[Feature] Add no_compute attribute to databricks_app (#4364)

## Changes
Support `no_compute` flag for Apps. The flag is only used on create to
determine whether compute should be provisioned as part of the Create
App RPC. Changes to this flag for existing resources are no-ops and
simply propagated from plan to state.

## Tests
<!-- 
How is this tested? Please see the checklist below and also describe any
other relevant tests
-->

- [ ] `make test` run locally
- [ ] relevant change in `docs/` folder
- [ ] covered with integration tests in `internal/acceptance`
- [ ] using Go SDK
- [ ] using TF Plugin Framework

---------

Co-authored-by: Tanmay Rustagi <[email protected]>
Co-authored-by: Tanmay Rustagi <[email protected]>

Author: mgyucht

internal/providers/pluginfw/products/app/resource_app.go

@@ -2,8 +2,11 @@ package app
 
 import (
 	"context"
+	"fmt"
 
+	"github.com/databricks/databricks-sdk-go"
 	"github.com/databricks/databricks-sdk-go/apierr"
+	"github.com/databricks/databricks-sdk-go/retries"
 	"github.com/databricks/databricks-sdk-go/service/apps"
 	"github.com/databricks/terraform-provider-databricks/common"
 	pluginfwcommon "github.com/databricks/terraform-provider-databricks/internal/providers/pluginfw/common"
@@ -14,14 +17,27 @@ import (
 	"github.com/hashicorp/terraform-plugin-framework-validators/objectvalidator"
 	"github.com/hashicorp/terraform-plugin-framework/path"
 	"github.com/hashicorp/terraform-plugin-framework/resource"
+	"github.com/hashicorp/terraform-plugin-framework/resource/schema/int64planmodifier"
 	"github.com/hashicorp/terraform-plugin-framework/resource/schema/stringplanmodifier"
+	"github.com/hashicorp/terraform-plugin-framework/types"
 )
 
 const (
 	resourceName       = "app"
 	resourceNamePlural = "apps"
 )
 
+type appResource struct {
+	apps_tf.App
+	NoCompute types.Bool `tfsdk:"no_compute"`
+}
+
+func (a appResource) ApplySchemaCustomizations(s map[string]tfschema.AttributeBuilder) map[string]tfschema.AttributeBuilder {
+	s["no_compute"] = s["no_compute"].SetOptional()
+	s = apps_tf.App{}.ApplySchemaCustomizations(s)
+	return s
+}
+
 func ResourceApp() resource.Resource {
 	return &resourceApp{}
 }
@@ -35,14 +51,24 @@ func (a resourceApp) Metadata(ctx context.Context, req resource.MetadataRequest,
 }
 
 func (a resourceApp) Schema(ctx context.Context, req resource.SchemaRequest, resp *resource.SchemaResponse) {
-	resp.Schema = tfschema.ResourceStructToSchema(ctx, apps_tf.App{}, func(cs tfschema.CustomizableSchema) tfschema.CustomizableSchema {
+	resp.Schema = tfschema.ResourceStructToSchema(ctx, appResource{}, func(cs tfschema.CustomizableSchema) tfschema.CustomizableSchema {
 		cs.AddPlanModifier(stringplanmodifier.RequiresReplace(), "name")
 		exclusiveFields := []string{"job", "secret", "serving_endpoint", "sql_warehouse"}
 		paths := path.Expressions{}
 		for _, field := range exclusiveFields[1:] {
 			paths = append(paths, path.MatchRelative().AtParent().AtName(field))
 		}
 		cs.AddValidator(objectvalidator.ExactlyOneOf(paths...), "resources", exclusiveFields[0])
+		for _, field := range []string{
+			"create_time",
+			"creator",
+			"service_principal_client_id",
+			"service_principal_name",
+			"url",
+		} {
+			cs.AddPlanModifier(stringplanmodifier.UseStateForUnknown(), field)
+		}
+		cs.AddPlanModifier(int64planmodifier.UseStateForUnknown(), "service_principal_id")
 		return cs
 	})
 }
@@ -61,7 +87,7 @@ func (a *resourceApp) Create(ctx context.Context, req resource.CreateRequest, re
 		return
 	}
 
