | yes |
 | instance\_class | The AWS instance class of the db | `any` | n/a | yes |
 | password\_secret\_suffix | Suffix to add to the secret that will be generated containing the database credentials | `any` | n/a | yes |

modules/database/main.tf

@@ -73,7 +73,7 @@ module "rds_postgres" {
 
   # Subnet is created by the vpc module
   create_db_subnet_group = false
-  db_subnet_group_name   = "${var.project}-${var.environment}-vpc"
+  db_subnet_group_name   = var.db_subnet_group != "" ? var.db_subnet_group : "${var.project}-${var.environment}-vpc"
 
   # DB parameter and option group
   family               = "postgres11"
@@ -123,7 +123,7 @@ module "rds_mysql" {
 
   # Subnet is created by the vpc module
   create_db_subnet_group = false
-  db_subnet_group_name   = "${var.project}-${var.environment}-vpc"
+  db_subnet_group_name   = var.db_subnet_group != "" ? var.db_subnet_group : "${var.project}-${var.environment}-vpc"
 
   # DB parameter and option group
   family               = "mysql5.7"

modules/database/variables.tf

@@ -19,6 +19,11 @@ variable "allowed_security_group_id" {
   description = "The security group to allow access"
 }
 
+variable "db_subnet_group" {
+  description = "The subnet group to create dbs in. The default is to use the one created by the vpc module"
+  default     = ""
+}
+
 variable "instance_class" {
   description = "The AWS instance class of the db"
 }