From 222a235c8c12b5fa3c1f9aa7b61daaf6f3bf332f Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 04:45:17 +0100
Subject: [PATCH 01/15] change condition to make it clearer

---
 internal/convert/convert.go                          |  8 +-------
 .../dynamic_regions_config_auto_scaling.out.tf       | 12 ++++++------
 .../clu2adv/dynamic_regions_config_basic.out.tf      |  8 ++++----
 3 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/internal/convert/convert.go b/internal/convert/convert.go
index 8482b2c..add25fd 100644
--- a/internal/convert/convert.go
+++ b/internal/convert/convert.go
@@ -414,7 +414,7 @@ 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 +520,6 @@ 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) {
diff --git a/internal/convert/testdata/clu2adv/dynamic_regions_config_auto_scaling.out.tf b/internal/convert/testdata/clu2adv/dynamic_regions_config_auto_scaling.out.tf
index 62bbd5f..2aba85d 100644
--- a/internal/convert/testdata/clu2adv/dynamic_regions_config_auto_scaling.out.tf
+++ b/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
             }
diff --git a/internal/convert/testdata/clu2adv/dynamic_regions_config_basic.out.tf b/internal/convert/testdata/clu2adv/dynamic_regions_config_basic.out.tf
index a2f1050..334f3f8 100644
--- a/internal/convert/testdata/clu2adv/dynamic_regions_config_basic.out.tf
+++ b/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
         ]
       ])

From 2fd47c267cdbb34b84cb72b1700358a85f05677a Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 05:07:22 +0100
Subject: [PATCH 02/15] failing test

---
 .../clu2adv/dynamic_replication_specs.in.tf   | 87 ++++++++++++++++++
 .../clu2adv/dynamic_replication_specs.out.tf  | 90 +++++++++++++++++++
 2 files changed, 177 insertions(+)
 create mode 100644 internal/convert/testdata/clu2adv/dynamic_replication_specs.in.tf
 create mode 100644 internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf

diff --git a/internal/convert/testdata/clu2adv/dynamic_replication_specs.in.tf b/internal/convert/testdata/clu2adv/dynamic_replication_specs.in.tf
new file mode 100644
index 0000000..b26d4aa
--- /dev/null
+++ b/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
+        }
+      ]
+    }
+  ]
+}
diff --git a/internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf b/internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf
new file mode 100644
index 0000000..0f5a43f
--- /dev/null
+++ b/internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf
@@ -0,0 +1,90 @@
+# 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" "dynamic_regions_config" {
+  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
+  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
+        }
+      ]
+    }
+  ]
+}

From 08116f2fad3656d9302e766348596baf61badd32 Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 05:25:32 +0100
Subject: [PATCH 03/15] all dynamic blocks in replication_specs

---
 internal/convert/convert.go                   | 13 ++++++---
 .../clu2adv/dynamic_replication_specs.out.tf  | 11 ++++---
 internal/convert/testdata/clu2adv/errors.json |  9 +++---
 ...eplication_specs_unsupported_dynamic.in.tf | 29 -------------------
 4 files changed, 18 insertions(+), 44 deletions(-)
 delete mode 100644 internal/convert/testdata/clu2adv/replication_specs_unsupported_dynamic.in.tf

diff --git a/internal/convert/convert.go b/internal/convert/convert.go
index add25fd..67e27d2 100644
--- a/internal/convert/convert.go
+++ b/internal/convert/convert.go
@@ -37,7 +37,7 @@ const (
 )
 
 var (
-	dynamicBlockAllowList = []string{nTags, nLabels, nConfigSrc}
+	dynamicBlockAllowList = []string{nTags, nLabels, nConfigSrc, nRepSpecs}
 )
 
 type attrVals struct {
@@ -91,10 +91,10 @@ 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
@@ -102,6 +102,11 @@ func convertResource(block *hclwrite.Block) (bool, error) {
 	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
diff --git a/internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf b/internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf
index 0f5a43f..8dd60ff 100644
--- a/internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf
+++ b/internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf
@@ -1,5 +1,5 @@
 # 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" "dynamic_regions_config" {
+resource "mongodbatlas_advanced_cluster" "this" {
   lifecycle {
     precondition {
       condition     = !(var.auto_scaling_disk_gb_enabled && var.disk_size > 0)
@@ -7,11 +7,10 @@ resource "mongodbatlas_advanced_cluster" "dynamic_regions_config" {
     }
   }
 
