feat(coderd): support ephemeral parameters (#8367)

codersdk/richparameters.go

@@ -148,8 +148,8 @@ func (r *ParameterResolver) ValidateResolve(p TemplateVersionParameter, v *Works
 	}
 	// First, the provided value
 	resolvedValue := v
-	// Second, previous value
-	if resolvedValue == nil {
+	// Second, previous value if not ephemeral
+	if resolvedValue == nil && !p.Ephemeral {
 		resolvedValue = prevV
 	}
 	// Last, default value

codersdk/richparameters_test.go

@@ -304,3 +304,89 @@ func TestRichParameterValidation(t *testing.T) {
 		}
 	})
 }
+
+func TestParameterResolver_ValidateResolve_Ephemeral_OverridePrevious(t *testing.T) {
+	t.Parallel()
+	uut := codersdk.ParameterResolver{
+		Rich: []codersdk.WorkspaceBuildParameter{{Name: "n", Value: "5"}},
+	}
+	p := codersdk.TemplateVersionParameter{
+		Name:      "n",
+		Type:      "number",
+		Mutable:   true,
+		Required:  true,
+		Ephemeral: true,
+	}
+	v, err := uut.ValidateResolve(p, &codersdk.WorkspaceBuildParameter{
+		Name:  "n",
+		Value: "6",
+	})
+	require.NoError(t, err)
+	require.Equal(t, "6", v)
+}
+
+func TestParameterResolver_ValidateResolve_Ephemeral_FirstTime(t *testing.T) {
+	t.Parallel()
+	uut := codersdk.ParameterResolver{}
+	p := codersdk.TemplateVersionParameter{
+		Name:      "n",
+		Type:      "number",
+		Mutable:   true,
+		Required:  true,
+		Ephemeral: true,
+	}
+	v, err := uut.ValidateResolve(p, &codersdk.WorkspaceBuildParameter{
+		Name:  "n",
+		Value: "6",
+	})
+	require.NoError(t, err)
+	require.Equal(t, "6", v)
+}
+
+func TestParameterResolver_ValidateResolve_Ephemeral_UseDefault(t *testing.T) {
+	t.Parallel()
+	uut := codersdk.ParameterResolver{}
+	p := codersdk.TemplateVersionParameter{
+		Name:         "n",
+		Type:         "number",
+		Mutable:      true,
+		DefaultValue: "5",
+		Ephemeral:    true,
+	}
+	v, err := uut.ValidateResolve(p, nil)
+	require.NoError(t, err)
+	require.Equal(t, "5", v)
+}
+
+func TestParameterResolver_ValidateResolve_Ephemeral_UseEmptyDefault(t *testing.T) {
+	t.Parallel()
+	uut := codersdk.ParameterResolver{}
+	p := codersdk.TemplateVersionParameter{
+		Name:         "n",
+		Type:         "number",
+		Mutable:      true,
+		DefaultValue: "",
+		Ephemeral:    true,
+	}
+	v, err := uut.ValidateResolve(p, nil)
+	require.NoError(t, err)
+	require.Equal(t, "", v)
+}
+
+func TestParameterResolver_ValidateResolve_Ephemeral_RequiredButMissing(t *testing.T) {
+	t.Parallel()
+	uut := codersdk.ParameterResolver{}
+	p := codersdk.TemplateVersionParameter{
+		Name:      "n",
+		Type:      "number",
+		Mutable:   true,
+		Required:  true,
+		Ephemeral: true,
+	}
+	// It is more theoretical than practical case. Schema allows to configure a parameter,
+	// which always requires from initiator to provide the value, but it is not persisted between
+	// consecutive workspace builds.
+	v, err := uut.ValidateResolve(p, nil)
+	require.Error(t, err) // Parameter is required, but not provided.
+	require.Equal(t, "", v)
+}

codersdk/templateversions.go

@@ -63,6 +63,7 @@ type TemplateVersionParameter struct {
 	ValidationMax        *int32                           `json:"validation_max,omitempty"`
 	ValidationMonotonic  ValidationMonotonicOrder         `json:"validation_monotonic,omitempty" enums:"increasing,decreasing"`
 	Required             bool                             `json:"required"`
+	Ephemeral            bool                             `json:"ephemeral"`
 }
 
 // TemplateVersionParameterOption represents a selectable option for a template parameter.