feat: Supports dynamic blocks in tags and labels (#31)

* tags

* pass tests

* allow expressions

* expression_individual

* change format style

* pass tests

* full example

* refactor

* small refactors

* rename var

* readme

* typo

* doc for update plugin

* typo

* doc examples link

* change v2 to 2.0.0

* changelog

* refactor key / value attributes in dynamic blocks

Author: lantoli

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## (Unreleased)
 
+ENHANCEMENTS:
+
+* Supports `dynamic` block for `tags` and `labels`
+
 ## 1.0.0 (Mar 6, 2025)
 
 NOTES:

README.md

@@ -5,7 +5,7 @@
 This repository contains the Atlas CLI plugin for [Terraform's MongoDB Atlas Provider](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs).
 
 It has the following commands to help with your Terraform configurations:
-- **clusterToAdvancedCluster**: Convert a `mongodbatlas_cluster` Terraform configuration to `mongodbatlas_advanced_cluster` (preview provider v2).
+- **clusterToAdvancedCluster**: Convert a `mongodbatlas_cluster` Terraform configuration to `mongodbatlas_advanced_cluster` (preview provider 2.0.0).
 
 ## Installation
 
@@ -15,12 +15,22 @@ Install the plugin by running:
 ```bash
 atlas plugin install github.com/mongodb-labs/atlas-cli-plugin-terraform
 ```
+ 
+If you have it installed and want to update it to the latest version, run:
+```bash
+atlas plugin update mongodb-labs/atlas-cli-plugin-terraform
+```
+
+If you want to see the list of installed plugins or check if this plugin is installed, run:
+```bash
+atlas plugin list
+```
 
-## Convert mongodbatlas_cluster to mongodbatlas_advanced_cluster (preview provider v2)
+## Convert mongodbatlas_cluster to mongodbatlas_advanced_cluster (preview provider 2.0.0)
 
