How to add availability zones to a for_each loop based on number of vms?

Terraform
1

So we take a variable such as var.node_name and allow the users to input as many node names to build out the vms using for_each. But now we have to add availability zones as an option, the regions we work in azure allow 1,2,3. We need to find a way to assign one zone per vm and if they create more than 3 vms to cycle through the numbers, if that makes sense.

variable "node_name" {}
variable "av_zones" {}

locals {
  name = split(",", var.node_name)
}

module "winvm_module" {
  for_each  = toset(local.name)
  source = "../modules/winvm_module"
  node_name = each.key
  av_zones = var.av_zones
}

I found this article “Using some loop with count and for_each. Availability zones and server count” that looks like I could use range maybe.

locals {
  # (I renamed the zones to letters so that they'd
  # be more distinct from the instance indices.)
  zones         = ["a", "b", "c"]
  instance_idxs = range(var.itemcount)

  instances = flatten([
    for z in local.zones : [
      for i in local.instance_idxs : {
        zone  = z
        index = i
      }
    ]
  ])
}

In the example here is there a way to get the range in var.node_names?

2

So I tried the for expression in the for_each loop with

instances = flatten([
    for n in local.name : [
    for z in local.av_zones : {
        name = n
        zone = z
      }
    ]
  ])

output "instances" {
  value = [ for n in local.instances : n ]
}

Though the output I’m getting is
instances = [
+ {
+ name = “Server01”
+ zone = 1
},
+ {
+ name = “Server01”
+ zone = 2
},
+ {
+ name = “Server01”
+ zone = 3
},
+ {
+ name = “Server02”
+ zone = 1
},
+ {
+ name = “Server02”
+ zone = 2
},
+ {
+ name = “Server02”
+ zone = 3
},

I guess what I really want is what I could get out of count with zones if I did something like this in the module.
zone = element(var.av_zones, (count.index))
However I want to try to use for_each so I’ll keep trying and post anything if I find an answer.

3

I ran into some luck and found a way to get this done.

instance = {for i, server_name in local.name : server_name => {
      node_name   = server_name
      zone        = element(var.av_zones, i)
    }
  }

Then
module “winvm_module” {
for_each = local.instance
source = “…/modules/winvm_module”
node_name = each.value.node_name
av_zones = [each.value.zone]
}

Hope this helps someone out trying to do the same or similar.

Source - https://stackoverflow.com/questions/62862887/terraform-looping-with-for-each