Terraform, variables, interpolation and networking

• tipos nativos: strings, maps (key=value), list ([])
  • boolean no es nativo
• localización:
  • en el cuerpo de script
  • por línea de comando o entono
  • en un fichero adicional de variables
  • más información: terraform variables

• variable "nombre_variable" {
    default = "valor por defecto"
  }
   
  variable "localizaciones" {
    type = map
    default = {
      location1 = "xxxx"
      location2 = "yyyy"
    }
  }

• testeando variables y su uso:

  variable "server_name" {
      default = "web-server"
  }
   
  variable "locations" {
      type = "map"
      default = {
          location1 = "xxx"
          location2 = "yyy"
      }
  }
   
  variable "subnets" {
      type = "list"
      default = ["10.0.1.10","10.0.1.11"]
  }
   
  variable "live" {
    type = "string"
    default = true
  }

  • terraform console
    • var.server_name
    • var.locations[«location1»]
    • var.locations.location1
    • var.subnets[0]
    • var.live

• uso variables [de entorno] para almacenar credenciales
• TF_VAR_<NOMBRE> definida como variable de entorno del sistema

• variables
  • var.<nombre>
• resources
  • <resource>.<nombre>.<atributo>
• data: recoger un dato del estado
  • data.<resource>.<nombre>.<atributo>

• variable "subscription_id" {
   
  }
   
  #suponiendo que está en el entorno
  provider "azurerm" {
      version         = ">=1.27"
      client_id       = "6c609608-a350-476f-85ff-eaff7e82f981"
      client_secret   = "qW0S]tToc]=]ub8HM7yciLSnwOWh1emD"
      tenant_id       = "c8537169-fe81-494a-a2dd-b4ea067073a1"
      subscription_id = var.subscription_id
      features {}
  }

• https://azure.microsoft.com/en-us/global-infrastructure/regions/
• https://azure.microsoft.com/en-us/global-infrastructure/geographies/
• https://azure.microsoft.com/en-us/global-infrastructure/services/
• az login –service-principal -u $TF_VAR_client_id -p $TF_VAR_client_secret -t $TF_VAR_tenant_id
• az account list-locations -o table
• az login [–username | -u] <username> [–password | -p ] <password>

• agrupación lógica de recursos bajo tu criterio
• cada resource* ha de ir en resource group

• terraform.tfvars

  web_server_location = "westus2"
  web_server_rg = "web-rg"

• logical isolates network
• espacio IP
• creació de subnets
• conexión con otras VNET, VPN o Endpoints
• NSG = Network Security Groups (firewall básico)

• resource_prefix = "web-server"
  web_server_address_space = "1.0.0.0/22"

variable "resource_prefix" {}
variable "web_server_address_space" {}
 
resource "azurerm_virtual_network" "web_server_vnet" {
  name = "${var.resource_prefix}-vnet"
  location = var.web_server_location
  resource_group_name = azurerm_resource_group.web_server_rg.name
  address_space = [var.web_server_address_space]
}

• decirle a Terraform en que orden se deben crear los recursos
• al crear elementos que dependen (o no) de otros, se pueden dar los siguientes casos:
  • que no haya dependencia
  • dependencia indirecta: Terraform la asume o las dedice de las variables
  • dependencia directa (o explícita): usando la propiedad depends_on

• subnetwork en nuestra VNET
• address space
• segmentación
• NSG = Network Security Groups

• terraform.tfvars

  web_server_address_prefix = "1.0.1.0/24

subnet.tf

variable web_server_address_prefix {}
 
resource "axzurerm_subnet" "web_server_subnet"{
  name = "${var.resource_prefix}-subnet"
  resource_group_name = azurerm_resource_group.web_server_rg.name
  virtual_network_name = azurerm_virtual_network.web_server_vnet.name
  address_prefix = var.web_server_address_prefix
}

• equivalencia con el mundo real
• atachar a Subnets/VNET
• IP públicas o privadas
• Estáticas o dinámicas
• DNS Settings
• NSG

• terraform.tfvars

  web_server_name = "web-01"

nic.tf

  variable web_server_name {}
  resource "azurerm_network_interface" "web_server_nic" {
    name = "${var.web_server_name}-nic"
    location = var.web_server_location
    resource_group_name = azurerm_resource_group.web_server_rg.name
 
    ip_configuration {
      name = "${var.web_server_name}-ip"
      subnet_id = azurerm_subnet.web_server_subnet.id
      private_ip_address_allocation = "dynamic" 
    }
  }