[Amazon VPC] Terraformのaws_vpcを読み解いてみた

module "vpc" {
  source     = "../../../modules/vpc"
  name       = "${var.sys_name}-${var.env}-vpc"
  cidr_block = var.vpc_cidr_block

  enable_dns_hostnames = true
  enable_dns_support   = true

  igw = {
    name = "${var.sys_name}-${var.env}-igw"
  }

  public_subnets = {
    pbsb_a = {
      name              = "${var.sys_name}-${var.env}-pbsb-a"
      cidr_block        = var.pbsb_a_cidr_block
      availability_zone = "ap-northeast-1a"
    },
    pbsb_c = {
      name              = "${var.sys_name}-${var.env}-pbsb-c"
      cidr_block        = var.pbsb_c_cidr_block
      availability_zone = "ap-northeast-1c"
    }
  }
  public_subnets_route_table = {
    name = "${var.sys_name}-${var.env}-public-rtb"
  }

  private_subnets = {
    pvsb_a = {
      name              = "${var.sys_name}-${var.env}-pvsb-a"
      cidr_block        = var.pvsb_a_cidr_block
      availability_zone = "ap-northeast-1a"
    },
    pvsb_c = {
      name              = "${var.sys_name}-${var.env}-pvsb-c"
      cidr_block        = var.pvsb_c_cidr_block
      availability_zone = "ap-northeast-1c"
    }
  }
  private_subnets_route_tables = {
    pvsb_a = {
      name = "${var.sys_name}-${var.env}-pvsb-a-rtb"
    },
    pvsb_c = {
      name = "${var.sys_name}-${var.env}-pvsb-c-rtb"
    }
  }

  env = var.env
}

variable "sys_name" {
  description = "The system name"
  type        = string
}

variable "vpc_cidr_block" {
  description = "The CIDR block for the VPC"
  type        = string
}

variable "pbsb_a_cidr_block" {
  description = "The CIDR block for the public subnet a"
  type        = string
}

variable "pbsb_c_cidr_block" {
  description = "The CIDR block for the public subnet c"
  type        = string
}

variable "pvsb_a_cidr_block" {
  description = "The CIDR block for the private subnet a"
  type        = string
}

variable "pvsb_c_cidr_block" {
  description = "The CIDR block for the private subnet c"
  type        = string
}

variable "env" {
  description = "The environment"
  type        = string
}

################################################################################
# VPC                                                                          #
################################################################################
resource "aws_vpc" "common" {
  assign_generated_ipv6_cidr_block     = var.assign_generated_ipv6_cidr_block
  cidr_block                           = var.cidr_block
  enable_dns_hostnames                 = var.enable_dns_hostnames
  enable_dns_support                   = var.enable_dns_support
  enable_network_address_usage_metrics = var.enable_network_address_usage_metrics
  instance_tenancy                     = var.instance_tenancy
  ipv4_ipam_pool_id                    = var.ipv4_ipam_pool_id
  ipv4_netmask_length                  = var.ipv4_netmask_length
  ipv6_cidr_block                      = var.ipv6_cidr_block
  ipv6_cidr_block_network_border_group = var.ipv6_cidr_block_network_border_group
  ipv6_ipam_pool_id                    = var.ipv6_ipam_pool_id
  ipv6_netmask_length                  = var.ipv6_netmask_length

  tags = {
    Name   = var.name
    Module = "vpc"
    Env    = var.env
  }
}

################################################################################
# Internet Gateway                                                             #
################################################################################
resource "aws_internet_gateway" "common" {
  vpc_id = aws_vpc.common.id