-  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
-  mongo_db_major_version       = var.mongo_db_major_version
+  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 : [
diff --git a/internal/convert/testdata/clu2adv/errors.json b/internal/convert/testdata/clu2adv/errors.json
index fc81442..67fa980 100644
--- a/internal/convert/testdata/clu2adv/errors.json
+++ b/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"
 }
diff --git a/internal/convert/testdata/clu2adv/replication_specs_unsupported_dynamic.in.tf b/internal/convert/testdata/clu2adv/replication_specs_unsupported_dynamic.in.tf
deleted file mode 100644
index c2680bc..0000000
--- a/internal/convert/testdata/clu2adv/replication_specs_unsupported_dynamic.in.tf
+++ /dev/null
@@ -1,29 +0,0 @@
-
-resource "mongodbatlas_cluster" "geo" {
-  project_id                  = var.project_id
-  name                        = "geo"
-  cluster_type                = "GEOSHARDED"
-  num_shards                  = 1
-  provider_name               = "AWS"
-  provider_instance_size_name = "M30"
-
-  dynamic "replication_specs" {
-    for_each = {
-      "Zone 1" = {
-        region_name = "US_EAST_1"
-      },
-      "Zone 2" = {
-        region_name = "US_WEST_2"
-      }
-    }
-    content {
-      zone_name  = replication_specs.key
-      num_shards = 2
-      regions_config {
-        region_name     = replication_specs.value.region_name
-        electable_nodes = 3
-        priority        = 7
-      }
-    }
-  }
-}

From ab8633256abb925a1ec8dc606c3ee7fea4ae491f Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 05:46:16 +0100
Subject: [PATCH 04/15] initial fillReplicationSpecsWithDynamicBlock

---
 internal/convert/convert.go | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/internal/convert/convert.go b/internal/convert/convert.go
index 67e27d2..3066546 100644
--- a/internal/convert/convert.go
+++ b/internal/convert/convert.go
@@ -195,6 +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 {
@@ -317,6 +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)

From dbde632ca9431ce18e36def9d515403f7abfccf3 Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 07:02:46 +0100
Subject: [PATCH 05/15] pass tests

---
 internal/convert/const_names.go               |  1 +
 internal/convert/convert.go                   | 50 ++++++++++++-------
 .../clu2adv/dynamic_replication_specs.out.tf  | 10 ++--
 3 files changed, 41 insertions(+), 20 deletions(-)

diff --git a/internal/convert/const_names.go b/internal/convert/const_names.go
index c2adc20..8696bcc 100644
--- a/internal/convert/const_names.go
+++ b/internal/convert/const_names.go
@@ -55,4 +55,5 @@ const (
 	nForEach                    = "for_each"
 	nContent                    = "content"
 	nRegion                     = "region"
+	nSpec                       = "spec"
 )
diff --git a/internal/convert/convert.go b/internal/convert/convert.go
index 3066546..58f4fef 100644
--- a/internal/convert/convert.go
+++ b/internal/convert/convert.go
@@ -216,7 +216,7 @@ func fillReplicationSpecs(resourceb *hclwrite.Body, root attrVals) error {
 			break
 		}
 		specbSrc := specSrc.Body()
-		d, err := fillReplicationSpecsWithDynamicRegionConfigs(specbSrc, root)
+		d, err := fillReplicationSpecsWithDynamicRegionConfigs(specbSrc, root, false)
 		if err != nil {
 			return err
 		}
@@ -328,15 +328,24 @@ func fillBlockOpt(resourceb *hclwrite.Body, name string) {
 
 // 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() {
+	dSpec, err := getDynamicBlock(resourceb, nRepSpecs)
+	if err != nil || !dSpec.IsPresent() {
 		return dynamicBlock{}, err
 	}
-	return d, nil
+	transformDynamicBlockReferences(dSpec.content.Body(), nRepSpecs, nSpec)
+	dConfig, err := fillReplicationSpecsWithDynamicRegionConfigs(dSpec.content.Body(), root, true)
+	if err != nil {
+		return dynamicBlock{}, err
+	}
+	forSpec := hcl.TokensFromExpr(fmt.Sprintf("for %s in %s : ", nSpec, hcl.GetAttrExpr(dSpec.forEach)))
+	forSpec = append(forSpec, dConfig.tokens...)
+	tokens := hcl.TokensFuncFlatten(forSpec)
+	dSpec.tokens = tokens
+	return dSpec, nil
 }
 
 // fillReplicationSpecsWithDynamicRegionConfigs is used for dynamic blocks in region_configs
-func fillReplicationSpecsWithDynamicRegionConfigs(specbSrc *hclwrite.Body, root attrVals) (dynamicBlock, error) {
+func fillReplicationSpecsWithDynamicRegionConfigs(specbSrc *hclwrite.Body, root attrVals, transformRegionReferences bool) (dynamicBlock, error) {
 	d, err := getDynamicBlock(specbSrc, nConfigSrc)
 	if err != nil || !d.IsPresent() {
 		return dynamicBlock{}, err
@@ -346,7 +355,11 @@ func fillReplicationSpecsWithDynamicRegionConfigs(specbSrc *hclwrite.Body, root
 	if zoneName := hcl.GetAttrExpr(specbSrc.GetAttribute(nZoneName)); zoneName != "" {
 		repSpecb.SetAttributeRaw(nZoneName, hcl.TokensFromExpr(zoneName))
 	}
-	regionFor, err := getDynamicBlockRegionConfigsRegionArray(d, root)
+	forEach := hcl.GetAttrExpr(d.forEach)
+	if transformRegionReferences {
+		forEach = replaceDynamicBlockReferences(forEach, nRepSpecs, nSpec)
+	}
+	regionFor, err := getDynamicBlockRegionConfigsRegionArray(forEach, d.content, root)
 	if err != nil {
 		return dynamicBlock{}, err
 	}
@@ -545,33 +558,36 @@ func replaceDynamicBlockExpr(attr *hclwrite.Attribute, blockName, attrName strin
 
