coder · mtojek · Mar 7, 2023 · Mar 7, 2023 · Mar 7, 2023 · Mar 7, 2023
diff --git a/docs/data-sources/parameter.md b/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.
 - `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) The name of the Terraform variable used by legacy parameters. Coder will use it to lookup the parameter value.
 - `mutable` (Boolean) Whether this value can be changed after workspace creation. This can be destructive for values like region, so use with caution!
 - `option` (Block List, Max: 64) Each "option" block defines a value for a user to select from. (see [below for nested schema](#nestedblock--option))
 - `type` (String) The type of this parameter. Must be one of: "number", "string", or "bool".

diff --git a/examples/resources/coder_parameter/resource.tf b/examples/resources/coder_parameter/resource.tf
@@ -74,4 +74,4 @@ data "coder_parameter" "cat_lives" {
 data "coder_parameter" "fairy_tale" {
   name = "Fairy Tale"
   type = "string"
-}
+}
diff --git a/examples/resources/coder_parameter_migration/resource.tf b/examples/resources/coder_parameter_migration/resource.tf
@@ -0,0 +1,12 @@
+provider "coder" {}
+
+variable "old_account_name" {
+  type    = string
+  default = "fake-user" # for testing purposes, no need to set via env TF_...
+}
+
+data "coder_parameter" "account_name" {
+  name            = "Account Name"
+  type            = "string"
+  legacy_variable = var.old_account_name
+}
diff --git a/provider/examples_test.go b/provider/examples_test.go
@@ -14,6 +14,8 @@ func TestExamples(t *testing.T) {
 	t.Parallel()
 
 	t.Run("coder_parameter", func(t *testing.T) {
+		t.Parallel()
+
 		resource.Test(t, resource.TestCase{
 			Providers: map[string]*schema.Provider{
 				"coder": provider.New(),
@@ -24,6 +26,20 @@ func TestExamples(t *testing.T) {
 			}},
 		})
 	})
+
+	t.Run("coder_parameter_migration", func(t *testing.T) {
+		t.Parallel()
+
+		resource.Test(t, resource.TestCase{
+			Providers: map[string]*schema.Provider{
+				"coder": provider.New(),
+			},
+			IsUnitTest: true,
+			Steps: []resource.TestStep{{
+				Config: mustReadFile(t, "../examples/resources/coder_parameter_migration/resource.tf"),
+			}},
+		})
+	})
 }
 
 func mustReadFile(t *testing.T, path string) string {

diff --git a/provider/parameter.go b/provider/parameter.go
@@ -49,6 +49,8 @@ type Parameter struct {
 	Option      []Option
 	Validation  []Validation
 	Optional    bool
+
+	LegacyVariable string
 }
 
 func parameterDataSource() *schema.Resource {
@@ -69,16 +71,28 @@ func parameterDataSource() *schema.Resource {
 				Option      interface{}
 				Validation  interface{}
 				Optional    interface{}
+
+				LegacyVariable interface{}
 			}{
 				Value:       rd.Get("value"),
 				Name:        rd.Get("name"),
 				Description: rd.Get("description"),
 				Type:        rd.Get("type"),
 				Mutable:     rd.Get("mutable"),
-				Default:     rd.Get("default"),
-				Icon:        rd.Get("icon"),
-				Option:      rd.Get("option"),
-				Validation:  rd.Get("validation"),
+				Default: func() interface{} {
+					standardMode := rd.GetRawConfig().AsValueMap()["legacy_variable"].IsNull()
+					if standardMode {
+						return rd.Get("default")
+					}
+
+					// legacy variable is linked
+					legacyVariable := rd.GetRawConfig().AsValueMap()["legacy_variable"].AsString()
+					rd.Set("default", legacyVariable)
+					return legacyVariable
+				}(),
+				Icon:       rd.Get("icon"),
+				Option:     rd.Get("option"),
+				Validation: rd.Get("validation"),
 				Optional: func() bool {
 					// This hack allows for checking if the "default" field is present in the .tf file.
 					// If "default" is missing or is "null", then it means that this field is required,
@@ -87,6 +101,7 @@ func parameterDataSource() *schema.Resource {
 					rd.Set("optional", val)
 					return val
 				}(),
+				LegacyVariable: rd.Get("legacy_variable"),
 			}, &parameter)
 			if err != nil {
 				return diag.Errorf("decode parameter: %s", err)
@@ -282,6 +297,11 @@ func parameterDataSource() *schema.Resource {
 				Computed:    true,
 				Description: "Whether this value is optional.",
 			},
+			"legacy_variable": {
+				Type:        schema.TypeString,
+				Optional:    true,
+				Description: "The name of the Terraform variable used by legacy parameters. Coder will use it to lookup the parameter value.",
+			},
 		},
 	}
 }