Terraform: Official Sleep Example

Description:

So the other day I was working on App Service in terraform and I kept having an issue with the App Service Slot Custom Hostname Binding resource where it would fail if you pass in multiple domains and hostnames and use count to iterate over them:

CreateOrUpdateHostNameBindingSlot: Failure responding to request: StatusCode=409 -- Original Error: autorest/azure: Service returned an error. Status=409 Code="Conflict" Message="Cannot modify this site because another operation is in progress

╷
│ Error: creating App Service Slot Custom Hostname Binding: (Host Name Binding Name "slot-1.a.example.com" / Slot Name "slot-1" / Site Name "my-app-service" / Resource Group "unittest-app-service"): web.AppsClient#CreateOrUpdateHostNameBindingSlot: Failure responding to request: StatusCode=409 -- Original Error: autorest/azure: Service returned an error. Status=409 Code="Conflict" Message="Cannot modify this site because another operation is in progress. Details: Id: 52866c8e-dabe-488d-95fe-503b3b75cb09, OperationName: Update, CreatedTime: 12/28/2022 8:57:50 PM, RequestId: b1b7ebc3-8882-4bd7-94bd-004da4056451, EntityType: 3" Details=[{"Message":"Cannot modify this site because another operation is in progress. Details: Id: 52866c8e-dabe-488d-95fe-503b3b75cb09, OperationName: Update, CreatedTime: 12/28/2022 8:57:50 PM, RequestId: b1b7ebc3-8882-4bd7-94bd-004da4056451, EntityType: 3"},{"Code":"Conflict"},{"ErrorEntity":{"Code":"Conflict","ExtendedCode":"59203","Message":"Cannot modify this site because another operation is in progress. Details: Id: 52866c8e-dabe-488d-95fe-503b3b75cb09, OperationName: Update, CreatedTime: 12/28/2022 8:57:50 PM, RequestId: b1b7ebc3-8882-4bd7-94bd-004da4056451, EntityType: 3","MessageTemplate":"Cannot modify this site because another operation is in progress. Details: {0}","Parameters":["Id: 52866c8e-dabe-488d-95fe-503b3b75cb09, OperationName: Update, CreatedTime: 12/28/2022 8:57:50 PM, RequestId: b1b7ebc3-8882-4bd7-94bd-004da4056451, EntityType: 3"]}}]
│ 
│   with module..azurerm_app_service_slot_custom_hostname_binding.main_private_slot[0],
│   on .terraform/modules/appsvcTst/custombinding_private_slot.tf line 94, in resource "azurerm_app_service_slot_custom_hostname_binding" "main_private_slot":
│   94: resource "azurerm_app_service_slot_custom_hostname_binding" "main_private_slot" {
│ 

To Resolve:

1. In my quest to resolve the issue I came across many links:

   • link
   • link
   • link
   • link

2. What finally fixed it was just passing the parallelism=1 flag to the terraform apply in the pipeline. By default, terraform does 10 iterations on each resource if you use count or for each, and, as far as I know, this is the only way to force it to do them sequentially. I have no background in ARM templates, but I found that the copy function or whatever has a mode property you can set to serial, I just need the same thing in Terraform for App Service.

3. Anyways, if you want to deploy resources sequentially (and not wait between iterations in a loop), this can be done using the time_sleep resource and there are many examples online. For example (all credit to pet2cattle.com) :

   # https://pet2cattle.com/2021/06/time-sleep-between-resources
   
   resource "helm_release" "ampa" {
   name       = "ampa"
   chart      = "/home/git/ampa/helm-ampa"
   timeout    = 600
   
   namespace = var.namespace
   }
   
   resource "time_sleep" "wait_for_ingress_alb" {
   create_duration = "300s"
   
   depends_on = [helm_release.ampa]
   }
   
   data "kubernetes_ingress" "web" {
   metadata {
      name      = "votacions-ampa"
      namespace = var.namespace
   }
   
   time_sleep = [time_sleep.wait_for_ingress_alb]
   }
   

   • First, you need to use the time provider and the time_sleep resource.
   • In your code you deploy resource1 first, then set time_sleep to have a dependency on resource1 using depends_on, then you declare resource2 or data1 with a depends_on to the time_sleep resource.
   • So it goes: resource1 => time_sleep => data1/resource2 in that order.