 // 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) {
-	transformDynamicBlockReferences(d.content.Body())
-	priorityStr := hcl.GetAttrExpr(d.content.Body().GetAttribute(nPriority))
+func getDynamicBlockRegionConfigsRegionArray(forEach string, configSrc *hclwrite.Block, root attrVals) (hclwrite.Tokens, error) {
+	transformDynamicBlockReferences(configSrc.Body(), nConfigSrc, nRegion)
+	priorityStr := hcl.GetAttrExpr(configSrc.Body().GetAttribute(nPriority))
 	if priorityStr == "" {
 		return nil, fmt.Errorf("%s: %s not found", errRepSpecs, nPriority)
 	}
-	region, err := getRegionConfig(d.content, root, true)
+	region, err := getRegionConfig(configSrc, root, true)
 	if err != nil {
 		return nil, err
 	}
-	tokens := hcl.TokensFromExpr(fmt.Sprintf("for %s in %s :", nRegion, hcl.GetAttrExpr(d.forEach)))
+	tokens := hcl.TokensFromExpr(fmt.Sprintf("for %s in %s :", nRegion, forEach))
 	tokens = append(tokens, hcl.EncloseBraces(region.BuildTokens(nil), true)...)
 	tokens = append(tokens, hcl.TokensFromExpr(fmt.Sprintf("if %s == %s", nPriority, priorityStr))...)
 	return hcl.EncloseBracketsNewLines(tokens), nil
 }
 
-// transformDynamicBlockReferences changes value references in all attributes, e.g. regions_config.value.electable_nodes to region.electable_nodes
-func transformDynamicBlockReferences(configSrcb *hclwrite.Body) {
+func transformDynamicBlockReferences(configSrcb *hclwrite.Body, blockName, varName string) {
 	for name, attr := range configSrcb.Attributes() {
-		expr := hcl.GetAttrExpr(attr)
-		expr = strings.ReplaceAll(expr,
-			fmt.Sprintf("%s.%s.", nConfigSrc, nValue),
-			fmt.Sprintf("%s.", nRegion))
+		expr := replaceDynamicBlockReferences(hcl.GetAttrExpr(attr), blockName, varName)
 		configSrcb.SetAttributeRaw(name, hcl.TokensFromExpr(expr))
 	}
 }
 
+// replaceDynamicBlockReferences changes value references, e.g. regions_config.value.electable_nodes to region.electable_nodes
+func replaceDynamicBlockReferences(expr, blockName, varName string) string {
+	return strings.ReplaceAll(expr,
+		fmt.Sprintf("%s.%s.", blockName, nValue),
+		fmt.Sprintf("%s.", varName))
+}
+
 func sortConfigsByPriority(configs []*hclwrite.Body) []*hclwrite.Body {
 	for _, config := range configs {
 		if _, err := hcl.GetAttrInt(config.GetAttribute(nPriority), errPriority); err != nil {
diff --git a/internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf b/internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf
index 8dd60ff..60549a3 100644
--- a/internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf
+++ b/internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf
@@ -12,14 +12,15 @@ resource "mongodbatlas_advanced_cluster" "this" {
   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
+      for i in range(spec.num_shards) : {
+        zone_name = spec.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 : {
+            for region in spec.regions_config : {
               provider_name = var.provider_name
               region_name   = region.region_name
               priority      = region.priority
@@ -33,6 +34,9 @@ resource "mongodbatlas_advanced_cluster" "this" {
                 instance_size = var.instance_size
                 disk_size_gb  = var.disk_size
               }
+              auto_scaling = {
+                disk_gb_enabled = var.auto_scaling_disk_gb_enabled
+              }
             } if priority == region.priority
           ]
         ])

From 4bd2d11f42ddf7eb234567ca3143bb11f36e1e61 Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 07:04:20 +0100
Subject: [PATCH 06/15] rename test

---
 ...lication_specs.in.tf => dynamic_replication_specs_basic.in.tf} | 0
 ...cation_specs.out.tf => dynamic_replication_specs_basic.out.tf} | 0
 2 files changed, 0 insertions(+), 0 deletions(-)
 rename internal/convert/testdata/clu2adv/{dynamic_replication_specs.in.tf => dynamic_replication_specs_basic.in.tf} (100%)
 rename internal/convert/testdata/clu2adv/{dynamic_replication_specs.out.tf => dynamic_replication_specs_basic.out.tf} (100%)

diff --git a/internal/convert/testdata/clu2adv/dynamic_replication_specs.in.tf b/internal/convert/testdata/clu2adv/dynamic_replication_specs_basic.in.tf
similarity index 100%
rename from internal/convert/testdata/clu2adv/dynamic_replication_specs.in.tf
rename to internal/convert/testdata/clu2adv/dynamic_replication_specs_basic.in.tf
diff --git a/internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf b/internal/convert/testdata/clu2adv/dynamic_replication_specs_basic.out.tf
similarity index 100%
rename from internal/convert/testdata/clu2adv/dynamic_replication_specs.out.tf
rename to internal/convert/testdata/clu2adv/dynamic_replication_specs_basic.out.tf

