Add Global Database support

schubergphilis · Dec 31, 2024 · bfbd0b7 · bfbd0b7
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diff --git a/.gitignore b/.gitignore
@@ -1,5 +1,6 @@
 #  Local .terraform directories
 **/.terraform/*
+*.lock.hcl
 
 # .tfstate files
 *.tfstate

diff --git a/README.md b/README.md
@@ -17,7 +17,7 @@ This can be changed by updating `var.instance_count`. By default all instances u
 
 | Name | Version |
 |------|---------|
-| <a name="requirement_terraform"></a> [terraform](#requirement\_terraform) | >= 1.3 |
+| <a name="requirement_terraform"></a> [terraform](#requirement\_terraform) | >= 1.8 |
 | <a name="requirement_aws"></a> [aws](#requirement\_aws) | >= 5.81.0 |
 
 ## Providers
@@ -30,7 +30,7 @@ This can be changed by updating `var.instance_count`. By default all instances u
 
 | Name | Source | Version |
 |------|--------|---------|
-| <a name="module_rds_enhanced_monitoring_role"></a> [rds\_enhanced\_monitoring\_role](#module\_rds\_enhanced\_monitoring\_role) | github.com/schubergphilis/terraform-aws-mcaf-role | v0.3.3 |
+| <a name="module_rds_enhanced_monitoring_role"></a> [rds\_enhanced\_monitoring\_role](#module\_rds\_enhanced\_monitoring\_role) | schubergphilis/mcaf-role/aws | ~> 0.4.0 |
 
 ## Resources
 
@@ -43,8 +43,10 @@ This can be changed by updating `var.instance_count`. By default all instances u
 | [aws_rds_cluster_instance.first](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/rds_cluster_instance) | resource |
 | [aws_rds_cluster_instance.rest](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/rds_cluster_instance) | resource |
 | [aws_rds_cluster_parameter_group.default](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/rds_cluster_parameter_group) | resource |
+| [aws_rds_global_cluster.default](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/rds_global_cluster) | resource |
 | [aws_security_group.default](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/security_group) | resource |
 | [aws_vpc_security_group_ingress_rule.default](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/vpc_security_group_ingress_rule) | resource |
+| [aws_kms_alias.rds](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/kms_alias) | data source |
 | [aws_subnet.selected](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/subnet) | data source |
 
 ## Inputs
@@ -75,13 +77,15 @@ This can be changed by updating `var.instance_count`. By default all instances u
 | <a name="input_engine_mode"></a> [engine\_mode](#input\_engine\_mode) | The engine mode of the Aurora cluster | `string` | `"provisioned"` | no |
 | <a name="input_engine_version"></a> [engine\_version](#input\_engine\_version) | The engine version of the Aurora cluster | `string` | `null` | no |
 | <a name="input_final_snapshot_identifier"></a> [final\_snapshot\_identifier](#input\_final\_snapshot\_identifier) | Identifier of the final snapshot to create before deleting the cluster | `string` | `null` | no |
+| <a name="input_global_database_primary"></a> [global\_database\_primary](#input\_global\_database\_primary) | Whether the cluster is part of a global database as the primary cluster | `bool` | `false` | no |
+| <a name="input_global_database_secondary"></a> [global\_database\_secondary](#input\_global\_database\_secondary) | Whether the cluster is part of a global database as the seconday cluster | <pre>object({<br>    global_cluster_identifier      = string<br>    enable_global_write_forwarding = optional(bool, true)<br>  })</pre> | `null` | no |
 | <a name="input_iam_database_authentication_enabled"></a> [iam\_database\_authentication\_enabled](#input\_iam\_database\_authentication\_enabled) | Specify if mapping AWS IAM accounts to database accounts is enabled. | `bool` | `true` | no |
 | <a name="input_iam_roles"></a> [iam\_roles](#input\_iam\_roles) | A list of IAM Role ARNs to associate with the cluster | `list(string)` | `null` | no |
 | <a name="input_instance_class"></a> [instance\_class](#input\_instance\_class) | The class of RDS instances to attach to the cluster instances (not used when `engine_mode` set to `serverless`) | `string` | `null` | no |
 | <a name="input_instance_config"></a> [instance\_config](#input\_instance\_config) | Map of instance specific settings that override values set elsewhere in the module, map keys should match instance number | <pre>map(object({<br>    instance_class = optional(string, null)<br>    promotion_tier = optional(number, null)<br>  }))</pre> | `null` | no |
 | <a name="input_instance_count"></a> [instance\_count](#input\_instance\_count) | The number of RDS instances to attach (not used when `engine_mode` set to `serverless`) | `number` | `2` | no |
 | <a name="input_iops"></a> [iops](#input\_iops) | The amount of Provisioned IOPS to be initially allocated for each DB instance. (Required for Multi-AZ DB cluster) | `number` | `null` | no |
-| <a name="input_kms_key_id"></a> [kms\_key\_id](#input\_kms\_key\_id) | ID of KMS key to encrypt storage and performance insights data | `string` | `null` | no |
+| <a name="input_kms_key_id"></a> [kms\_key\_id](#input\_kms\_key\_id) | ARN of KMS key to encrypt storage and performance insights data | `string` | `null` | no |
 | <a name="input_manage_master_user"></a> [manage\_master\_user](#input\_manage\_master\_user) | Set to false to provide a custom password using `master_password` | `bool` | `true` | no |
 | <a name="input_master_password"></a> [master\_password](#input\_master\_password) | Password for the master DB user, must set `manage_master_user` to false if specifying a custom password | `string` | `null` | no |
 | <a name="input_master_user_secret_kms_key_id"></a> [master\_user\_secret\_kms\_key\_id](#input\_master\_user\_secret\_kms\_key\_id) | ID of KMS key to encrypt the master user Secrets Manager secret | `string` | `null` | no |
@@ -114,6 +118,7 @@ This can be changed by updating `var.instance_count`. By default all instances u
 | <a name="output_custom_endpoints"></a> [custom\_endpoints](#output\_custom\_endpoints) | The DNS addresses of the custom endpoints. |
 | <a name="output_database"></a> [database](#output\_database) | Name of the first database created when the cluster was created |
 | <a name="output_endpoint"></a> [endpoint](#output\_endpoint) | DNS address of the RDS instance |
+| <a name="output_global_cluster_identifier"></a> [global\_cluster\_identifier](#output\_global\_cluster\_identifier) | If the cluster is the primary of a global cluster, the global cluster ID |
 | <a name="output_id"></a> [id](#output\_id) | ID of the Aurora cluster |
 | <a name="output_instance_ids"></a> [instance\_ids](#output\_instance\_ids) | Aurora instances IDs |
 | <a name="output_master_user_secret"></a> [master\_user\_secret](#output\_master\_user\_secret) | The generated database master user secret when `var.manage_master_user` is set to `true` |

