feat: Supports dynamic blocks in replication_specs

internal/convert/convert.go

@@ -37,7 +37,7 @@ const (
 )
 
 var (
-	dynamicBlockAllowList = []string{nTags, nLabels, nConfigSrc}
+	dynamicBlockAllowList = []string{nTags, nLabels, nConfigSrc, nRepSpecs}
 )
 
 type attrVals struct {
@@ -91,17 +91,22 @@ func convertResource(block *hclwrite.Block) (bool, error) {
 	}
 
 	var err error
-	if blockb.FirstMatchingBlock(nRepSpecs, nil) != nil {
-		err = fillCluster(blockb)
-	} else {
+	if isFreeTierCluster(blockb) {
 		err = fillFreeTierCluster(blockb)
+	} else {
+		err = fillCluster(blockb)
 	}
 	if err != nil {
 		return false, err
 	}
 	return true, nil
 }
 
+func isFreeTierCluster(resourceb *hclwrite.Body) bool {
+	d, _ := getDynamicBlock(resourceb, nRepSpecs)
+	return resourceb.FirstMatchingBlock(nRepSpecs, nil) == nil && !d.IsPresent()
+}
+
 func convertDataSource(block *hclwrite.Block) bool {
 	if block.Type() != dataSourceType {
 		return false
@@ -190,6 +195,15 @@ func fillCluster(resourceb *hclwrite.Body) error {
 }
 
 func fillReplicationSpecs(resourceb *hclwrite.Body, root attrVals) error {
+	d, err := fillReplicationSpecsWithDynamicBlock(resourceb, root)
+	if err != nil {
+		return err
+	}
+	if d.IsPresent() {
+		resourceb.RemoveBlock(d.block)
+		resourceb.SetAttributeRaw(nRepSpecs, d.tokens)
+		return nil
+	}
 	// at least one replication_specs exists here, if not it would be a free tier cluster
 	var specbs []*hclwrite.Body
 	for {
@@ -312,6 +326,15 @@ func fillBlockOpt(resourceb *hclwrite.Body, name string) {
 	resourceb.SetAttributeRaw(name, hcl.TokensObject(block.Body()))
 }
 
+// fillReplicationSpecsWithDynamicBlock used for dynamic blocks in replication_specs
+func fillReplicationSpecsWithDynamicBlock(resourceb *hclwrite.Body, root attrVals) (dynamicBlock, error) {
+	d, err := getDynamicBlock(resourceb, nRepSpecs)
+	if err != nil || !d.IsPresent() {
+		return dynamicBlock{}, err
+	}
+	return d, nil
+}
+
 // fillReplicationSpecsWithDynamicRegionConfigs is used for dynamic blocks in region_configs
 func fillReplicationSpecsWithDynamicRegionConfigs(specbSrc *hclwrite.Body, root attrVals) (dynamicBlock, error) {
 	d, err := getDynamicBlock(specbSrc, nConfigSrc)
@@ -414,7 +437,7 @@ func getSpecs(configSrc *hclwrite.Block, countName string, root attrVals, isDyna
 	}
 	tokens := hcl.TokensObject(fileb)
 	if isDynamicBlock {
-		tokens = encloseDynamicBlockRegionSpec(tokens, countName)
+		tokens = append(hcl.TokensFromExpr(fmt.Sprintf("%s.%s == 0 ? null :", nRegion, countName)), tokens...)
 	}
 	return tokens, nil
 }
@@ -520,12 +543,6 @@ func replaceDynamicBlockExpr(attr *hclwrite.Attribute, blockName, attrName strin
 	return strings.ReplaceAll(expr, fmt.Sprintf("%s.%s", blockName, attrName), attrName)
 }
 
-func encloseDynamicBlockRegionSpec(specTokens hclwrite.Tokens, countName string) hclwrite.Tokens {
-	tokens := hcl.TokensFromExpr(fmt.Sprintf("%s.%s > 0 ?", nRegion, countName))
-	tokens = append(tokens, specTokens...)
-	return append(tokens, hcl.TokensFromExpr(": null")...)
-}
-
 // getDynamicBlockRegionConfigsRegionArray returns the region array for a dynamic block in replication_specs.
 // e.g. [ for region in var.replication_specs.regions_config : { ... } if priority == region.priority ]
 func getDynamicBlockRegionConfigsRegionArray(d dynamicBlock, root attrVals) (hclwrite.Tokens, error) {

internal/convert/testdata/clu2adv/dynamic_regions_config_auto_scaling.out.tf

@@ -23,27 +23,27 @@ resource "mongodbatlas_advanced_cluster" "cluster" {
             provider_name = var.provider_name
             region_name   = region.region_name
             priority      = region.priority
-            electable_specs = region.electable_nodes > 0 ? {
+            electable_specs = region.electable_nodes == 0 ? null : {
               node_count      = region.electable_nodes
               instance_size   = var.provider_instance_size_name
               disk_size_gb    = var.disk_size_gb
               ebs_volume_type = var.provider_volume_type
               disk_iops       = var.provider_disk_iops
-            } : null
-            read_only_specs = region.read_only_nodes > 0 ? {
+            }
+            read_only_specs = region.read_only_nodes == 0 ? null : {
               node_count      = region.read_only_nodes
               instance_size   = var.provider_instance_size_name
               disk_size_gb    = var.disk_size_gb
               ebs_volume_type = var.provider_volume_type
               disk_iops       = var.provider_disk_iops
-            } : null
-            analytics_specs = region.analytics_nodes > 0 ? {
+            }
+            analytics_specs = region.analytics_nodes == 0 ? null : {
               node_count      = region.analytics_nodes
               instance_size   = var.provider_instance_size_name
               disk_size_gb    = var.disk_size_gb
               ebs_volume_type = var.provider_volume_type
               disk_iops       = var.provider_disk_iops
-            } : null
+            }
             auto_scaling = {
               disk_gb_enabled = var.auto_scaling_disk_gb_enabled
             }

internal/convert/testdata/clu2adv/dynamic_regions_config_basic.out.tf

@@ -12,14 +12,14 @@ resource "mongodbatlas_advanced_cluster" "dynamic_regions_config" {
             provider_name = "AWS"
             region_name   = region.region_name
             priority      = region.prio
-            electable_specs = region.electable_nodes > 0 ? {
+            electable_specs = region.electable_nodes == 0 ? null : {
               node_count    = region.electable_nodes
               instance_size = "M10"
-            } : null
-            read_only_specs = region.read_only_nodes > 0 ? {
+            }
+            read_only_specs = region.read_only_nodes == 0 ? null : {
               node_count    = region.read_only_nodes
               instance_size = "M10"
-            } : null
+            }
           } if priority == region.prio
         ]
       ])

internal/convert/testdata/clu2adv/dynamic_replication_specs.in.tf

@@ -0,0 +1,87 @@
+# Based on https://github.com/mongodb/terraform-provider-mongodbatlas/blob/master/examples/migrate_cluster_to_advanced_cluster/module_maintainer/v1/main.tf
+resource "mongodbatlas_cluster" "this" {
+  lifecycle {
+    precondition {
+      condition     = !(var.auto_scaling_disk_gb_enabled && var.disk_size > 0)
+      error_message = "Must use either auto_scaling_disk_gb_enabled or disk_size, not both."
+    }
+  }
+
+  project_id                   = var.project_id
+  name                         = var.cluster_name
+  auto_scaling_disk_gb_enabled = var.auto_scaling_disk_gb_enabled
+  cluster_type                 = var.cluster_type
+  disk_size_gb                 = var.disk_size
+  mongo_db_major_version       = var.mongo_db_major_version
+  provider_instance_size_name  = var.instance_size
+  provider_name                = var.provider_name
+
+  dynamic "tags" {
+    for_each = var.tags
+    content {
+      key   = tags.key
+      value = tags.value
+    }
+  }
+
+  dynamic "replication_specs" {
+    for_each = var.replication_specs
+    content {
+      num_shards = replication_specs.value.num_shards
+      zone_name  = replication_specs.value.zone_name
+
+      dynamic "regions_config" {
+        for_each = replication_specs.value.regions_config
+        content {
+          electable_nodes = regions_config.value.electable_nodes
+          priority        = regions_config.value.priority
+          read_only_nodes = regions_config.value.read_only_nodes
+          region_name     = regions_config.value.region_name
+        }
+      }
+    }
+  }
+}
+
+# example of variable for demostration purposes, not used in the conversion
+variable "replication_specs" {
+  description = "List of replication specifications in mongodbatlas_cluster format"
+  type = list(object({
+    num_shards = number
+    zone_name  = string
+    regions_config = list(object({
+      region_name     = string
+      electable_nodes = number
+      priority        = number
+      read_only_nodes = optional(number, 0)
+    }))
+  }))
+  default = [
+    {
+      num_shards = 1
+      zone_name  = "Zone 1"
+      regions_config = [
+        {
+          region_name     = "US_EAST_1"
+          electable_nodes = 3
+          priority        = 7
+        }
+      ]
+      }, {
+      num_shards = 2
+      zone_name  = "Zone 2"
+      regions_config = [
+        {
+          region_name     = "US_WEST_2"
+          electable_nodes = 2
+          priority        = 6
+          read_only_nodes = 1
+          }, {
+          region_name     = "EU_WEST_1"
+          electable_nodes = 3
+          priority        = 7
+        }
+      ]
+    }
+  ]
+}

internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf

@@ -0,0 +1,89 @@
+# Based on https://github.com/mongodb/terraform-provider-mongodbatlas/blob/master/examples/migrate_cluster_to_advanced_cluster/module_maintainer/v1/main.tf
+resource "mongodbatlas_advanced_cluster" "this" {
+  lifecycle {
+    precondition {
+      condition     = !(var.auto_scaling_disk_gb_enabled && var.disk_size > 0)
+      error_message = "Must use either auto_scaling_disk_gb_enabled or disk_size, not both."
+    }
+  }
+
+  project_id             = var.project_id
+  name                   = var.cluster_name
+  cluster_type           = var.cluster_type
+  mongo_db_major_version = var.mongo_db_major_version
+
+  replication_specs = flatten([
+    for spec in var.replication_specs : [
+      for i in range(var.replication_specs.num_shards) : {
+        zone_name = var.zone_name
+        region_configs = flatten([
+          # Regions must be sorted by priority in descending order.
+          for priority in range(7, 0, -1) : [
+            for region in var.replication_specs.regions_config : {
+              provider_name = var.provider_name
+              region_name   = region.region_name
+              priority      = region.priority
+              electable_specs = region.electable_nodes == 0 ? null : {
+                node_count    = region.electable_nodes
+                instance_size = var.instance_size
+                disk_size_gb  = var.disk_size
+              }
+              read_only_specs = region.read_only_nodes == 0 ? null : {
+                node_count    = region.read_only_nodes
+                instance_size = var.instance_size
+                disk_size_gb  = var.disk_size
+              }
+            } if priority == region.priority
+          ]
+        ])
+      }
+    ]
+  ])
+  tags = var.tags
+
+  # Generated by atlas-cli-plugin-terraform.
+  # Please review the changes and confirm that references to this resource are updated.
+}
+
+# example of variable for demostration purposes, not used in the conversion
+variable "replication_specs" {
+  description = "List of replication specifications in mongodbatlas_cluster format"
+  type = list(object({
+    num_shards = number
+    zone_name  = string
+    regions_config = list(object({
+      region_name     = string
+      electable_nodes = number
+      priority        = number
+      read_only_nodes = optional(number, 0)
+    }))
+  }))
+  default = [
+    {
+      num_shards = 1
+      zone_name  = "Zone 1"
+      regions_config = [
+        {
+          region_name     = "US_EAST_1"
+          electable_nodes = 3
+          priority        = 7
+        }
+      ]
+      }, {
+      num_shards = 2
+      zone_name  = "Zone 2"
+      regions_config = [
+        {
+          region_name     = "US_WEST_2"
+          electable_nodes = 2
+          priority        = 6
+          read_only_nodes = 1
+          }, {
+          region_name     = "EU_WEST_1"
+          electable_nodes = 3
+          priority        = 7
+        }
+      ]
+    }
+  ]
+}

internal/convert/testdata/clu2adv/errors.json

@@ -1,10 +1,9 @@
 {
+	"autoscaling_missing_attribute": "setting replication_specs: attribute provider_instance_size_name not found",
 	"configuration_file_error": "failed to parse Terraform config file",
 	"free_cluster_missing_attribute": "free cluster (because no replication_specs): attribute backing_provider_name not found",
-	"autoscaling_missing_attribute": "setting replication_specs: attribute provider_instance_size_name not found",
-	"replication_specs_missing_regions_config": "setting replication_specs: regions_config not found",
 	"regions_config_missing_priority": "setting replication_specs: attribute priority not found",
-	"replication_specs_unsupported_dynamic": "dynamic blocks are not supported",
-	"replication_specs_non_literal_num_shards": "setting num_shards: failed to evaluate number",
-	"replication_specs_missing_num_shards": "num_shards not found"
+	"replication_specs_missing_num_shards": "num_shards not found",
+	"replication_specs_missing_regions_config": "setting replication_specs: regions_config not found",
+	"replication_specs_non_literal_num_shards": "setting num_shards: failed to evaluate number"
 }