  tags = {
    Name   = var.igw.name
    Module = "vpc"
    Env    = var.env
  }
}

################################################################################
# Public Subnet                                                                #
################################################################################
resource "aws_subnet" "public" {
  for_each                                       = var.public_subnets
  assign_ipv6_address_on_creation                = each.value.assign_ipv6_address_on_creation
  availability_zone                              = each.value.availability_zone
  cidr_block                                     = each.value.cidr_block
  customer_owned_ipv4_pool                       = each.value.customer_owned_ipv4_pool
  enable_dns64                                   = each.value.enable_dns64
  enable_lni_at_device_index                     = each.value.enable_lni_at_device_index
  enable_resource_name_dns_aaaa_record_on_launch = each.value.enable_resource_name_dns_aaaa_record_on_launch
  enable_resource_name_dns_a_record_on_launch    = each.value.enable_resource_name_dns_a_record_on_launch
  ipv6_cidr_block                                = each.value.ipv6_cidr_block
  ipv6_native                                    = each.value.ipv6_native
  map_customer_owned_ip_on_launch                = each.value.map_customer_owned_ip_on_launch
  map_public_ip_on_launch                        = each.value.map_public_ip_on_launch
  outpost_arn                                    = each.value.outpost_arn
  private_dns_hostname_type_on_launch            = each.value.private_dns_hostname_type_on_launch
  vpc_id                                         = aws_vpc.common.id

  tags = {
    Name   = each.value.name
    Module = "vpc"
    Env    = var.env
  }
}

resource "aws_route_table" "public" {
  vpc_id           = aws_vpc.common.id
  propagating_vgws = var.public_subnets_route_table.propagating_vgws

  tags = {
    Name   = var.public_subnets_route_table.name
    Module = "vpc"
    Env    = var.env
  }
}

resource "aws_route" "public" {
  route_table_id         = aws_route_table.public.id
  destination_cidr_block = "0.0.0.0/0"
  gateway_id             = aws_internet_gateway.common.id
}

resource "aws_route_table_association" "public" {
  for_each       = aws_subnet.public
  route_table_id = aws_route_table.public.id
  subnet_id      = aws_subnet.public[each.key].id
}

################################################################################
# Private Subnet                                                               #
################################################################################
resource "aws_subnet" "private" {
  for_each                                       = var.private_subnets
  assign_ipv6_address_on_creation                = each.value.assign_ipv6_address_on_creation
  availability_zone                              = each.value.availability_zone
  cidr_block                                     = each.value.cidr_block
  customer_owned_ipv4_pool                       = each.value.customer_owned_ipv4_pool
  enable_dns64                                   = each.value.enable_dns64
  enable_lni_at_device_index                     = each.value.enable_lni_at_device_index
  enable_resource_name_dns_aaaa_record_on_launch = each.value.enable_resource_name_dns_aaaa_record_on_launch
  enable_resource_name_dns_a_record_on_launch    = each.value.enable_resource_name_dns_a_record_on_launch
  ipv6_cidr_block                                = each.value.ipv6_cidr_block
  ipv6_native                                    = each.value.ipv6_native
  map_customer_owned_ip_on_launch                = each.value.map_customer_owned_ip_on_launch
  map_public_ip_on_launch                        = each.value.map_public_ip_on_launch
  outpost_arn                                    = each.value.outpost_arn
  private_dns_hostname_type_on_launch            = each.value.private_dns_hostname_type_on_launch
  vpc_id                                         = aws_vpc.common.id

  tags = {
    Name   = each.value.name
    Module = "vpc"
    Env    = var.env
  }
}

resource "aws_route_table" "private" {
  for_each         = var.private_subnets_route_tables
  vpc_id           = aws_vpc.common.id
  propagating_vgws = each.value.propagating_vgws

  tags = {
    Name   = each.value.name
    Module = "vpc"
    Env    = var.env
  }
}

resource "aws_route_table_association" "private" {
  for_each       = var.private_subnets
  route_table_id = aws_route_table.private[each.key].id
  subnet_id      = aws_subnet.private[each.key].id
}

################################################################################
# VPC                                                                          #
################################################################################
variable "name" {
  description = "The name of the VPC"
  type        = string
}

variable "assign_generated_ipv6_cidr_block" {
  description = "A boolean flag to enable/disable the assignment of an IPv6 CIDR block"
  type        = bool
  default     = null
}

variable "cidr_block" {
  description = "The CIDR block for the VPC"
  type        = string
  default     = null
}

variable "enable_dns_hostnames" {
  description = "A boolean flag to enable/disable DNS hostnames in the VPC"
  type        = bool
  default     = true
}

variable "enable_dns_support" {
  description = "A boolean flag to enable/disable DNS support in the VPC"
  type        = bool
  default     = null
}

variable "enable_network_address_usage_metrics" {
  description = "A boolean flag to enable/disable network address usage metrics in the VPC"
  type        = bool
  default     = null
}