diff --git a/examples/global-database/main.tf b/examples/global-database/main.tf
@@ -0,0 +1,105 @@
+locals {
+  vpc_cidr = "10.0.0.0/16"
+
+  azs_primary   = slice(data.aws_availability_zones.available_primary.names, 0, 3)
+  azs_secondary = slice(data.aws_availability_zones.available_secondary.names, 0, 3)
+}
+
+# Primary region
+data "aws_availability_zones" "available_primary" {}
+
+provider "aws" {
+  alias  = "primary"
+  region = "eu-west-1"
+}
+
+module "vpc_primary" {
+  source  = "terraform-aws-modules/vpc/aws"
+  version = "~> 4.0"
+
+  name             = "example"
+  azs              = local.azs_primary
+  cidr             = local.vpc_cidr
+  database_subnets = [for k, v in local.azs_primary : cidrsubnet(local.vpc_cidr, 8, k + 6)]
+  private_subnets  = [for k, v in local.azs_primary : cidrsubnet(local.vpc_cidr, 8, k + 3)]
+  public_subnets   = [for k, v in local.azs_primary : cidrsubnet(local.vpc_cidr, 8, k)]
+}
+
+resource "random_string" "master_password" {
+  length  = 16
+  special = false
+}
+
+module "aurora_primary" {
+  providers = {
+    aws = aws.primary
+  }
+
+  source = "../.."
+
+  name                    = "example"
+  engine                  = "postgresql"
+  engine_mode             = "serverlessv2"
+  engine_version          = "16.4"
+  global_database_primary = true
+  instance_count          = 2 # 1 Writer, 1 Reader
+  master_password         = random_string.master_password.result
+  subnet_ids              = module.vpc_primary.private_subnets
+
+  security_group_ingress_rules = [
+    {
+      cidr_ipv4   = local.vpc_cidr
+      description = "Allow access from the VPC CIDR range"
+    }
+  ]
+}
+
+# Secondary region
+provider "aws" {
+  alias  = "secondary"
+  region = "eu-central-1"
+}
+
+data "aws_availability_zones" "available_secondary" {}
+
+module "vpc_secondary" {
+  providers = {
+    aws = aws.secondary
+  }
+
+  source  = "terraform-aws-modules/vpc/aws"
+  version = "~> 4.0"
+
+  name             = "example"
+  azs              = local.azs_secondary
+  cidr             = local.vpc_cidr
+  database_subnets = [for k, v in local.azs_secondary : cidrsubnet(local.vpc_cidr, 8, k + 6)]
+  private_subnets  = [for k, v in local.azs_secondary : cidrsubnet(local.vpc_cidr, 8, k + 3)]
+  public_subnets   = [for k, v in local.azs_secondary : cidrsubnet(local.vpc_cidr, 8, k)]
+}
+
+module "aurora_secondary" {
+  providers = {
+    aws = aws.secondary
+  }
+
+  source = "../.."
+
+  name           = "example"
+  engine         = "postgresql"
+  engine_mode    = "serverlessv2"
+  engine_version = "16.4"
+  instance_count = 1 # 1 Reader
+  subnet_ids     = module.vpc_secondary.private_subnets
+
+  global_database_secondary = {
+    global_cluster_identifier = module.aurora_primary.global_cluster_identifier
+  }
+
+  security_group_ingress_rules = [
+    {
+      cidr_ipv4   = local.vpc_cidr
+      description = "Allow access from the VPC CIDR range"
+    }
+  ]
+}
diff --git a/examples/global-database/versions.tf b/examples/global-database/versions.tf
@@ -0,0 +1,13 @@
+terraform {
+  required_providers {
+    aws = {
+      source  = "hashicorp/aws"
+      version = ">= 5.81.0"
+    }
+    random = {
+      source  = "hashicorp/random"
+      version = ">= 3.4.0"
+    }
+  }
+  required_version = ">= 1.8"
+}
diff --git a/main.tf b/main.tf
@@ -2,6 +2,11 @@ locals {
   instance_class      = var.engine_mode == "serverlessv2" ? "db.serverless" : var.instance_class
   skip_final_snapshot = var.final_snapshot_identifier == null
 
