Add handling of empty feature blocks (#3580)

* Add handling of empty feature blocks * partial config cleanup * Documentation update
gruntwork-io · Nov 19, 2024 · 533bc11 · 533bc11
1 parent e8f09ca
commit 533bc11
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Showing 5 changed files with 41 additions and 5 deletions.
diff --git a/config/config_partial.go b/config/config_partial.go
@@ -147,6 +147,19 @@ func DecodeBaseBlocks(ctx *ParsingContext, file *hclparse.File, includeFromChild
 	if err := file.Decode(&tgFlags, evalParsingContext); err != nil {
 		return nil, err
 	}
+	// validate flags to have default value, collect errors
+	flagErrs := &errors.MultiError{}
+
+	for _, flag := range tgFlags.FeatureFlags {
+		if flag.Default == nil {
+			flagErr := fmt.Errorf("feature flag %s does not have a default value in %s", flag.Name, file.ConfigPath)
+			flagErrs = flagErrs.Append(flagErr)
+		}
+	}
+
+	if flagErrs.ErrorOrNil() != nil {
+		return nil, flagErrs
+	}
 
 	flagsAsCtyVal, err := flagsAsCty(ctx, tgFlags.FeatureFlags)
 	if err != nil {

diff --git a/docs/_docs/04_reference/config-blocks-and-attributes.md b/docs/_docs/04_reference/config-blocks-and-attributes.md
@@ -1173,8 +1173,9 @@ More details in [engine section](https://terragrunt.gruntwork.io/docs/features/e
 
 ### feature
 
-The `feature` block is used to configure feature flags in HCL for a particular Terragrunt Unit.
-Feature flags can have default values, and they can be set through a CLI flag (`--feature`) or an environment variable (`TERRAGRUNT_FEATURE`).
+The `feature` block is used to configure feature flags in HCL for a specific Terragrunt Unit.
+Each feature flag must include a default value; failing to specify a default value will result in an error.
+Feature flags can be overridden via a CLI flag (`--feature`) or an environment variable (`TERRAGRUNT_FEATURE`).
 
 ```hcl
 feature "string_flag" {

diff --git a/test/fixtures/feature-flags/error-empty-flag/main.tf b/test/fixtures/feature-flags/error-empty-flag/main.tf
diff --git a/test/fixtures/feature-flags/error-empty-flag/terragrunt.hcl b/test/fixtures/feature-flags/error-empty-flag/terragrunt.hcl
@@ -0,0 +1,5 @@
+feature "test1" {}
+
+feature "test2" {}
+
+feature "test3" {}
diff --git a/test/integration_feature_flags_test.go b/test/integration_feature_flags_test.go
@@ -13,9 +13,10 @@ import (
 )
 
 const (
-	testSimpleFlag  = "fixtures/feature-flags/simple-flag"
-	testIncludeFlag = "fixtures/feature-flags/include-flag"
-	testRunAllFlag  = "fixtures/feature-flags/run-all"
+	testSimpleFlag     = "fixtures/feature-flags/simple-flag"
+	testIncludeFlag    = "fixtures/feature-flags/include-flag"
+	testRunAllFlag     = "fixtures/feature-flags/run-all"
+	testErrorEmptyFlag = "fixtures/feature-flags/error-empty-flag"
 )
 
 func TestFeatureFlagDefaults(t *testing.T) {
@@ -105,6 +106,22 @@ func TestFeatureFlagRunAll(t *testing.T) {
 	validateOutputs(t, app2)
 }
 
+func TestFailOnEmptyFeatureFlag(t *testing.T) {
+	t.Parallel()
+
+	cleanupTerraformFolder(t, testErrorEmptyFlag)
+	tmpEnvPath := helpers.CopyEnvironment(t, testErrorEmptyFlag)
+	rootPath := util.JoinPath(tmpEnvPath, testErrorEmptyFlag)
+
+	_, _, err := helpers.RunTerragruntCommandWithOutput(t, "terragrunt apply -auto-approve --terragrunt-non-interactive --terragrunt-working-dir "+rootPath)
+	require.Error(t, err)
+
+	message := err.Error()
+	assert.Contains(t, message, "feature flag test1 does not have a default value")
+	assert.Contains(t, message, "feature flag test2 does not have a default value")
+	assert.Contains(t, message, "feature flag test3 does not have a default value")
+}
+
 func expectedDefaults() map[string]interface{} {
 	return map[string]interface{}{
 		"string_feature_flag": "test",