 ### Usage
 
-**Note**: In order to use the **Preview for MongoDB Atlas Provider v2** of `mongodbatlas_advanced_cluster`, you need to set the environment variable `MONGODB_ATLAS_PREVIEW_PROVIDER_V2_ADVANCED_CLUSTER` to `true`.
+**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:
 ```bash
@@ -38,12 +48,36 @@ If you want to overwrite the output file if it exists, or even use the same outp
 
 You can use the `--watch` or the `-w` flag to keep the plugin running and watching for changes in the input file. You can have input and output files open in an editor and see easily how changes to the input file affect the output file.
 
+You can find [here](https://github.com/mongodb-labs/atlas-cli-plugin-terraform/tree/main/internal/convert/testdata/clu2adv) some examples of input files (suffix .in.tf) and the corresponding output files (suffix .out.tf).
+
+### Dynamic blocks
+
+`dynamic` blocks are used to generate multiple nested blocks based on a set of values. 
+Given the different ways of using dynamic blocks, we recommend reviewing the output and making sure it fits your needs.
+
+#### Dynamic blocks in tags and labels
+
+You can use `dynamic` blocks for `tags` and `labels`. You can also combine the use of dynamic blocks in `tags` and `labels` with individual blocks in the same cluster definition, e.g.:
+```hcl
+tags {
+	key   = "environment"
+	value = var.environment
+}
+dynamic "tags" {
+	for_each = var.tags
+	content {
+		key   = tags.key
+		value = replace(tags.value, "/", "_")
+	}
+}
+```
+
 ### Limitations
 
 - The plugin doesn't support `regions_config` without `electable_nodes` as there can be some issues with `priority` when they only have `analytics_nodes` and/or `electable_nodes`.
 - [`priority`](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest/docs/resources/cluster#priority-1) is required in `regions_config` and must be a numeric [literal expression](https://developer.hashicorp.com/nomad/docs/job-specification/hcl2/expressions#literal-expressions) between 7 and 1, e.g. `var.priority` is not supported. This is to allow reordering them by descending priority as this is expected in `mongodbatlas_advanced_cluster`.
 - [`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`.
-- `dynamic` blocks to generate `replication_specs`, `regions_config`, etc. are not supported.
+- `dynamic` blocks are currently supported only for `tags` and `labels`. **Coming soon**: support for `replication_specs` and `regions_config`.
 
 ## Contributing
 

internal/cli/clu2adv/clu2adv.go

@@ -10,8 +10,8 @@ func Builder() *cobra.Command {
 	o := &opts{fs: afero.NewOsFs()}
 	cmd := &cobra.Command{
 		Use:     "clusterToAdvancedCluster",
-		Short:   "Convert cluster to advanced_cluster v2",
-		Long:    "Convert a Terraform configuration from mongodbatlas_cluster to mongodbatlas_advanced_cluster schema v2",
+		Short:   "Convert cluster to advanced_cluster preview provider 2.0.0",
+		Long:    "Convert a Terraform configuration from mongodbatlas_cluster to mongodbatlas_advanced_cluster preview provider 2.0.0",
 		Aliases: []string{"clu2adv"},
 		RunE: func(_ *cobra.Command, _ []string) error {
 			if err := o.PreRun(); err != nil {

internal/convert/const_names.go

@@ -51,4 +51,7 @@ const (
 	nMoved                      = "moved"
 	nFrom                       = "from"
 	nTo                         = "to"
+	nDynamic                    = "dynamic"
+	nForEach                    = "for_each"
+	nContent                    = "content"
 )

internal/convert/convert.go

@@ -1,8 +1,8 @@
 package convert
 
 import (
-	"errors"
 	"fmt"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -36,13 +36,17 @@ const (
 	commentRemovedOld        = "Note: Remember to remove or comment out the old cluster definitions."
 )
 
+var (
+	dynamicBlockAllowList = []string{nTags, nLabels}
+)
+
 type attrVals struct {
 	req map[string]hclwrite.Tokens
 	opt map[string]hclwrite.Tokens
 }
 
 // ClusterToAdvancedCluster transforms all mongodbatlas_cluster definitions in a
-// Terraform configuration file into mongodbatlas_advanced_cluster schema v2 definitions.
+// Terraform configuration file into mongodbatlas_advanced_cluster schema 2.0.0.
 // All other resources and data sources are left untouched.
