Merge pull request #38146 from hashicorp/dbanck/variable-const-attribute

Add `const` attribute to variable blocks

internal/configs/module_merge.go

@@ -53,6 +53,10 @@ func (v *Variable) merge(ov *Variable) hcl.Diagnostics {
 		v.Ephemeral = ov.Ephemeral
 		v.EphemeralSet = ov.EphemeralSet
 	}
+	if ov.ConstSet {
+		v.Const = ov.Const
+		v.ConstSet = ov.ConstSet
+	}
 	if ov.Default != cty.NilVal {
 		v.Default = ov.Default
 	}

internal/configs/module_merge_test.go

@@ -308,7 +308,117 @@ func TestModuleOverrideSensitiveVariable(t *testing.T) {
 			}
 
 			if got[v].SensitiveSet != want.sensitiveSet {
-				t.Errorf("wrong result for sensitive set\ngot: %t want: %t", got[v].Sensitive, want.sensitive)
+				t.Errorf("wrong result for sensitive set\ngot: %t want: %t", got[v].SensitiveSet, want.sensitiveSet)
+			}
+		})
+	}
+}
+
+func TestModuleOverrideEphemeralVariable(t *testing.T) {
+	type testCase struct {
+		ephemeral    bool
+		ephemeralSet bool
+	}
+	cases := map[string]testCase{
+		"false_true": {
+			ephemeral:    true,
+			ephemeralSet: true,
+		},
+		"true_false": {
+			ephemeral:    false,
+			ephemeralSet: true,
+		},
+		"false_false_true": {
+			ephemeral:    true,
+			ephemeralSet: true,
+		},
+		"true_true_false": {
+			ephemeral:    false,
+			ephemeralSet: true,
+		},
+		"false_true_false": {
+			ephemeral:    false,
+			ephemeralSet: true,
+		},
+		"true_false_true": {
+			ephemeral:    true,
+			ephemeralSet: true,
+		},
+	}
+
+	mod, diags := testModuleFromDir("testdata/valid-modules/override-variable-ephemeral")
+
+	assertNoDiagnostics(t, diags)
+
+	if mod == nil {
+		t.Fatalf("module is nil")
+	}
+
+	got := mod.Variables
+
+	for v, want := range cases {
+		t.Run(fmt.Sprintf("variable %s", v), func(t *testing.T) {
+			if got[v].Ephemeral != want.ephemeral {
+				t.Errorf("wrong result for ephemeral\ngot: %t want: %t", got[v].Ephemeral, want.ephemeral)
+			}
+
+			if got[v].EphemeralSet != want.ephemeralSet {
+				t.Errorf("wrong result for ephemeral set\ngot: %t want: %t", got[v].EphemeralSet, want.ephemeralSet)
+			}
+		})
+	}
+}
+
+func TestModuleOverrideConstVariable(t *testing.T) {
+	type testCase struct {
+		constV   bool
+		constSet bool
+	}
+	cases := map[string]testCase{
+		"false_true": {
+			constV:   true,
+			constSet: true,
+		},
+		"true_false": {
+			constV:   false,
+			constSet: true,
+		},
+		"false_false_true": {
+			constV:   true,
+			constSet: true,
+		},
+		"true_true_false": {
+			constV:   false,
+			constSet: true,
+		},
+		"false_true_false": {
+			constV:   false,
+			constSet: true,
+		},
+		"true_false_true": {
+			constV:   true,
+			constSet: true,
+		},
+	}
+
+	mod, diags := testModuleFromDir("testdata/valid-modules/override-variable-const")
+
+	assertNoDiagnostics(t, diags)
+
+	if mod == nil {
+		t.Fatalf("module is nil")
+	}
+
+	got := mod.Variables
+
+	for v, want := range cases {
+		t.Run(fmt.Sprintf("variable %s", v), func(t *testing.T) {
+			if got[v].Const != want.constV {
+				t.Errorf("wrong result for const\ngot: %t want: %t", got[v].Const, want.constV)
+			}
+
+			if got[v].ConstSet != want.constSet {
+				t.Errorf("wrong result for const set\ngot: %t want: %t", got[v].ConstSet, want.constSet)
 			}
 		})
 	}

internal/configs/named_values.go

@@ -38,9 +38,14 @@ type Variable struct {
 	Sensitive   bool
 	Ephemeral   bool
 
+	// Const indicates that this variable can be used during early evaluation
+	// work and configuration loading, for example in module sources
+	Const bool
+
 	DescriptionSet bool
 	SensitiveSet   bool
 	EphemeralSet   bool
+	ConstSet       bool
 
