feat: Converts clusters with one replication_specs, regions_config and shard

internal/hcl/hcl.go

@@ -10,25 +10,6 @@ import (
 	"github.com/zclconf/go-cty/cty"
 )
 
-const (
-	resourceType                 = "resource"
-	cluster                      = "mongodbatlas_cluster"
-	advCluster                   = "mongodbatlas_advanced_cluster"
-	nameReplicationSpecs         = "replication_specs"
-	nameRegionConfigs            = "region_configs"
-	nameElectableSpecs           = "electable_specs"
-	nameProviderRegionName       = "provider_region_name"
-	nameRegionName               = "region_name"
-	nameProviderName             = "provider_name"
-	nameBackingProviderName      = "backing_provider_name"
-	nameProviderInstanceSizeName = "provider_instance_size_name"
-	nameInstanceSize             = "instance_size"
-	nameClusterType              = "cluster_type"
-	namePriority                 = "priority"
-
-	errFreeCluster = "free cluster (because no " + nameReplicationSpecs + ")"
-)
-
 // ClusterToAdvancedCluster transforms all mongodbatlas_cluster definitions in a
 // Terraform configuration file into mongodbatlas_advanced_cluster schema v2 definitions.
 // All other resources and data sources are left untouched.
@@ -45,67 +26,195 @@ func ClusterToAdvancedCluster(config []byte) ([]byte, error) {
 		if resource.Type() != resourceType || resourceName != cluster {
 			continue
 		}
-		resourceBody := resource.Body()
+		resourceb := resource.Body()
 		labels[0] = advCluster
 		resource.SetLabels(labels)
 
-		if isFreeTier(resourceBody) {
-			if err := fillFreeTier(resourceBody); err != nil {
-				return nil, err
-			}
+		if resourceb.FirstMatchingBlock(nRepSpecs, nil) != nil {
+			err = fillReplicationSpecs(resourceb)
+		} else {
+			err = fillFreeTier(resourceb)
+		}
+		if err != nil {
+			return nil, err
 		}
 
-		resourceBody.AppendNewline()
-		appendComment(resourceBody, "Generated by atlas-cli-plugin-terraform.")
-		appendComment(resourceBody, "Please confirm that all references to this resource are updated.")
+		resourceb.AppendNewline()
+		appendComment(resourceb, "Generated by atlas-cli-plugin-terraform.")
+		appendComment(resourceb, "Please confirm that all references to this resource are updated.")
 	}
 	return parser.Bytes(), nil
 }
 
-func isFreeTier(body *hclwrite.Body) bool {
-	return body.FirstMatchingBlock(nameReplicationSpecs, nil) == nil
-}
-
-func fillFreeTier(body *hclwrite.Body) error {
-	const (
-		valClusterType = "REPLICASET"
-		valPriority    = 7
-	)
-	body.SetAttributeValue(nameClusterType, cty.StringVal(valClusterType))
-	regionConfig := hclwrite.NewEmptyFile()
-	regionConfigBody := regionConfig.Body()
-	setAttrInt(regionConfigBody, "priority", valPriority)
-	if err := moveAttribute(nameProviderRegionName, nameRegionName, body, regionConfigBody, errFreeCluster); err != nil {
+// fillFreeTier is the entry point to convert clusters in free tier
+func fillFreeTier(resourceb *hclwrite.Body) error {
+	resourceb.SetAttributeValue(nClusterType, cty.StringVal(valClusterType))
+	config := hclwrite.NewEmptyFile()
+	configb := config.Body()
+	setAttrInt(configb, "priority", valPriority)
+	if err := moveAttr(resourceb, configb, nRegionNameSrc, nRegionName, errFreeCluster); err != nil {
 		return err
 	}
-	if err := moveAttribute(nameProviderName, nameProviderName, body, regionConfigBody, errFreeCluster); err != nil {
+	if err := moveAttr(resourceb, configb, nProviderName, nProviderName, errFreeCluster); err != nil {
 		return err
 	}
-	if err := moveAttribute(nameBackingProviderName, nameBackingProviderName, body, regionConfigBody, errFreeCluster); err != nil {
+	if err := moveAttr(resourceb, configb, nBackingProviderName, nBackingProviderName, errFreeCluster); err != nil {
 		return err
 	}
 	electableSpec := hclwrite.NewEmptyFile()
-	if err := moveAttribute(nameProviderInstanceSizeName, nameInstanceSize, body, electableSpec.Body(), errFreeCluster); err != nil {
+	if err := moveAttr(resourceb, electableSpec.Body(), nInstanceSizeSrc, nInstanceSize, errFreeCluster); err != nil {
 		return err
 	}
-	regionConfigBody.SetAttributeRaw(nameElectableSpecs, tokensObject(electableSpec))
+	configb.SetAttributeRaw(nElectableSpecs, tokensObject(electableSpec))
 