From 06b3f32a13fd826d1d3465b2e8e0e9d92943175f Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 07:18:04 +0100
Subject: [PATCH 07/15] test with different var names

---
 internal/convert/convert.go                   |  2 +-
 ...replication_specs_different_var_name.in.tf | 45 ++++++++++++++
 ...eplication_specs_different_var_name.out.tf | 58 +++++++++++++++++++
 3 files changed, 104 insertions(+), 1 deletion(-)
 create mode 100644 internal/convert/testdata/clu2adv/dynamic_replication_specs_different_var_name.in.tf
 create mode 100644 internal/convert/testdata/clu2adv/dynamic_replication_specs_different_var_name.out.tf

diff --git a/internal/convert/convert.go b/internal/convert/convert.go
index 58f4fef..23b2d32 100644
--- a/internal/convert/convert.go
+++ b/internal/convert/convert.go
@@ -450,7 +450,7 @@ func getSpecs(configSrc *hclwrite.Block, countName string, root attrVals, isDyna
 	}
 	tokens := hcl.TokensObject(fileb)
 	if isDynamicBlock {
-		tokens = append(hcl.TokensFromExpr(fmt.Sprintf("%s.%s == 0 ? null :", nRegion, countName)), tokens...)
+		tokens = append(hcl.TokensFromExpr(fmt.Sprintf("%s == 0 ? null :", hcl.GetAttrExpr(count))), tokens...)
 	}
 	return tokens, nil
 }
diff --git a/internal/convert/testdata/clu2adv/dynamic_replication_specs_different_var_name.in.tf b/internal/convert/testdata/clu2adv/dynamic_replication_specs_different_var_name.in.tf
new file mode 100644
index 0000000..ead726f
--- /dev/null
+++ b/internal/convert/testdata/clu2adv/dynamic_replication_specs_different_var_name.in.tf
@@ -0,0 +1,45 @@
+resource "mongodbatlas_cluster" "different_var_names" {
+  project_id                  = var.project_id
+  name                        = var.cluster_name
+  cluster_type                = var.cluster_type
+  provider_instance_size_name = var.instance_size
+  provider_name               = var.provider_name
+  dynamic "replication_specs" {
+    for_each = var.my_rep_specs
+    content {
+      num_shards = replication_specs.value.my_shards
+      zone_name  = replication_specs.value.my_zone
+
+      dynamic "regions_config" {
+        for_each = replication_specs.value.my_regions
+        content {
+          electable_nodes = regions_config.value.my_electable_nodes
+          priority        = regions_config.value.prio
+          region_name     = regions_config.value.my_region_name
+        }
+      }
+    }
+  }
+}
+
+resource "mongodbatlas_cluster" "different_var_names_no_zone_name" {
+  project_id                  = var.project_id
+  name                        = var.cluster_name
+  cluster_type                = var.cluster_type
+  provider_instance_size_name = var.instance_size
+  provider_name               = var.provider_name
+  dynamic "replication_specs" {
+    for_each = var.my_rep_specs
+    content {
+      num_shards = replication_specs.value.my_shards
+      dynamic "regions_config" {
+        for_each = replication_specs.value.my_regions
+        content {
+          electable_nodes = regions_config.value.my_electable_nodes
+          priority        = regions_config.value.prio
+          region_name     = regions_config.value.my_region_name
+        }
+      }
+    }
+  }
+}
diff --git a/internal/convert/testdata/clu2adv/dynamic_replication_specs_different_var_name.out.tf b/internal/convert/testdata/clu2adv/dynamic_replication_specs_different_var_name.out.tf
new file mode 100644
index 0000000..f680357
--- /dev/null
+++ b/internal/convert/testdata/clu2adv/dynamic_replication_specs_different_var_name.out.tf
@@ -0,0 +1,58 @@
+resource "mongodbatlas_advanced_cluster" "different_var_names" {
+  project_id   = var.project_id
+  name         = var.cluster_name
+  cluster_type = var.cluster_type
+  replication_specs = flatten([
+    for spec in var.my_rep_specs : [
+      for i in range(spec.my_shards) : {
+        zone_name = spec.my_zone
+        region_configs = flatten([
+          # Regions must be sorted by priority in descending order.
+          for priority in range(7, 0, -1) : [
+            for region in spec.my_regions : {
+              provider_name = var.provider_name
+              region_name   = region.my_region_name
+              priority      = region.prio
+              electable_specs = region.my_electable_nodes == 0 ? null : {
+                node_count    = region.my_electable_nodes
+                instance_size = var.instance_size
+              }
+            } if priority == region.prio
+          ]
+        ])
+      }
+    ]
+  ])
+
+  # Generated by atlas-cli-plugin-terraform.
+  # Please review the changes and confirm that references to this resource are updated.
+}
+
+resource "mongodbatlas_advanced_cluster" "different_var_names_no_zone_name" {
+  project_id   = var.project_id
+  name         = var.cluster_name
+  cluster_type = var.cluster_type
+  replication_specs = flatten([
+    for spec in var.my_rep_specs : [
+      for i in range(spec.my_shards) : {
+        region_configs = flatten([
+          # Regions must be sorted by priority in descending order.
+          for priority in range(7, 0, -1) : [
+            for region in spec.my_regions : {
+              provider_name = var.provider_name
+              region_name   = region.my_region_name
+              priority      = region.prio
+              electable_specs = region.my_electable_nodes == 0 ? null : {
+                node_count    = region.my_electable_nodes
+                instance_size = var.instance_size
+              }
+            } if priority == region.prio
+          ]
+        ])
+      }
+    ]
+  ])
+
+  # Generated by atlas-cli-plugin-terraform.
+  # Please review the changes and confirm that references to this resource are updated.
+}

