terraform: Error message for unknown error_message in variable validation

internal/terraform/eval_variable.go

@@ -427,8 +427,23 @@ func evalVariableValidation(validation *configs.CheckRule, hclCtx *hcl.EvalConte
  return checkResult{Status: status}, diags
  }
 
+ if !errorValue.IsKnown() {
+ diags = diags.Append(&hcl.Diagnostic{
+ Severity: hcl.DiagError,
+ Summary: "Invalid error message",
+ Detail: "Unsuitable value for error message: expression refers to values that won't be known until the apply phase.",
+ Subject: validation.ErrorMessage.Range().Ptr(),
+ Expression: validation.ErrorMessage,
+ EvalContext: hclCtx,
+ Extra: diagnosticCausedByUnknown(true),
+ })
+ return checkResult{
+ Status: checks.StatusError,
+ }, diags
+ }
+
  var errorMessage string
- if !errorDiags.HasErrors() && errorValue.IsKnown() && !errorValue.IsNull() {
+ if !errorDiags.HasErrors() && !errorValue.IsNull() {
  var err error
  errorValue, err = convert.Convert(errorValue, cty.String)
  if err != nil {

internal/terraform/eval_variable_test.go

@@ -9,10 +9,12 @@ import (
  "testing"
 
  "github.com/hashicorp/hcl/v2"
+ "github.com/hashicorp/hcl/v2/hcltest"
  "github.com/zclconf/go-cty/cty"
 
  "github.com/hashicorp/terraform/internal/addrs"
  "github.com/hashicorp/terraform/internal/checks"
+ "github.com/hashicorp/terraform/internal/configs"
  "github.com/hashicorp/terraform/internal/lang"
  "github.com/hashicorp/terraform/internal/lang/marks"
  "github.com/hashicorp/terraform/internal/namedvals"
@@ -1374,3 +1376,47 @@ variable "bar" {
  })
  }
 }
+
+func TestEvalVariableValidation_unknownValues(t *testing.T) {
+ t.Run("known condition, unknown error_message", func(t *testing.T) {
+ rule := &configs.CheckRule{
+ Condition: hcltest.MockExprLiteral(cty.False),
+ ErrorMessage: hcltest.MockExprLiteral(cty.UnknownVal(cty.String)),
+ }
+ hclCtx := &hcl.EvalContext{}
+ varAddr := addrs.AbsInputVariableInstance{
+ Module: addrs.RootModuleInstance,
+ Variable: addrs.InputVariable{Name: "foo"},
+ }
+
+ result, diags := evalVariableValidation(rule, hclCtx, hcl.Range{}, varAddr, 0)
+ if got, want := result.Status, checks.StatusError; got != want {
+ t.Errorf("wrong result.Status\ngot: %s\nwant: %s", got, want)
+ }
+ if !diags.HasErrors() {
+ t.Fatalf("unexpected success; want error")
+ }
+ found := false
+ hasCorrectExtra := false
+ wantDesc := tfdiags.Description{
+ Summary: "Invalid error message",
+ Detail: "Unsuitable value for error message: expression refers to values that won't be known until the apply phase.",
+ }
+ for _, diag := range diags {
+ gotDesc := diag.Description()
+ if diag.Severity() == tfdiags.Error && gotDesc.Summary == wantDesc.Summary && gotDesc.Detail == wantDesc.Detail {
+ found = true
+ hasCorrectExtra = tfdiags.DiagnosticCausedByUnknown(diag)
+ break
+ }
+ }
+ if !found {
+ t.Errorf("missing expected error diagnostic\nwant: %s: %s\ngot: %s",
+ wantDesc.Summary, wantDesc.Detail,
+ diags.Err().Error(),
+ )
+ } else if !hasCorrectExtra {
+ t.Errorf("diagnostic is not marked as being 'caused by unknown'")
+ }
+ })
+}