implement (un)managed volumes for aws, gcp and azure

Author: mboisson

aws/infrastructure.tf

@@ -130,7 +130,9 @@ resource "aws_instance" "instances" {
 }
 
 resource "aws_ebs_volume" "volumes" {
-  for_each          = module.design.volumes
+  for_each          = {
+    for x, values in module.design.volumes : x => values if lookup(values, "managed", true)
+  }
   availability_zone = local.availability_zone
   size              = each.value.size
   type              = lookup(each.value, "type", null)
@@ -140,6 +142,16 @@ resource "aws_ebs_volume" "volumes" {
     Name = "${var.cluster_name}-${each.key}"
   }
 }
+data "aws_ebs_volume" "existing_volumes" {
+  for_each = {
+    for x, values in module.design.volumes : x => values if ! lookup(values, "managed", true)
+  }
+
+  filter {
+    name   = "tag:Name"
+    values = ["${var.cluster_name}-${each.key}"]
+  }
+}
 
 locals {
   device_names = [
@@ -151,7 +163,7 @@ locals {
 resource "aws_volume_attachment" "attachments" {
   for_each     = module.design.volumes
   device_name  = local.device_names[index(module.design.volume_per_instance[each.value.instance], replace(each.key, "${each.value.instance}-", ""))]
-  volume_id    = aws_ebs_volume.volumes[each.key].id
+  volume_id    = try(aws_ebs_volume.volumes[each.key].id, aws_ebs_volume.existing_volumes[each.key].id)
   instance_id  = aws_instance.instances[each.value.instance].id
   skip_destroy = true
 }
@@ -175,7 +187,7 @@ locals {
           pv_key => {
             for name, specs in pv_values:
               name => merge(
-                { glob = "/dev/disk/by-id/*${replace(aws_ebs_volume.volumes["${x}-${pv_key}-${name}"].id, "-", "")}" },
+                { glob = try("/dev/disk/by-id/*${replace(aws_ebs_volume.volumes["${x}-${pv_key}-${name}"].id, "-", "")}", "/dev/disk/by-id/*${replace(aws_ebs_volume.existing_volumes["${x}-${pv_key}-${name}"].id, "-", "")}") },
                 specs,
               )
           } if contains(values.tags, pv_key)

azure/infrastructure.tf

@@ -128,18 +128,27 @@ resource "azurerm_linux_virtual_machine" "instances" {
 }
 
 resource "azurerm_managed_disk" "volumes" {
-  for_each             = module.design.volumes
+  for_each             = {
+    for x, values in module.design.volumes : x => values if lookup(values, "managed", true)
+  }
   name                 = format("%s-%s", var.cluster_name, each.key)
   location             = var.location
   resource_group_name  = local.resource_group_name
   storage_account_type = lookup(each.value, "type", "Premium_LRS")
   create_option        = "Empty"
   disk_size_gb         = each.value.size
 }
+data "azurerm_managed_disk" "existing_volumes" {
+  for_each             = {
+    for x, values in module.design.volumes : x => values if ! lookup(values, "managed", true)
+  }
+  name                 = format("%s-%s", var.cluster_name, each.key)
+  resource_group_name  = local.resource_group_name
+}
 
 resource "azurerm_virtual_machine_data_disk_attachment" "attachments" {
   for_each           = module.design.volumes
-  managed_disk_id    = azurerm_managed_disk.volumes[each.key].id
+  managed_disk_id    = try(azurerm_managed_disk.volumes[each.key].id, azurerm_managed_disk.existing_volumes[each.key].id)
   virtual_machine_id = azurerm_linux_virtual_machine.instances[each.value.instance].id
   lun                = index(module.design.volume_per_instance[each.value.instance], replace(each.key, "${each.value.instance}-", ""))
   caching            = "ReadWrite"

gcp/infrastructure.tf

@@ -143,17 +143,25 @@ resource "google_compute_instance" "instances" {
 }
 
 resource "google_compute_disk" "volumes" {
-  for_each = module.design.volumes
+  for_each = {
+    for x, values in module.design.volumes : x => values if lookup(values, "managed", true)
+  }
   name     = "${var.cluster_name}-${each.key}"
   type     = lookup(each.value, "type", "pd-standard")
   zone     = local.zone
   size     = each.value.size
 }
+data "google_compute_disk" "existing_volumes" {
+  for_each = {
+    for x, values in module.design.volumes : x => values if ! lookup(values, "managed", true)
+  }
+  name     = "${var.cluster_name}-${each.key}"
+}
 
 resource "google_compute_attached_disk" "attachments" {
   for_each    = module.design.volumes
-  disk        = google_compute_disk.volumes[each.key].self_link
-  device_name = google_compute_disk.volumes[each.key].name
+  disk        = try(google_compute_disk.volumes[each.key].self_link, google_compute_disk.existing_volumes[each.key].self_link)
+  device_name = try(google_compute_disk.volumes[each.key].name, google_compute_disk.existing_volumes[each.key].name)
   mode        = "READ_WRITE"
   instance    = google_compute_instance.instances[each.value.instance].self_link
 }