Infra Automation by Terraform Dynamic Block for Map(Objects) Usecase— Part6

Dynamic blocks in Terraform are used when you want to generate multiple instances of a block within a resource or module dynamically. This is particularly useful when you have a variable number of similar configurations to define. One common use case for dynamic blocks is when you’re working with a map of objects, and you want to generate a block for each object in the map.

Here’s a simple use case to illustrate the use of dynamic blocks:

Let’s say you have a map of objects consists of routing rules, and you want to create Azure Front door Routing rules using Terraform. The rules are defined by a object of maps, where each map object contains the details of a routing rule.

Azure Front Door with Dynamic Block

// main.tf
 

dynamic "routing_rule" {
    for_each = var.routing_rule
    content {
      name               = routing_rule.value.name
      accepted_protocols = routing_rule.value.accepted_protocols
      patterns_to_match  = routing_rule.value.patterns_to_match
      frontend_endpoints = routing_rule.value.frontend_endpoints
      dynamic "forwarding_configuration" {
         for_each = routing_rule.value.configuration == "Forwarding" ? [routing_rule.value.forwarding_configuration] : []
        content {
          forwarding_protocol = routing_rule.value.forwarding_configuration.forwarding_protocol
          backend_pool_name   = routing_rule.value.forwarding_configuration.backend_pool_name
        }
      }
    }
  }

// variables.tf

variable "routing_rule"{
    type = Map(object())
    description = "This is name of the location"
   
}
// terraform.tfvars

routing_rule = {
    rr1 = {
      name               = "exampleRoutingRule1"
      frontend_endpoints = ["exampleFrontendEndpoint1"]
      accepted_protocols = ["Http", "Https"] 
      patterns_to_match  = ["/*"]           
      enabled            = true              
      configuration      = "Forwarding"        
      forwarding_configuration = {
        backend_pool_name                     = "exampleBackendBing1"
        cache_enabled                         = false       
        cache_use_dynamic_compression         = false       
        cache_query_parameter_strip_directive = "StripAll"
        forwarding_protocol                   = "HttpsOnly"   
      }
      redirect_configuration = {
        custom_host         = ""             
        redirect_protocol   = "MatchRequest"   
        redirect_type       = "Found"        
        custom_fragment     = ""
        custom_path         = ""
        custom_query_string = ""
      }
    } 
}

Commands to execute the Terraform modules

change to the directory 
terraform init
terraform plan -var-file=/home/azureuser/Terraform-Repo/module-project-practice/dev.tfvars
terraform apply -var-file=/home/azureuser/Terraform-Repo/module-project-practice/dev.tfvars

Screenshot Reference for the folder Structure