From 204b118cf000951d7b8f0ca5ddcc9115c0d89ff3 Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 07:27:34 +0100
Subject: [PATCH 08/15] doc

---
 CHANGELOG.md |  2 +-
 README.md    | 45 ++++++++++++++++++++++++++++++++++-----------
 2 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6d6920c..ccec360 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,7 @@
 
 ENHANCEMENTS:
 
-* Supports `dynamic` block for `tags`, `labels` and `regions_config`
+* Supports `dynamic` blocks for `tags`, `labels`, `regions_config` and `replication_specs`
 
 ## 1.0.0 (Mar 6, 2025)
 
diff --git a/README.md b/README.md
index 69fd104..faf1c1a 100644
--- a/README.md
+++ b/README.md
@@ -78,28 +78,51 @@ dynamic "tags" {
 You can use `dynamic` blocks for `regions_config`. The plugin assumes that `for_each` has an expression which is evaluated to a `list` or `set` of objects.
 This is an example of how to use dynamic blocks in `regions_config`:
 ```hcl
-  replication_specs {
-    num_shards = var.replication_specs.num_shards
-    zone_name  = var.replication_specs.zone_name # only needed if you're using zones
+replication_specs {
+  num_shards = var.replication_specs.num_shards
+  zone_name  = var.replication_specs.zone_name # only needed if you're using zones
+  dynamic "regions_config" {
+    for_each = var.replication_specs.regions_config
+    content {
+      priority        = regions_config.value.priority
+      region_name     = regions_config.value.region_name
+      electable_nodes = regions_config.value.electable_nodes
+      read_only_nodes = regions_config.value.read_only_nodes
+    }
+  }
+}
+```
+Dynamic block and individual blocks for `regions_config` are not supported at the same time. If you need this use case, please send us [feedback](https://github.com/mongodb-labs/atlas-cli-plugin-terraform/issues). There are currently two main approaches to handle this:
+- (Recommended) Remove the individual `regions_config` blocks and add their information to the variable you're using in the `for_each` expression, e.g. using [concat](https://developer.hashicorp.com/terraform/language/functions/concat) if you're using a list or [setunion](https://developer.hashicorp.com/terraform/language/functions/setunion) for sets. In this way, you don't need to change the generated `mongodb_advanced_cluster` configuration.
+- Change the generated `mongodb_advanced_cluster` configuration to join the individual blocks to the code generated for the `dynamic` block. This approach is more error-prone.
+
+#### Dynamic blocks in replication_specs
+
+You can use `dynamic` blocks for `replication_specs`. The plugin assumes that `for_each` has an expression which is evaluated to a `list` of objects.
+This is an example of how to use dynamic blocks in `replication_specs`:
+```hcl
+dynamic "replication_specs" {
+  for_each = var.replication_specs
+  content {
+    num_shards = replication_specs.value.num_shards
+    zone_name  = replication_specs.value.zone_name # only needed if you're using zones
     dynamic "regions_config" {
-      for_each = var.replication_specs.regions_config
+      for_each = replication_specs.value.regions_config
       content {
-        priority        = regions_config.value.priority
-        region_name     = regions_config.value.region_name
         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
       }
     }
   }
-```
-Dynamic block and individual blocks for `regions_config` are not supported at the same time. If you need this use case, please send us [feedback](https://github.com/mongodb-labs/atlas-cli-plugin-terraform/issues). There are currently two main approaches to handle this:
-- (Recommended) Remove the individual `regions_config` blocks and add their information to the variable you're using in the `for_each` expression, e.g. using [concat](https://developer.hashicorp.com/terraform/language/functions/concat) if you're using a list or [setunion](https://developer.hashicorp.com/terraform/language/functions/setunion) for sets. In this way, you don't need to change the generated `mongodb_advanced_cluster` configuration.
-- Change the generated `mongodb_advanced_cluster` configuration to join the individual blocks to the code generated for the `dynamic` block. This approach is more error-prone.
+}
+Dynamic block and individual blocks for `replication_specs` are not supported at the same time. If you need this use case, please send us [feedback](https://github.com/mongodb-labs/atlas-cli-plugin-terraform/issues). You can handle this following the same approaches as for [`regions_config`](#dynamic-blocks-in-regions_config).
 
 ### Limitations
 
 - [`num_shards`](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/resources/cluster#num_shards-2) in `replication_specs` must be a numeric [literal expression](https://developer.hashicorp.com/nomad/docs/job-specification/hcl2/expressions#literal-expressions), e.g. `var.num_shards` is not supported. This is to allow creating a `replication_specs` element per shard in `mongodbatlas_advanced_cluster`. This limitation doesn't apply if you're using `dynamic` blocks in `regions_config` or `replication_specs`.
