feat: support ephemeral parameters (#138)

Author: mtojek

Diff for: docs/data-sources/parameter.md

@@ -24,6 +24,7 @@ Use this data source to configure editable options for workspaces.
 - `default` (String) A default value for the parameter.
 - `description` (String) Describe what this parameter does.
 - `display_name` (String) The displayed name of the parameter as it will appear in the interface.
+- `ephemeral` (Boolean) The value of an ephemeral parameter will not be preserved between consecutive workspace builds.
 - `icon` (String) A URL to an icon that will display in the dashboard. View built-in icons here: https://github.com/coder/coder/tree/main/site/static/icon. Use a built-in icon with `data.coder_workspace.me.access_url + "/icon/<path>"`.
 - `legacy_variable` (String, Deprecated) Reference to the Terraform variable. Coder will use it to lookup the default value.
 - `legacy_variable_name` (String, Deprecated) Name of the legacy Terraform variable. Coder will use it to lookup the variable value.

Diff for: examples/resources/coder_parameter/resource.tf

@@ -74,8 +74,10 @@ data "coder_parameter" "cat_lives" {
 }
 
 data "coder_parameter" "fairy_tale" {
-  name = "Fairy Tale"
-  type = "string"
+  name      = "Fairy Tale"
+  type      = "string"
+  mutable   = true
+  ephemeral = true
 }
 
 data "coder_parameter" "users" {

Diff for: provider/parameter.go

@@ -56,8 +56,8 @@ type Parameter struct {
 	Option      []Option
 	Validation  []Validation
 	Optional    bool
-
-	Order int
+	Order       int
+	Ephemeral   bool
 
 	LegacyVariableName string `mapstructure:"legacy_variable_name"`
 	LegacyVariable     string `mapstructure:"legacy_variable"`
@@ -93,6 +93,7 @@ func parameterDataSource() *schema.Resource {
 				Validation  interface{}
 				Optional    interface{}
 				Order       interface{}
+				Ephemeral   interface{}
 
 				LegacyVariableName interface{}
 				LegacyVariable     interface{}
@@ -126,6 +127,7 @@ func parameterDataSource() *schema.Resource {
 					return val
 				}(),
 				Order:              rd.Get("order"),
+				Ephemeral:          rd.Get("ephemeral"),
 				LegacyVariableName: rd.Get("legacy_variable_name"),
 				LegacyVariable:     rd.Get("legacy_variable"),
 			}, &parameter)
@@ -146,6 +148,10 @@ func parameterDataSource() *schema.Resource {
 			}
 			rd.Set("value", value)
 
+			if !parameter.Mutable && parameter.Ephemeral {
+				return diag.Errorf("parameter can't be immutable and ephemeral")
+			}
+
 			if len(parameter.Validation) == 1 {
 				validation := &parameter.Validation[0]
 				err = validation.Valid(parameter.Type, value)
@@ -340,6 +346,12 @@ func parameterDataSource() *schema.Resource {
 				Optional:    true,
 				Description: "The order determines the position of a template parameter in the UI/CLI presentation. The lowest order is shown first and parameters with equal order are sorted by name (ascending order).",
 			},
+			"ephemeral": {
+				Type:        schema.TypeBool,
+				Default:     false,
+				Optional:    true,
+				Description: "The value of an ephemeral parameter will not be preserved between consecutive workspace builds.",
+			},
 			"legacy_variable_name": {
 				Type:         schema.TypeString,
 				Optional:     true,

Diff for: provider/parameter_test.go

@@ -44,6 +44,7 @@ func TestParameter(t *testing.T) {
 					description = "Select for east!"
 				}
 				order = 5
+				ephemeral = true
 			}
 			`,
 		Check: func(state *terraform.ResourceState) {
@@ -64,6 +65,7 @@ func TestParameter(t *testing.T) {
 				"option.1.icon":        "/icon/east.svg",
 				"option.1.description": "Select for east!",
 				"order":                "5",
+				"ephemeral":            "true",
 			} {
 				require.Equal(t, value, attrs[key])
 			}
@@ -602,6 +604,17 @@ data "coder_parameter" "region" {
 			}
 			`,
 		ExpectError: regexp.MustCompile("a min cannot be specified for a bool type"),
+	}, {
+		Name: "ImmutableEphemeralError",
+		Config: `
+			data "coder_parameter" "region" {
+				name = "Region"
+				type = "string"
+				mutable = false
+				ephemeral = true
+			}
+			`,
+		ExpectError: regexp.MustCompile("parameter can't be immutable and ephemeral"),
 	}} {
 		tc := tc
 		t.Run(tc.Name, func(t *testing.T) {