-	replicationSpec := hclwrite.NewEmptyFile()
-	replicationSpec.Body().SetAttributeRaw(nameRegionConfigs, tokensArrayObject(regionConfig))
-	body.SetAttributeRaw(nameReplicationSpecs, tokensArrayObject(replicationSpec))
+	repSpecs := hclwrite.NewEmptyFile()
+	repSpecs.Body().SetAttributeRaw(nConfig, tokensArrayObject(config))
+	resourceb.SetAttributeRaw(nRepSpecs, tokensArrayObject(repSpecs))
 	return nil
 }
 
-func moveAttribute(fromAttrName, toAttrName string, fromBody, toBody *hclwrite.Body, errPrefix string) error {
-	attr := fromBody.GetAttribute(fromAttrName)
-	if attr == nil {
-		return fmt.Errorf("%s: attribute %s not found", errPrefix, fromAttrName)
+// fillReplicationSpecs is the entry point to convert clusters with replications_specs (all but free tier)
+func fillReplicationSpecs(resourceb *hclwrite.Body) error {
+	root, errRoot := popRootAttrs(resourceb, errRepSpecs)
+	if errRoot != nil {
+		return errRoot
 	}
-	fromBody.RemoveAttribute(fromAttrName)
-	toBody.SetAttributeRaw(toAttrName, attr.Expr().BuildTokens(nil))
+	repSpecsSrc := resourceb.FirstMatchingBlock(nRepSpecs, nil)
+	configSrc := repSpecsSrc.Body().FirstMatchingBlock(nConfigSrc, nil)
+	if configSrc == nil {
+		return fmt.Errorf("%s: %s not found", errRepSpecs, nConfigSrc)
+	}
+
+	resourceb.RemoveAttribute(nNumShards) // num_shards in root is not relevant, only in replication_specs
+	// ok to fail as cloud_backup is optional
+	_ = moveAttr(resourceb, resourceb, nCloudBackup, nBackupEnabled, errRepSpecs)
+
+	config, errConfig := getRegionConfigs(configSrc, root)
+	if errConfig != nil {
+		return errConfig
+	}
+	repSpecs := hclwrite.NewEmptyFile()
+	repSpecs.Body().SetAttributeRaw(nConfig, config)
+	resourceb.SetAttributeRaw(nRepSpecs, tokensArrayObject(repSpecs))
+
+	resourceb.RemoveBlock(repSpecsSrc)
 	return nil
 }
 
