replace-triggered-by must reference a valid resource or resource attribute

Author: dsa0x

internal/terraform/context_plan2_test.go

@@ -4399,6 +4399,52 @@ resource "test_object" "b" {
 }
 }
 
+func TestContext2Plan_triggeredByInvalid(t *testing.T) {
+m := testModuleInline(t, map[string]string{
+"main.tf": `
+resource "test_object" "a" {
+count = 1
+test_string = "new"
+}
+resource "test_object" "b" {
+count = 1
+test_string = test_object.a[count.index].test_string
+lifecycle {
+# reference to an invalid attribute "yikes" should cause an error
+replace_triggered_by = [ test_object.a[count.index].yikes ]
+}
+}
+`,
+})
+
+p := simpleMockProvider()
+
+ctx := testContext2(t, &ContextOpts{
+Providers: map[addrs.Provider]providers.Factory{
+addrs.NewDefaultProvider("test"): testProviderFuncFixed(p),
+},
+})
+
+state := states.BuildState(func(s *states.SyncState) {
+s.SetResourceInstanceCurrent(
+mustResourceInstanceAddr("test_object.a[0]"),
+&states.ResourceInstanceObjectSrc{
+AttrsJSON: []byte(`{"test_string":"old"}`),
+Status: states.ObjectReady,
+},
+mustProviderConfig(`provider["registry.terraform.io/hashicorp/test"]`),
+)
+})
+
+_, diags := ctx.Plan(m, state, &PlanOpts{
+Mode: plans.NormalMode,
+})
+fmt.Println(diags.Err().Error())
+if !diags.HasErrors() {
+t.Fatalf("expected errors, got none")
+}
+}
+
 func TestContext2Plan_dataSchemaChange(t *testing.T) {
 // We can't decode the prior state when a data source upgrades the schema
 // in an incompatible way. Since prior state for data sources is purely

internal/terraform/eval_context_builtin.go

@@ -407,10 +407,7 @@ func (ctx *BuiltinEvalContext) EvaluateReplaceTriggeredBy(expr hcl.Expression, r
 return nil, false, diags
 }
 
-path, _ := traversalToPath(ref.Remaining)
-attrBefore, _ := path.Apply(change.Before)
-attrAfter, _ := path.Apply(change.After)
-
+attrBefore, attrAfter, diags := evalTriggeredByRefPath(ref, change)
 if attrBefore == cty.NilVal || attrAfter == cty.NilVal {
 replace := attrBefore != attrAfter
 return ref, replace, diags
@@ -421,6 +418,42 @@ func (ctx *BuiltinEvalContext) EvaluateReplaceTriggeredBy(expr hcl.Expression, r
 return ref, replace, diags
 }
 
+// evalTriggeredByRefPath evaluates the attribute reference path in the context of the
+// resource change objects. It returns the before and after values of the attribute
+// and any diagnostics that occurred during evaluation.
+func evalTriggeredByRefPath(ref *addrs.Reference, change *plans.ResourceInstanceChange) (cty.Value, cty.Value, tfdiags.Diagnostics) {
+var diags tfdiags.Diagnostics
+path, key := traversalToPath(ref.Remaining)
+
+applyPath := func(value cty.Value) (cty.Value, tfdiags.Diagnostics) {
+attr, err := path.Apply(value)
+if err != nil {
+return cty.NilVal, tfdiags.Diagnostics{}.Append(tfdiags.AttributeValue(
+tfdiags.Error,
+"Invalid attribute path",
+fmt.Sprintf(
+"The specified path %q could not be applied to the object specified in replace_triggered_by:\n"+
+"Path: %s\n"+
+"Error: %s\n"+
+"Please check your configuration and ensure the path is valid.",
+key, ref.DisplayString(), err.Error(),
+),
+path,
+))
+}
+return attr, nil
+}
+
+// Apply the path to the "before" and "after" states
+attrBefore, beforeDiags := applyPath(change.Before)
+diags = diags.AppendWithoutDuplicates(beforeDiags...)
+
+attrAfter, afterDiags := applyPath(change.After)
+diags = diags.AppendWithoutDuplicates(afterDiags...)
+
+return attrBefore, attrAfter, diags
+}
+
 func (ctx *BuiltinEvalContext) EvaluationScope(self addrs.Referenceable, source addrs.Referenceable, keyData InstanceKeyEvalData) *lang.Scope {
 switch scope := ctx.scope.(type) {
 case evalContextModuleInstance: