Creating Multiple Instances in Multiple Regions

Terraform
1

Hey all,

I’ve successfully set up a VPS creation+provisioning system where I can provision 3 VPS servers in one location:

resource "linode_instance" "LIN-SERVER" {
    count = 4
    region = "us-west"
    ...
}

However I’m running into issues when creating multiple instances in multiple regions, since using count and for_each in the same resource is not allowed:

resource "linode_instance" "LIN-SERVER" {
    # Deploy 4 VPS in each region
    count = 4
    for_each = toset([ "us-west", "us-central", "us-east" ])
    region = each.key
    ...
}

These resources are pretty big (lots variables and provision scripts), so I don’t want to simply duplicate this .tf for every region. I’d like to re-use code and keep things minimal as much as I can so this infrastructure is easier to maintain.

Can anyone please offer some advice on how to create multiple servers in multiple regions?

Thanks,
Mitch

2

I have come up with a solution so far using flatten[], but it seems like there should be an easier way to do this.

In the locals block I combine two arrays together and then flatten them to produce a single array.

Then, following this StackOverflow answer I can format region_list into region_list_formatted, which allows the se_region value to be accessed more easily in the resource block.

locals {
  region_list = flatten([
    for r in toset([ "us-west", "us-central", "us-east" ]) : [
      for i in toset([ 1, 2, 3, 4]) : {
        se_region = r
        unique_key = "${r}-${i}"
      }
    ]
  ])

  region_list_formatted = {
    for each in local.region_list : each.unique_key => { se_region = each.se_region }
  }
}

resource "linode_instance" "LIN-SESERVER" {  
    # Deploy 4 VPS in each region
    for_each = local.region_list_formatted 
    region = each.value.se_region
3

Another neat way is to define a module within the repo that creates everything for a single region (as there are usually various resources rather than just one). Then when you call the module you can use for_each to loop through the regions.

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