+// popRootAttrs deletes the attributes common to all replication_specs/regions_config and returns them.
+func popRootAttrs(body *hclwrite.Body, errPrefix string) (attrVals, error) {
+	var (
+		reqNames = []string{
+			nProviderName,
+			nInstanceSizeSrc,
+		}
+		optNames = []string{
+			nDiskSizeGB,
+			nDiskGBEnabledSrc,
+			nComputeEnabledSrc,
+			nComputeMinInstanceSizeSrc,
+			nComputeMaxInstanceSizeSrc,
+			nComputeScaleDownEnabledSrc,
+		}
+		req = make(map[string]hclwrite.Tokens)
+		opt = make(map[string]hclwrite.Tokens)
+	)
+	for _, name := range reqNames {
+		tokens, err := popAttr(body, name, errPrefix)
+		if err != nil {
+			return attrVals{}, err
+		}
+		req[name] = tokens
+	}
+	for _, name := range optNames {
+		tokens, _ := popAttr(body, name, errPrefix)
+		if tokens != nil {
+			opt[name] = tokens
+		}
+	}
+	return attrVals{req: req, opt: opt}, nil
+}
+
+func getRegionConfigs(configSrc *hclwrite.Block, root attrVals) (hclwrite.Tokens, error) {
+	file := hclwrite.NewEmptyFile()
+	fileb := file.Body()
+	fileb.SetAttributeRaw(nProviderName, root.req[nProviderName])
+	if err := moveAttr(configSrc.Body(), fileb, nRegionName, nRegionName, errRepSpecs); err != nil {
+		return nil, err
+	}
+	if err := moveAttr(configSrc.Body(), fileb, nPriority, nPriority, errRepSpecs); err != nil {
+		return nil, err
+	}
+	autoScaling := getAutoScalingOpt(root.opt)
+	if autoScaling != nil {
+		fileb.SetAttributeRaw(nAutoScaling, autoScaling)
+	}
+	electableSpecs, errElect := getElectableSpecs(configSrc, root)
+	if errElect != nil {
+		return nil, errElect
+	}
+	fileb.SetAttributeRaw(nElectableSpecs, electableSpecs)
+	return tokensArrayObject(file), nil
+}
+
+func getElectableSpecs(configSrc *hclwrite.Block, root attrVals) (hclwrite.Tokens, error) {
+	file := hclwrite.NewEmptyFile()
+	fileb := file.Body()
+	if err := moveAttr(configSrc.Body(), fileb, nElectableNodes, nNodeCount, errRepSpecs); err != nil {
+		return nil, err
+	}
+	fileb.SetAttributeRaw(nInstanceSize, root.req[nInstanceSizeSrc])
+	if root.opt[nDiskSizeGB] != nil {
+		fileb.SetAttributeRaw(nDiskSizeGB, root.opt[nDiskSizeGB])
+	}
+	return tokensObject(file), nil
+}
+
+func getAutoScalingOpt(opt map[string]hclwrite.Tokens) hclwrite.Tokens {
+	var (
+		names = [][2]string{ // use slice instead of map to preserve order
+			{nDiskGBEnabledSrc, nDiskGBEnabled},
+			{nComputeEnabledSrc, nComputeEnabled},
+			{nComputeMinInstanceSizeSrc, nComputeMinInstanceSize},
+			{nComputeMaxInstanceSizeSrc, nComputeMaxInstanceSize},
+			{nComputeScaleDownEnabledSrc, nComputeScaleDownEnabled},
+		}
+		file  = hclwrite.NewEmptyFile()
+		found = false
+	)
+	for _, tuple := range names {
+		src, dst := tuple[0], tuple[1]
+		if tokens := opt[src]; tokens != nil {
+			file.Body().SetAttributeRaw(dst, tokens)
+			found = true
+		}
+	}
+	if !found {
+		return nil
+	}
+	return tokensObject(file)
+}
+
+// popAttr deletes an attribute from fromBody and adds it to toBody.
+func moveAttr(fromBody, toBody *hclwrite.Body, fromAttrName, toAttrName, errPrefix string) error {
+	tokens, err := popAttr(fromBody, fromAttrName, errPrefix)
+	if err == nil {
+		toBody.SetAttributeRaw(toAttrName, tokens)
+	}
+	return err
+}
+
+// popAttr deletes an attribute and returns it value.
+func popAttr(body *hclwrite.Body, attrName, errPrefix string) (hclwrite.Tokens, error) {
+	attr := body.GetAttribute(attrName)
+	if attr == nil {
+		return nil, fmt.Errorf("%s: attribute %s not found", errPrefix, attrName)
+	}
+	tokens := attr.Expr().BuildTokens(nil)
+	body.RemoveAttribute(attrName)
+	return tokens, nil
+}
+
 func setAttrInt(body *hclwrite.Body, attrName string, number int) {
 	tokens := hclwrite.Tokens{
 		{Type: hclsyntax.TokenNumberLit, Bytes: []byte(strconv.Itoa(number))},
@@ -148,3 +257,50 @@ func getParser(config []byte) (*hclwrite.File, error) {
 	}
 	return parser, nil
 }
+
+type attrVals struct {
+	req map[string]hclwrite.Tokens
+	opt map[string]hclwrite.Tokens
+}
+
+const (
+	resourceType = "resource"
+	cluster      = "mongodbatlas_cluster"
+	advCluster   = "mongodbatlas_advanced_cluster"
+
+	nRepSpecs                   = "replication_specs"
+	nConfig                     = "region_configs"
+	nConfigSrc                  = "regions_config"
+	nElectableSpecs             = "electable_specs"
+	nAutoScaling                = "auto_scaling"
+	nRegionNameSrc              = "provider_region_name"
+	nRegionName                 = "region_name"
+	nProviderName               = "provider_name"
+	nBackingProviderName        = "backing_provider_name"
+	nInstanceSizeSrc            = "provider_instance_size_name"
+	nInstanceSize               = "instance_size"
+	nClusterType                = "cluster_type"
+	nPriority                   = "priority"
+	nNumShards                  = "num_shards"
+	nBackupEnabled              = "backup_enabled"
+	nCloudBackup                = "cloud_backup"
+	nDiskSizeGB                 = "disk_size_gb"
+	nDiskGBEnabledSrc           = "auto_scaling_disk_gb_enabled"
+	nComputeEnabledSrc          = "auto_scaling_compute_enabled"
+	nComputeScaleDownEnabledSrc = "auto_scaling_compute_scale_down_enabled"
+	nComputeMinInstanceSizeSrc  = "provider_auto_scaling_compute_min_instance_size"
+	nComputeMaxInstanceSizeSrc  = "provider_auto_scaling_compute_max_instance_size"
+	nDiskGBEnabled              = "disk_gb_enabled"
+	nComputeEnabled             = "compute_enabled"
+	nComputeScaleDownEnabled    = "compute_scale_down_enabled"
+	nComputeMinInstanceSize     = "compute_min_instance_size"
+	nComputeMaxInstanceSize     = "compute_max_instance_size"
+	nNodeCount                  = "node_count"
+	nElectableNodes             = "electable_nodes"
+
+	valClusterType = "REPLICASET"
+	valPriority    = 7
+
+	errFreeCluster = "free cluster (because no " + nRepSpecs + ")"
+	errRepSpecs    = "setting " + nRepSpecs
+)