 	// Nullable indicates that null is a valid value for this variable. Setting
 	// Nullable to false means that the module can expect this variable to
@@ -133,6 +138,12 @@ func decodeVariableBlock(block *hcl.Block, override bool) (*Variable, hcl.Diagno
 		v.EphemeralSet = true
 	}
 
+	if attr, exists := content.Attributes["const"]; exists {
+		valDiags := gohcl.DecodeExpression(attr.Expr, nil, &v.Const)
+		diags = append(diags, valDiags...)
+		v.ConstSet = true
+	}
+
 	if attr, exists := content.Attributes["nullable"]; exists {
 		valDiags := gohcl.DecodeExpression(attr.Expr, nil, &v.Nullable)
 		diags = append(diags, valDiags...)
@@ -525,6 +536,9 @@ var variableBlockSchema = &hcl.BodySchema{
 		{
 			Name: "deprecated",
 		},
+		{
+			Name: "const",
+		},
 	},
 	Blocks: []hcl.BlockHeaderSchema{
 		{

internal/configs/testdata/valid-modules/override-variable-const/a_override.tf

@@ -0,0 +1,23 @@
+variable "false_true" {
+  const = true
+}
+
+variable "true_false" {
+  const = false
+}
+
+variable "false_false_true" {
+  const = false
+}
+
+variable "true_true_false" {
+  const = true
+}
+
+variable "false_true_false" {
+  const = true
+}
+
+variable "true_false_true" {
+  const = false
+}

internal/configs/testdata/valid-modules/override-variable-const/b_override.tf

@@ -0,0 +1,21 @@
+variable "false_true" {
+}
+
+variable "true_false" {
+}
+
+variable "false_false_true" {
+  const = true
+}
+
+variable "true_true_false" {
+  const = false
+}
+
+variable "false_true_false" {
+  const = false
+}
+
+variable "true_false_true" {
+  const = true
+}

internal/configs/testdata/valid-modules/override-variable-const/primary.tf

@@ -0,0 +1,23 @@
+variable "false_true" {
+  const = false
+}
+
+variable "true_false" {
+  const = true
+}
+
+variable "false_false_true" {
+  const = false
+}
+
+variable "true_true_false" {
+  const = true
+}
+
+variable "false_true_false" {
+  const = false
+}
+
+variable "true_false_true" {
+  const = true
+}

internal/configs/testdata/valid-modules/override-variable-ephemeral/a_override.tf

@@ -0,0 +1,23 @@
+variable "false_true" {
+  ephemeral = true
+}
+
+variable "true_false" {
+  ephemeral = false
+}
+
+variable "false_false_true" {
+  ephemeral = false
+}
+
+variable "true_true_false" {
+  ephemeral = true
+}
+
+variable "false_true_false" {
+  ephemeral = true
+}
+
+variable "true_false_true" {
+  ephemeral = false
+}

internal/configs/testdata/valid-modules/override-variable-ephemeral/b_override.tf

@@ -0,0 +1,21 @@
+variable "false_true" {
+}
+
+variable "true_false" {
+}
+
+variable "false_false_true" {
+  ephemeral = true
+}
+
+variable "true_true_false" {
+  ephemeral = false
+}
+
+variable "false_true_false" {
+  ephemeral = false
+}
+
+variable "true_false_true" {
+  ephemeral = true
+}

internal/configs/testdata/valid-modules/override-variable-ephemeral/primary.tf

@@ -0,0 +1,23 @@
+variable "false_true" {
+  ephemeral = false
+}
+
+variable "true_false" {
+  ephemeral = true
+}
+
+variable "false_false_true" {
+  ephemeral = false
+}
+
+variable "true_true_false" {
+  ephemeral = true
+}
+
+variable "false_true_false" {
+  ephemeral = false
+}
+
+variable "true_false_true" {
+  ephemeral = true
+}