variable "instance_tenancy" {
  description = "The tenancy of instances launched into the VPC"
  type        = string
  default     = null
}

variable "ipv4_ipam_pool_id" {
  description = "The ID of the IPv4 IPAM pool"
  type        = string
  default     = null
}

variable "ipv4_netmask_length" {
  description = "The netmask length for the IPv4 CIDR block"
  type        = number
  default     = null
}

variable "ipv6_cidr_block" {
  description = "The IPv6 CIDR block"
  type        = string
  default     = null
}

variable "ipv6_cidr_block_network_border_group" {
  description = "The network border group for the IPv6 CIDR block"
  type        = string
  default     = null
}

variable "ipv6_ipam_pool_id" {
  description = "The ID of the IPv6 IPAM pool"
  type        = string
  default     = null
}

variable "ipv6_netmask_length" {
  description = "The netmask length for the IPv6 CIDR block"
  type        = number
  default     = null
}

################################################################################
# Internet Gateway                                                             #
################################################################################
variable "igw" {
  description = "The Internet Gateway"
  type = object({
    name = string
  })
}

################################################################################
# Public Subnet                                                                #
################################################################################
variable "public_subnets" {
  description = "The public subnets"
  type = map(object({
    name                                           = string
    assign_ipv6_address_on_creation                = optional(bool, null)
    availability_zone                              = string
    cidr_block                                     = string
    customer_owned_ipv4_pool                       = optional(string, null)
    enable_dns64                                   = optional(bool, null)
    enable_lni_at_device_index                     = optional(number, null)
    enable_resource_name_dns_aaaa_record_on_launch = optional(bool, null)
    enable_resource_name_dns_a_record_on_launch    = optional(bool, null)
    ipv6_cidr_block                                = optional(string, null)
    ipv6_native                                    = optional(bool, null)
    map_customer_owned_ip_on_launch                = optional(bool, null)
    map_public_ip_on_launch                        = optional(bool, null)
    outpost_arn                                    = optional(string, null)
    private_dns_hostname_type_on_launch            = optional(string, null)
  }))

  validation {
    condition     = length(keys(var.public_subnets)) > 0
    error_message = "At least one public subnet must be defined"
  }
  validation {
    condition = alltrue([
      for key in keys(var.public_subnets) : can(regex("pbsb_[a-d]", key))
    ])
    error_message = "The public subnets must be key prefixed with 'pbsb_' followed by a letter between 'a' and 'd'"
  }
}

variable "public_subnets_route_table" {
  description = "The route table"
  type = object({
    name             = string
    propagating_vgws = optional(list(string), null)
  })
}

################################################################################
# Private Subnet                                                               #
################################################################################
variable "private_subnets" {
  description = "The private subnets"
  type = map(object({
    name                                           = string
    assign_ipv6_address_on_creation                = optional(bool, null)
    availability_zone                              = string
    cidr_block                                     = string
    customer_owned_ipv4_pool                       = optional(string, null)
    enable_dns64                                   = optional(bool, null)
    enable_lni_at_device_index                     = optional(number, null)
    enable_resource_name_dns_aaaa_record_on_launch = optional(bool, null)
    enable_resource_name_dns_a_record_on_launch    = optional(bool, null)
    ipv6_cidr_block                                = optional(string, null)
    ipv6_native                                    = optional(bool, null)
    map_customer_owned_ip_on_launch                = optional(bool, null)
    map_public_ip_on_launch                        = optional(bool, null)
    outpost_arn                                    = optional(string, null)
    private_dns_hostname_type_on_launch            = optional(string, null)
  }))

  validation {
    condition     = length(keys(var.private_subnets)) > 0
    error_message = "At least one private subnet must be defined"
  }
  validation {
    condition = alltrue([
      for key in keys(var.private_subnets) : can(regex("pvsb_[a-d]", key))
    ])
    error_message = "The private subnets must be key prefixed with 'pvsb_' followed by a letter between 'a' and 'd'"
  }
}

variable "private_subnets_route_tables" {
  description = "The route table"
  type = map(object({
    name             = string
    propagating_vgws = optional(list(string), null)
  }))
}

################################################################################
# Others                                                                       #
################################################################################
variable "env" {
  description = "The environment"
  type        = string
  default     = "pvt"
}