+  global_cluster_identifier = var.global_database_primary ? aws_rds_global_cluster.default[0].id : var.global_database_secondary != null ? var.global_database_secondary.global_cluster_identifier : null
+
+  // For a secondary cluster, the KMS key must be specified explicitly even if defaulted to the AWS Managed alias ("For encrypted cross-region replica, kmsKeyId should be explicitly specified").
+  kms_key_arn = var.global_database_secondary != null && var.storage_encrypted && var.kms_key_id == null ? data.aws_kms_alias.rds.target_key_arn : var.kms_key_id
+
   // Backtrack is only supported for MySQL clusters
   backtrack_window = {
     "mysql"      = var.backtrack_window
@@ -21,7 +26,7 @@ locals {
   }[var.engine]
 
   // Default master username to use unless otherwise specified
-  master_username = var.master_username != null ? var.master_username : {
+  master_username = var.master_username != null || var.global_database_secondary != null ? var.master_username : {
     "mysql"      = "root"
     "postgresql" = "postgres"
   }[var.engine]
@@ -31,6 +36,25 @@ data "aws_subnet" "selected" {
   id = var.subnet_ids[0]
 }
 
+################################################################################
+# Global Database
+################################################################################
+
+data "aws_kms_alias" "rds" {
+  name = "alias/aws/rds"
+}
+
+resource "aws_rds_global_cluster" "default" {
+  count = var.global_database_primary ? 1 : 0
+
+  global_cluster_identifier = "${var.name}-global"
+  engine                    = "aurora-${var.engine}"
+  engine_version            = var.engine_version
+  database_name             = var.database
+  storage_encrypted         = var.storage_encrypted
+  tags                      = var.tags
+}
+
 ################################################################################
 # Cluster
 ################################################################################
@@ -51,14 +75,16 @@ resource "aws_rds_cluster" "default" {
   deletion_protection                 = var.deletion_protection
   enable_http_endpoint                = var.enable_http_endpoint
   enabled_cloudwatch_logs_exports     = var.enable_cloudwatch_logs_exports ? local.enabled_cloudwatch_logs_exports : null
+  enable_global_write_forwarding      = var.global_database_secondary != null ? var.global_database_secondary.enable_global_write_forwarding : null
   engine                              = "aurora-${var.engine}"
   engine_mode                         = var.engine_mode == "serverlessv2" ? "provisioned" : var.engine_mode
   engine_version                      = var.engine_version
   final_snapshot_identifier           = var.final_snapshot_identifier
+  global_cluster_identifier           = local.global_cluster_identifier
   iam_database_authentication_enabled = var.iam_database_authentication_enabled
   iam_roles                           = var.iam_roles
   iops                                = var.iops
-  kms_key_id                          = var.kms_key_id
+  kms_key_id                          = local.kms_key_arn
   manage_master_user_password         = var.manage_master_user ? var.manage_master_user : null
   master_password                     = var.master_password
   master_user_secret_kms_key_id       = var.master_user_secret_kms_key_id
@@ -93,6 +119,10 @@ resource "aws_rds_cluster" "default" {
       seconds_until_auto_pause = var.min_capacity == 0 ? var.seconds_until_auto_pause : null
     }
   }
+
+  lifecycle {
+    ignore_changes = [replication_source_identifier]
+  }
 }
 
