Merge pull request #398 from magodo/import_block

Resource mapping file will now be generated together with the `import.tf` that is the TF plannable import blocks

internal/meta/base_meta.go

@@ -10,6 +10,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/hashicorp/go-version"
 	tfjson "github.com/hashicorp/terraform-json"
 
 	"github.com/Azure/aztfexport/pkg/config"
@@ -178,6 +179,9 @@ func NewBaseMeta(cfg config.CommonConfig) (*baseMeta, error) {
 	if outputFileNames.MainFileName == "" {
 		outputFileNames.MainFileName = "main.tf"
 	}
+	if outputFileNames.ImportBlockFileName == "" {
+		outputFileNames.ImportBlockFileName = "import.tf"
+	}
 
 	tc := cfg.TelemetryClient
 	if tc == nil {
@@ -359,26 +363,56 @@ func (meta baseMeta) GenerateCfg(ctx context.Context, l ImportList) error {
 	return meta.generateCfg(ctx, l, meta.lifecycleAddon, meta.addDependency)
 }
 
-func (meta baseMeta) ExportResourceMapping(_ context.Context, l ImportList) error {
+func (meta baseMeta) ExportResourceMapping(ctx context.Context, l ImportList) error {
 	m := resmap.ResourceMapping{}
 	for _, item := range l {
 		if item.Skip() {
 			continue
 		}
+
+		// The JSON mapping record
 		m[item.AzureResourceID.String()] = resmap.ResourceMapEntity{
 			ResourceId:   item.TFResourceId,
 			ResourceType: item.TFAddr.Type,
 			ResourceName: item.TFAddr.Name,
 		}
 	}
-	output := filepath.Join(meta.outdir, ResourceMappingFileName)
 	b, err := json.MarshalIndent(m, "", "\t")
 	if err != nil {
 		return fmt.Errorf("JSON marshalling the resource mapping: %v", err)
 	}
+	oMapFile := filepath.Join(meta.outdir, ResourceMappingFileName)
 	// #nosec G306
-	if err := os.WriteFile(output, b, 0644); err != nil {
-		return fmt.Errorf("writing the resource mapping to %s: %v", output, err)
+	if err := os.WriteFile(oMapFile, b, 0644); err != nil {
+		return fmt.Errorf("writing the resource mapping to %s: %v", oMapFile, err)
+	}
+
+	// Only generate import.tf when the current using terraform supports plannable import
+	var supportPlannableImport bool
+	if meta.tf == nil {
+		supportPlannableImport = true
+	} else {
+		ver, _, err := meta.tf.Version(ctx, true)
+		if err != nil {
+			return fmt.Errorf("getting terraform version")
+		}
+		supportPlannableImport = ver.GreaterThanOrEqual(version.Must(version.NewVersion("v1.5.0")))
+	}
+	if supportPlannableImport {
+		f := hclwrite.NewFile()
+		body := f.Body()
+		for _, item := range l {
+			// The import block
+			blk := hclwrite.NewBlock("import", nil)
+			blk.Body().SetAttributeValue("id", cty.StringVal(item.TFResourceId))
+			blk.Body().SetAttributeTraversal("to", hcl.Traversal{hcl.TraverseRoot{Name: item.TFAddr.Type}, hcl.TraverseAttr{Name: item.TFAddr.Name}})
+			body.AppendBlock(blk)
+		}
+		oImportFile := filepath.Join(meta.moduleDir, meta.outputFileNames.ImportBlockFileName)
+		// #nosec G306
+		if err := os.WriteFile(oImportFile, f.Bytes(), 0644); err != nil {
+			return fmt.Errorf("writing the import block to %s: %v", oImportFile, err)
+		}
 	}
 	return nil
 }

main.go

@@ -324,9 +324,10 @@ func main() {
 	mappingFileFlags := append([]cli.Flag{}, commonFlags...)
 
 	safeOutputFileNames := config.OutputFileNames{
-		TerraformFileName: "terraform.aztfexport.tf",
-		ProviderFileName:  "provider.aztfexport.tf",
-		MainFileName:      "main.aztfexport.tf",
+		TerraformFileName:   "terraform.aztfexport.tf",
+		ProviderFileName:    "provider.aztfexport.tf",
+		MainFileName:        "main.aztfexport.tf",
+		ImportBlockFileName: "import.aztfexport.tf",
 	}
 
 	app := &cli.App{

pkg/config/config.go

@@ -15,6 +15,8 @@ type OutputFileNames struct {
 	ProviderFileName string
 	// The filename for the generated "main.tf" (default)
 	MainFileName string
+	// The filename for the generated "import.tf" (default)
+	ImportBlockFileName string
 }
 
 type CommonConfig struct {