internal/hcl/hcl_test.go

@@ -35,15 +35,17 @@ func TestClusterToAdvancedCluster(t *testing.T) {
 	assert.NotEmpty(t, inputFiles)
 	for _, inputFile := range inputFiles {
 		testName := strings.TrimSuffix(filepath.Base(inputFile), inSuffix)
-		inConfig, err := afero.ReadFile(fs, inputFile)
-		require.NoError(t, err)
-		outConfig, err := hcl.ClusterToAdvancedCluster(inConfig)
-		if err == nil {
-			g.Assert(t, testName, outConfig)
-		} else {
-			errMsg, found := errMap[testName]
-			assert.True(t, found, "error not found for test %s", testName)
-			assert.Contains(t, err.Error(), errMsg)
-		}
+		t.Run(testName, func(t *testing.T) {
+			inConfig, err := afero.ReadFile(fs, inputFile)
+			require.NoError(t, err)
+			outConfig, err := hcl.ClusterToAdvancedCluster(inConfig)
+			if err == nil {
+				g.Assert(t, testName, outConfig)
+			} else {
+				errMsg, found := errMap[testName]
+				assert.True(t, found, "error not found for test %s", testName)
+				assert.Contains(t, err.Error(), errMsg)
+			}
+		})
 	}
 }

internal/hcl/testdata/clu2adv/autoscaling.in.tf

@@ -0,0 +1,33 @@
+resource "mongodbatlas_cluster" "autoscaling" {
+  project_id   = var.project_id
+  name         = var.cluster_name
+  disk_size_gb = 100
+  num_shards = 1
+  cluster_type = "REPLICASET"
+
+  replication_specs {
+    num_shards = 1
+    regions_config {
+      region_name     = "US_WEST_2"
+      electable_nodes = 3
+      priority        = 7
+      read_only_nodes = 0
+    }
+  }
+  cloud_backup                            = true
+  auto_scaling_disk_gb_enabled            = true
+  auto_scaling_compute_enabled            = false
+  auto_scaling_compute_scale_down_enabled = local.scale_down
+
+  //Provider Settings "block"
+  provider_name                                   = "AWS"
+  provider_auto_scaling_compute_min_instance_size = "M10"
+  provider_auto_scaling_compute_max_instance_size = "M40"
+  provider_instance_size_name                     = "M20"
+
+  lifecycle { // To simulate if there a new instance size name to avoid scale cluster down to original value
+    # Note that provider_instance_size_name won't exist in advanced_cluster so it's an error to refer to it,
+    # but plugin doesn't help here.
+    ignore_changes = [provider_instance_size_name]
+  }
+}