Fix the inconsistent behaviour of get_terragrunt_dir function (#4443)

Co-authored-by: James Kwon <[email protected]>

Author: james03160927

config/config_helpers.go

@@ -271,7 +271,12 @@ func getPathToRepoRoot(ctx *ParsingContext, l log.Logger) (string, error) {
 
 // GetTerragruntDir returns the directory where the Terragrunt configuration file lives.
 func GetTerragruntDir(ctx *ParsingContext, l log.Logger) (string, error) {
-	terragruntConfigFileAbsPath, err := filepath.Abs(ctx.TerragruntOptions.TerragruntConfigPath)
+	path := ctx.TerragruntOptions.TerragruntConfigPath
+	if val, ok := ctx.Context.Value(stackParserContext{}).(stackParserContext); ok {
+		path = val.stackConfigFile
+	}
+
+	terragruntConfigFileAbsPath, err := filepath.Abs(path)
 	if err != nil {
 		return "", errors.New(err)
 	}

config/stack.go

@@ -72,6 +72,10 @@ type Stack struct {
 	Path         string     `hcl:"path,attr"`
 }
 
+type stackParserContext struct {
+	stackConfigFile string
+}
+
 // GenerateStacks generates the stack files.
 func GenerateStacks(ctx context.Context, l log.Logger, opts *options.TerragruntOptions) error {
 	processedFiles := make(map[string]bool)
@@ -687,6 +691,7 @@ func (u *Unit) ReadOutputs(ctx context.Context, l log.Logger, opts *options.Terr
 func ReadStackConfigFile(ctx context.Context, l log.Logger, opts *options.TerragruntOptions, filePath string, values *cty.Value) (*StackConfig, error) {
 	l.Debugf("Reading Terragrunt stack config file at %s", filePath)
 
+	ctx = context.WithValue(ctx, stackParserContext{}, stackParserContext{stackConfigFile: filePath})
 	parser := NewParsingContext(ctx, l, opts)
 
 	file, err := hclparse.NewParser(parser.ParserOptions...).ParseFromFile(filePath)

test/fixtures/stacks/terragrunt-dir/live/root.hcl

@@ -0,0 +1,7 @@
+unit "unit_a" {
+  source = "../../unit_a"
+  path   = "unit_a"
+  values = {
+    terragrunt_dir = get_terragrunt_dir()
+  }
+}

test/fixtures/stacks/terragrunt-dir/live/tennant_1/terragrunt.stack.hcl

@@ -0,0 +1,5 @@
+variable "terragrunt_dir" {}
+
+output "terragrunt_dir" {
+  value = var.terragrunt_dir
+}

test/fixtures/stacks/terragrunt-dir/unit_a/main.tf

@@ -0,0 +1,12 @@
+
+include "root" {
+  path = find_in_parent_folders("root.hcl")
+}
+
+terraform {
+  source = "."
+}
+
+inputs = {
+  terragrunt_dir = values.terragrunt_dir
+}

test/fixtures/stacks/terragrunt-dir/unit_a/terragrunt.hcl

@@ -47,6 +47,7 @@ const (
 	testFixtureStackSelfInclude                = "fixtures/stacks/self-include"
 	testFixtureStackNestedOutputs              = "fixtures/stacks/nested-outputs"
 	testFixtureStackNoValidation               = "fixtures/stacks/no-validation"
+	testFixtureStackTerragruntDir              = "fixtures/stacks/terragrunt-dir"
 )
 
 func TestStacksGenerateBasic(t *testing.T) {
@@ -1296,3 +1297,20 @@ func validateStackDir(t *testing.T, path string) {
 
 	assert.True(t, hasSubdirectories, "The .terragrunt-stack directory should contain at least one subdirectory")
 }
+
+func TestStackTerragruntDir(t *testing.T) {
+	t.Parallel()
+
+	helpers.CleanupTerraformFolder(t, testFixtureStackTerragruntDir)
+	tmpEnvPath := helpers.CopyEnvironment(t, testFixtureStackTerragruntDir)
+	gitPath := util.JoinPath(tmpEnvPath, testFixtureStackTerragruntDir)
+	helpers.CreateGitRepo(t, gitPath)
+	rootPath := util.JoinPath(gitPath, "live")
+
+	_, _, err := helpers.RunTerragruntCommandWithOutput(t, "terragrunt stack generate --no-stack-validate --working-dir "+rootPath)
+	require.NoError(t, err)
+
+	out, _, err := helpers.RunTerragruntCommandWithOutput(t, "terragrunt apply --all --non-interactive --working-dir "+rootPath)
+	require.NoError(t, err)
+	assert.Contains(t, out, `terragrunt_dir = "./tennant_1"`)
+}