-- `dynamic` blocks are currently supported only for `tags`, `labels` and `regions_config`. See limitations for `regions_config` support in [its section](#dynamic-blocks-in-regions_config) above. **Coming soon**: support for `replication_specs`.
+- `dynamic` blocks are supported for `tags`, `labels`, `regions_config` and `replication_specs`. See limitations for [`regions_config`](#dynamic-blocks-in-regions_config) and [`replication_specs`](#dynamic-blocks-in-replication_specs) in their sections above.
 
 ## Feedback
 

From bd78ea884def7c9b1fdb2ae494192c22be6b201d Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 07:32:38 +0100
Subject: [PATCH 09/15] typo

---
 README.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/README.md b/README.md
index faf1c1a..62358da 100644
--- a/README.md
+++ b/README.md
@@ -117,6 +117,7 @@ dynamic "replication_specs" {
     }
   }
 }
+```
 Dynamic block and individual blocks for `replication_specs` are not supported at the same time. If you need this use case, please send us [feedback](https://github.com/mongodb-labs/atlas-cli-plugin-terraform/issues). You can handle this following the same approaches as for [`regions_config`](#dynamic-blocks-in-regions_config).
 
 ### Limitations

From 24737a0e00124d6bfbc494c96aaf2e749ef8d83d Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 07:51:00 +0100
Subject: [PATCH 10/15] reference to guide

---
 README.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/README.md b/README.md
index 62358da..e2c62d7 100644
--- a/README.md
+++ b/README.md
@@ -30,6 +30,8 @@ atlas plugin list
 
 ### Usage
 
+You can find more information in the [Migration Guide: Cluster to Advanced Cluster](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/guides/cluster-to-advanced-cluster-migration-guide).
+
 **Note**: In order to use the **Preview for MongoDB Atlas Provider 2.0.0** of `mongodbatlas_advanced_cluster`, you need to set the environment variable `MONGODB_ATLAS_PREVIEW_PROVIDER_V2_ADVANCED_CLUSTER` to `true`.
 
 If you want to convert a Terraform configuration from `mongodbatlas_cluster` to `mongodbatlas_advanced_cluster`, use the following command:

From 0c13a4abb84df4a50d274b7a3a5c44583dc21a1b Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 08:07:30 +0100
Subject: [PATCH 11/15] Update README.md

Co-authored-by: Marco Suma <smumrc@gmail.com>
---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index e2c62d7..766ebbf 100644
--- a/README.md
+++ b/README.md
@@ -125,7 +125,7 @@ Dynamic block and individual blocks for `replication_specs` are not supported at
 ### Limitations
 
 - [`num_shards`](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/resources/cluster#num_shards-2) in `replication_specs` must be a numeric [literal expression](https://developer.hashicorp.com/nomad/docs/job-specification/hcl2/expressions#literal-expressions), e.g. `var.num_shards` is not supported. This is to allow creating a `replication_specs` element per shard in `mongodbatlas_advanced_cluster`. This limitation doesn't apply if you're using `dynamic` blocks in `regions_config` or `replication_specs`.
-- `dynamic` blocks are supported for `tags`, `labels`, `regions_config` and `replication_specs`. See limitations for [`regions_config`](#dynamic-blocks-in-regions_config) and [`replication_specs`](#dynamic-blocks-in-replication_specs) in their sections above.
+- `dynamic` blocks are supported with some limitations for [`regions_config`](#dynamic-blocks-in-regions_config) and [`replication_specs`](#dynamic-blocks-in-replication_specs).
 
 ## Feedback
 

From e04dead0aac57ac21603fd423ea7bbc74569a283 Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 08:09:20 +0100
Subject: [PATCH 12/15] remove error-prone sentence

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 766ebbf..d746b79 100644
--- a/README.md
+++ b/README.md
@@ -96,7 +96,7 @@ replication_specs {
 ```
 Dynamic block and individual blocks for `regions_config` are not supported at the same time. If you need this use case, please send us [feedback](https://github.com/mongodb-labs/atlas-cli-plugin-terraform/issues). There are currently two main approaches to handle this:
 - (Recommended) Remove the individual `regions_config` blocks and add their information to the variable you're using in the `for_each` expression, e.g. using [concat](https://developer.hashicorp.com/terraform/language/functions/concat) if you're using a list or [setunion](https://developer.hashicorp.com/terraform/language/functions/setunion) for sets. In this way, you don't need to change the generated `mongodb_advanced_cluster` configuration.
-- Change the generated `mongodb_advanced_cluster` configuration to join the individual blocks to the code generated for the `dynamic` block. This approach is more error-prone.
+- Change the generated `mongodb_advanced_cluster` configuration to join the individual blocks to the code generated for the `dynamic` block.
 