 // Note: hclwrite.Tokens are used instead of cty.Value so expressions with interpolations like var.region can be preserved.
 // cty.Value only supports literal expressions.
@@ -224,6 +228,50 @@ func fillReplicationSpecs(resourceb *hclwrite.Body, root attrVals) error {
 }
 
 func fillTagsLabelsOpt(resourceb *hclwrite.Body, name string) error {
+	tokensDynamic, err := extractTagsLabelsDynamicBlock(resourceb, name)
+	if err != nil {
+		return err
+	}
+	tokensIndividual, err := extractTagsLabelsIndividual(resourceb, name)
+	if err != nil {
+		return err
+	}
+	if tokensDynamic != nil && tokensIndividual != nil {
+		resourceb.SetAttributeRaw(name, hcl.TokensFuncMerge(tokensDynamic, tokensIndividual))
+		return nil
+	}
+	if tokensDynamic != nil {
+		resourceb.SetAttributeRaw(name, tokensDynamic)
+	}
+	if tokensIndividual != nil {
+		resourceb.SetAttributeRaw(name, tokensIndividual)
+	}
+	return nil
+}
+
+func extractTagsLabelsDynamicBlock(resourceb *hclwrite.Body, name string) (hclwrite.Tokens, error) {
+	d, err := getDynamicBlock(resourceb, name)
+	if err != nil || d.forEach == nil {
+		return nil, err
+	}
+	key := d.content.Body().GetAttribute(nKey)
+	value := d.content.Body().GetAttribute(nValue)
+	if key == nil || value == nil {
+		return nil, fmt.Errorf("dynamic block %s: %s or %s not found", name, nKey, nValue)
+	}
+	keyExpr := replaceDynamicBlockExpr(key, name, nKey)
+	valueExpr := replaceDynamicBlockExpr(value, name, nValue)
+	collectionExpr := hcl.GetAttrExpr(d.forEach)
+	forExpr := fmt.Sprintf("for key, value in %s : %s => %s", collectionExpr, keyExpr, valueExpr)
+	tokens := hcl.TokensObjectFromExpr(forExpr)
+	if keyExpr == nKey && valueExpr == nValue { // expression can be simplified and use for_each expression
+		tokens = hcl.TokensFromExpr(collectionExpr)
+	}
+	resourceb.RemoveBlock(d.block)
+	return tokens, nil
+}
+
+func extractTagsLabelsIndividual(resourceb *hclwrite.Body, name string) (hclwrite.Tokens, error) {
 	var (
 		file  = hclwrite.NewEmptyFile()
 		fileb = file.Body()
@@ -237,16 +285,16 @@ func fillTagsLabelsOpt(resourceb *hclwrite.Body, name string) error {
 		key := block.Body().GetAttribute(nKey)
 		value := block.Body().GetAttribute(nValue)
 		if key == nil || value == nil {
-			return fmt.Errorf("%s: %s or %s not found", name, nKey, nValue)
+			return nil, fmt.Errorf("%s: %s or %s not found", name, nKey, nValue)
 		}
 		setKeyValue(fileb, key, value)
 		resourceb.RemoveBlock(block)
 		found = true
 	}
-	if found {
-		resourceb.SetAttributeRaw(name, hcl.TokensObject(fileb))
+	if !found {
+		return nil, nil
 	}
-	return nil
+	return hcl.TokensObject(fileb), nil
 }
 
 func fillBlockOpt(resourceb *hclwrite.Body, name string) {
@@ -394,13 +442,45 @@ func getResourceLabel(resource *hclwrite.Block) string {
 
 func checkDynamicBlock(body *hclwrite.Body) error {
 	for _, block := range body.Blocks() {
-		if block.Type() == "dynamic" {
-			return errors.New("dynamic blocks are not supported")
+		name := getResourceName(block)
+		if block.Type() != nDynamic || slices.Contains(dynamicBlockAllowList, name) {
+			continue
 		}
+		return fmt.Errorf("dynamic blocks are not supported for %s", name)
 	}
 	return nil
 }
 
+type dynamicBlock struct {
+	block   *hclwrite.Block
+	forEach *hclwrite.Attribute
+	content *hclwrite.Block
+}
+
+func getDynamicBlock(body *hclwrite.Body, name string) (dynamicBlock, error) {
+	for _, block := range body.Blocks() {
+		if block.Type() != nDynamic || name != getResourceName(block) {
+			continue
+		}
+		blockb := block.Body()
+		forEach := blockb.GetAttribute(nForEach)
+		if forEach == nil {
+			return dynamicBlock{}, fmt.Errorf("dynamic block %s: attribute %s not found", name, nForEach)
+		}
+		content := blockb.FirstMatchingBlock(nContent, nil)
+		if content == nil {
+			return dynamicBlock{}, fmt.Errorf("dynamic block %s: block %s not found", name, nContent)
+		}
+		return dynamicBlock{forEach: forEach, block: block, content: content}, nil
+	}
+	return dynamicBlock{}, nil
+}
+
+func replaceDynamicBlockExpr(attr *hclwrite.Attribute, blockName, attrName string) string {
+	expr := hcl.GetAttrExpr(attr)
+	return strings.ReplaceAll(expr, fmt.Sprintf("%s.%s", blockName, attrName), attrName)
+}
+
 func setKeyValue(body *hclwrite.Body, key, value *hclwrite.Attribute) {
 	keyStr, err := hcl.GetAttrString(key, "")
 	if err == nil {