 ################################################################################
@@ -140,7 +170,7 @@ resource "aws_rds_cluster_instance" "first" {
   monitoring_interval                   = var.monitoring_interval
   monitoring_role_arn                   = try(module.rds_enhanced_monitoring_role[0].arn, null)
   performance_insights_enabled          = var.performance_insights
-  performance_insights_kms_key_id       = var.performance_insights ? var.kms_key_id : null
+  performance_insights_kms_key_id       = var.performance_insights ? local.kms_key_arn : null
   performance_insights_retention_period = var.performance_insights ? var.performance_insights_retention_period : null
   promotion_tier                        = try(var.instance_config[count.index + 1]["promotion_tier"], null)
   publicly_accessible                   = var.publicly_accessible
@@ -164,7 +194,7 @@ resource "aws_rds_cluster_instance" "rest" {
   monitoring_interval                   = var.monitoring_interval
   monitoring_role_arn                   = try(module.rds_enhanced_monitoring_role[0].arn, null)
   performance_insights_enabled          = var.performance_insights
-  performance_insights_kms_key_id       = var.performance_insights ? var.kms_key_id : null
+  performance_insights_kms_key_id       = var.performance_insights ? local.kms_key_arn : null
   performance_insights_retention_period = var.performance_insights ? var.performance_insights_retention_period : null
   promotion_tier                        = try(var.instance_config[count.index + 2]["promotion_tier"], null)
   publicly_accessible                   = var.publicly_accessible

diff --git a/outputs.tf b/outputs.tf
@@ -23,6 +23,11 @@ output "database" {
   description = "Name of the first database created when the cluster was created"
 }
 
+output "global_cluster_identifier" {
+  value       = var.global_database_primary ? aws_rds_global_cluster.default[0].id : null
+  description = "If the cluster is the primary of a global cluster, the global cluster ID"
+}
+
 output "endpoint" {
   value       = aws_rds_cluster.default.endpoint
   description = "DNS address of the RDS instance"

diff --git a/variables.tf b/variables.tf
@@ -89,6 +89,11 @@ variable "database" {
   type        = string
   default     = null
   description = "The name of the first database to be created when the cluster is created"
+
+  validation {
+    condition     = (var.global_database_secondary != null && var.database == null) || var.global_database_secondary == null
+    error_message = "Cannot specify database name for global secondary cluster"
+  }
 }
 
 variable "database_parameters" {
@@ -174,6 +179,26 @@ variable "final_snapshot_identifier" {
   description = "Identifier of the final snapshot to create before deleting the cluster"
 }
 
+variable "global_database_primary" {
+  type        = bool
+  default     = false
+  description = "Whether the cluster is part of a global database as the primary cluster"
+}
+
+variable "global_database_secondary" {
+  type = object({
+    global_cluster_identifier      = string
+    enable_global_write_forwarding = optional(bool, true)
+  })
+  default     = null
+  description = "Whether the cluster is part of a global database as the seconday cluster"
+
+  validation {
+    condition     = !(var.global_database_primary && var.global_database_secondary != null)
+    error_message = "Cannot configure a cluster as both primary and secondary in a global database"
+  }
+}
+
 variable "iam_database_authentication_enabled" {
   type        = bool
   default     = true
@@ -216,19 +241,29 @@ variable "iops" {
 variable "kms_key_id" {
   type        = string
   default     = null
-  description = "ID of KMS key to encrypt storage and performance insights data"
+  description = "ARN of KMS key to encrypt storage and performance insights data"
 }
 
 variable "manage_master_user" {
   type        = bool
   default     = true
   description = "Set to false to provide a custom password using `master_password`"
+
+  validation {
+    condition     = var.global_database_primary == false || (var.global_database_primary && var.manage_master_user == false)
+    error_message = "Cannot enable manage_master_user for a global database"
+  }
 }
 
 variable "master_password" {
   type        = string
   default     = null
   description = "Password for the master DB user, must set `manage_master_user` to false if specifying a custom password"
+
+  validation {
+    condition     = (var.global_database_secondary != null && var.master_password == null) || var.global_database_secondary == null
+    error_message = "Cannot specify master_password for global secondary cluster"
+  }
 }
 
 variable "master_user_secret_kms_key_id" {
@@ -241,6 +276,11 @@ variable "master_username" {
   type        = string
   default     = null
   description = "Username for the master DB user"
+
+  validation {
+    condition     = (var.global_database_secondary != null && var.master_username == null) || var.global_database_secondary == null
+    error_message = "Cannot specify master_username for global secondary cluster"
+  }
 }
 
 variable "max_capacity" {

diff --git a/versions.tf b/versions.tf
@@ -5,5 +5,5 @@ terraform {
       version = ">= 5.81.0"
     }
   }
-  required_version = ">= 1.3"
+  required_version = ">= 1.8"
 }