 #### Dynamic blocks in replication_specs
 

From 919fc02630c397f0dc9c3c125a392133b4c346e0 Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 15:17:01 +0100
Subject: [PATCH 13/15] add guide

---
 README.md                           | 10 +--
 docs/guide_clu2adv_dynamic_block.md | 98 +++++++++++++++++++++++++++++
 2 files changed, 101 insertions(+), 7 deletions(-)
 create mode 100644 docs/guide_clu2adv_dynamic_block.md

diff --git a/README.md b/README.md
index d746b79..eb3839c 100644
--- a/README.md
+++ b/README.md
@@ -77,7 +77,7 @@ dynamic "tags" {
 
 #### Dynamic blocks in regions_config
 
-You can use `dynamic` blocks for `regions_config`. The plugin assumes that `for_each` has an expression which is evaluated to a `list` or `set` of objects.
+You can use `dynamic` blocks for `regions_config`. The plugin assumes that `for_each` has an expression which is evaluated to a `list` or `set` of objects. See this [guide](./docs/guide_clu2adv_dynamic_block.md) to learn more about some limitations.
 This is an example of how to use dynamic blocks in `regions_config`:
 ```hcl
 replication_specs {
@@ -94,13 +94,10 @@ replication_specs {
   }
 }
 ```
-Dynamic block and individual blocks for `regions_config` are not supported at the same time. If you need this use case, please send us [feedback](https://github.com/mongodb-labs/atlas-cli-plugin-terraform/issues). There are currently two main approaches to handle this:
-- (Recommended) Remove the individual `regions_config` blocks and add their information to the variable you're using in the `for_each` expression, e.g. using [concat](https://developer.hashicorp.com/terraform/language/functions/concat) if you're using a list or [setunion](https://developer.hashicorp.com/terraform/language/functions/setunion) for sets. In this way, you don't need to change the generated `mongodb_advanced_cluster` configuration.
-- Change the generated `mongodb_advanced_cluster` configuration to join the individual blocks to the code generated for the `dynamic` block.
 
 #### Dynamic blocks in replication_specs
 
-You can use `dynamic` blocks for `replication_specs`. The plugin assumes that `for_each` has an expression which is evaluated to a `list` of objects.
+You can use `dynamic` blocks for `replication_specs`. The plugin assumes that `for_each` has an expression which is evaluated to a `list` of objects. See this [guide](./docs/guide_clu2adv_dynamic_block.md) to learn more about some limitations.
 This is an example of how to use dynamic blocks in `replication_specs`:
 ```hcl
 dynamic "replication_specs" {
@@ -120,12 +117,11 @@ dynamic "replication_specs" {
   }
 }
 ```
-Dynamic block and individual blocks for `replication_specs` are not supported at the same time. If you need this use case, please send us [feedback](https://github.com/mongodb-labs/atlas-cli-plugin-terraform/issues). You can handle this following the same approaches as for [`regions_config`](#dynamic-blocks-in-regions_config).
 
 ### Limitations
 
 - [`num_shards`](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/resources/cluster#num_shards-2) in `replication_specs` must be a numeric [literal expression](https://developer.hashicorp.com/nomad/docs/job-specification/hcl2/expressions#literal-expressions), e.g. `var.num_shards` is not supported. This is to allow creating a `replication_specs` element per shard in `mongodbatlas_advanced_cluster`. This limitation doesn't apply if you're using `dynamic` blocks in `regions_config` or `replication_specs`.
-- `dynamic` blocks are supported with some limitations for [`regions_config`](#dynamic-blocks-in-regions_config) and [`replication_specs`](#dynamic-blocks-in-replication_specs).
+- `dynamic` blocks are supported with some [limitations](./docs/guide_clu2adv_dynamic_block.md).
 
 ## Feedback
 
diff --git a/docs/guide_clu2adv_dynamic_block.md b/docs/guide_clu2adv_dynamic_block.md
new file mode 100644
index 0000000..37933e4
--- /dev/null
+++ b/docs/guide_clu2adv_dynamic_block.md
@@ -0,0 +1,98 @@
+# Guide to handle dynamic block limitations in regions_config and replication_specs
+
+The plugin command to convert `mongodbatlas_cluster` resources to `mongodbatlas_advanced_cluster` supports `dynamic` blocks for `regions_config` and `replication_specs`. However, there are some limitations when using `dynamic` blocks in these fields. This guide explains how to handle these limitations.
+
+If you need to use the plugin for use cases not yet supported, please send us [feedback](https://github.com/mongodb-labs/atlas-cli-plugin-terraform/issues).
+
+## Dynamic block and individual blocks in the same resource
+
+Dynamic block and individual blocks for `regions_config` are not supported at the same time. The recommended way to handle this is to remove the individual `regions_config` or `replication_specs` blocks and use a local variable to add the individual block information to the variable you're using in the `for_each` expression, using [concat](https://developer.hashicorp.com/terraform/language/functions/concat) if you're using a list or [setunion](https://developer.hashicorp.com/terraform/language/functions/setunion) for sets.
+
+Let's see an example with `regions_config`, it is the same for `replication_specs`. In the original configuration file, the `mongodb_cluster` resource is used inside a module that receives the `regions_config` elements in a `list` variable and we want to add an additional `region_config` with a read-only node.
+```hcl
+variable "replication_specs" {
+  type = object({
+    num_shards = number
+    regions_config = list(object({
+      region_name     = string
+      electable_nodes = number
+      priority        = number
+      read_only_nodes = number
+    }))
+  })
+}
+
+resource "mongodbatlas_cluster" "this" {
+  project_id                  = var.project_id
+  name                        = var.cluster_name
+  cluster_type                = var.cluster_type
+  provider_name               = var.provider_name
+  provider_instance_size_name = var.provider_instance_size_name
+  replication_specs {
+    num_shards = var.replication_specs.num_shards
+    dynamic "regions_config" {
+      for_each = var.replication_specs.regions_config
+      content {
+        region_name     = regions_config.value.region_name
+        electable_nodes = regions_config.value.electable_nodes
+        priority        = regions_config.value.priority
+        read_only_nodes = regions_config.value.read_only_nodes
+      }
+    }
+    regions_config { # individual region
+      region_name     = "US_EAST_1"
+      read_only_nodes = 1
+    }
+  }
+}
+```
+
+We modify the configuration file to create an intermediate `local` variable to merge the `regions_config` variable elements and the additional `region_config`:
+```hcl
+variable "replication_specs" {
+  type = object({
+    num_shards = number
+    regions_config = list(object({
+      region_name     = string
+      electable_nodes = number
+      priority        = number
+      read_only_nodes = number
+    }))
+  })
+}
+
+locals {
+  regions_config_all = concat(
+    var.replication_specs.regions_config,
+    [
+      {
+        region_name     = "US_EAST_1"
+        electable_nodes = 0
+        priority        = 0
+        read_only_nodes = 1
+      },
+    ]
+  )
+}
+
+resource "mongodbatlas_cluster" "this" {
+  project_id                  = var.project_id
+  name                        = var.cluster_name
+  cluster_type                = var.cluster_type
+  provider_name               = var.provider_name
+  provider_instance_size_name = var.provider_instance_size_name
+  replication_specs {
+    num_shards = var.replication_specs.num_shards
+    dynamic "regions_config" {
+      for_each = local.regions_config_all # changed to use the local variable
+      content {
+        region_name     = regions_config.value.region_name
+        electable_nodes = regions_config.value.electable_nodes
+        priority        = regions_config.value.priority
+        read_only_nodes = regions_config.value.read_only_nodes
+      }
+    }
+  }
+}
+```
+This modified configuration file will have the same behavior as the original one, but it doesn't have individual blocks anymore, only the `dynamic` block, so it is supported by the plugin.

From 4dea79b1791cb6115535e5282f2580721f3f9c5a Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 15:31:06 +0100
Subject: [PATCH 14/15] doc adjustment

---
 docs/guide_clu2adv_dynamic_block.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/guide_clu2adv_dynamic_block.md b/docs/guide_clu2adv_dynamic_block.md
index 37933e4..69f6c96 100644
--- a/docs/guide_clu2adv_dynamic_block.md
+++ b/docs/guide_clu2adv_dynamic_block.md
@@ -95,4 +95,4 @@ resource "mongodbatlas_cluster" "this" {
   }
 }
 ```
-This modified configuration file will have the same behavior as the original one, but it doesn't have individual blocks anymore, only the `dynamic` block, so it is supported by the plugin.
+This modified configuration file has the same behavior as the original one, but it doesn't have individual blocks anymore, only the `dynamic` block, so it is supported by the plugin.

From 342043dad301db90167af045c36d9769dfb373c4 Mon Sep 17 00:00:00 2001
From: Leo Antoli <430982+lantoli@users.noreply.github.com>
Date: Thu, 20 Mar 2025 15:40:08 +0100
Subject: [PATCH 15/15] doc small change

---
 docs/guide_clu2adv_dynamic_block.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/guide_clu2adv_dynamic_block.md b/docs/guide_clu2adv_dynamic_block.md
index 69f6c96..667039c 100644
--- a/docs/guide_clu2adv_dynamic_block.md
+++ b/docs/guide_clu2adv_dynamic_block.md
@@ -6,7 +6,7 @@ If you need to use the plugin for use cases not yet supported, please send us [f
 
 ## Dynamic block and individual blocks in the same resource
 
-Dynamic block and individual blocks for `regions_config` are not supported at the same time. The recommended way to handle this is to remove the individual `regions_config` or `replication_specs` blocks and use a local variable to add the individual block information to the variable you're using in the `for_each` expression, using [concat](https://developer.hashicorp.com/terraform/language/functions/concat) if you're using a list or [setunion](https://developer.hashicorp.com/terraform/language/functions/setunion) for sets.
+Dynamic block and individual blocks for `regions_config` or `replication_specs` are not supported at the same time. The recommended way to handle this is to remove the individual `regions_config` or `replication_specs` blocks and use a local variable to add the individual block information to the variable you're using in the `for_each` expression, using [concat](https://developer.hashicorp.com/terraform/language/functions/concat) if you're using a list or [setunion](https://developer.hashicorp.com/terraform/language/functions/setunion) for sets.
 
 Let's see an example with `regions_config`, it is the same for `replication_specs`. In the original configuration file, the `mongodb_cluster` resource is used inside a module that receives the `regions_config` elements in a `list` variable and we want to add an additional `region_config` with a read-only node.
 ```hcl