-	var app apps_tf.App
+	var app appResource
 	resp.Diagnostics.Append(req.Plan.Get(ctx, &app)...)
 	if resp.Diagnostics.HasError() {
 		return
@@ -73,30 +99,39 @@ func (a *resourceApp) Create(ctx context.Context, req resource.CreateRequest, re
 	}
 
 	// Create the app
-	waiter, err := w.Apps.Create(ctx, apps.CreateAppRequest{App: &appGoSdk})
+	var forceSendFields []string
+	if !app.NoCompute.IsNull() {
+		forceSendFields = append(forceSendFields, "NoCompute")
+	}
+	waiter, err := w.Apps.Create(ctx, apps.CreateAppRequest{
+		App:             &appGoSdk,
+		NoCompute:       app.NoCompute.ValueBool(),
+		ForceSendFields: forceSendFields,
+	})
 	if err != nil {
 		resp.Diagnostics.AddError("failed to create app", err.Error())
 		return
 	}
 
 	// Store the initial version of the app in state
-	var newApp apps_tf.App
+	var newApp appResource
 	resp.Diagnostics.Append(converters.GoSdkToTfSdkStruct(ctx, waiter.Response, &newApp)...)
 	if resp.Diagnostics.HasError() {
 		return
 	}
+	newApp.NoCompute = app.NoCompute
 	resp.Diagnostics.Append(resp.State.Set(ctx, newApp)...)
 	if resp.Diagnostics.HasError() {
 		return
 	}
 
-	// Wait for the app to be created
-	finalApp, err := waiter.Get()
+	// Wait for the app to be created. If no_compute is specified, the terminal state is
+	// STOPPED, otherwise it is ACTIVE.
+	finalApp, err := a.waitForApp(ctx, w, appGoSdk.Name)
 	if err != nil {
-		resp.Diagnostics.AddError("error waiting for app to be ready", err.Error())
+		resp.Diagnostics.AddError("error waiting for app to be active or stopped", err.Error())
 		return
 	}
-
 	// Store the final version of the app in state
 	resp.Diagnostics.Append(converters.GoSdkToTfSdkStruct(ctx, finalApp, &newApp)...)
 	if resp.Diagnostics.HasError() {
@@ -108,6 +143,43 @@ func (a *resourceApp) Create(ctx context.Context, req resource.CreateRequest, re
 	}
 }
 
+// This is copied from the retries package of the databricks-sdk-go. It should be made public,
+// but for now, I'm copying it here.
+func shouldRetry(err error) bool {
+	if err == nil {
+		return false
+	}
+	e := err.(*retries.Err)
+	if e == nil {
+		return false
+	}
+	return !e.Halt
+}
+
+// waitForApp waits for the app to reach the target state. The target state is either ACTIVE or STOPPED.
+// Apps with no_compute set to true will reach the STOPPED state, otherwise they will reach the ACTIVE state.
+func (a *resourceApp) waitForApp(ctx context.Context, w *databricks.WorkspaceClient, name string) (*apps.App, error) {
+	retrier := retries.New[apps.App](retries.WithTimeout(-1), retries.WithRetryFunc(shouldRetry))
+	return retrier.Run(ctx, func(ctx context.Context) (*apps.App, error) {
+		app, err := w.Apps.GetByName(ctx, name)
+		if err != nil {
+			return nil, retries.Halt(err)
+		}
+		status := app.ComputeStatus.State
+		statusMessage := app.ComputeStatus.Message
+		switch status {
+		case apps.ComputeStateActive, apps.ComputeStateStopped:
+			return app, nil
+		case apps.ComputeStateError:
+			err := fmt.Errorf("failed to reach %s or %s, got %s: %s",
+				apps.ComputeStateActive, apps.ComputeStateStopped, status, statusMessage)
+			return nil, retries.Halt(err)
+		default:
+			return nil, retries.Continues(statusMessage)
+		}
+	})
+}
+
 func (a *resourceApp) Read(ctx context.Context, req resource.ReadRequest, resp *resource.ReadResponse) {
 	ctx = pluginfwcontext.SetUserAgentInResourceContext(ctx, resourceName)
 	w, diags := a.client.GetWorkspaceClient()
@@ -116,7 +188,7 @@ func (a *resourceApp) Read(ctx context.Context, req resource.ReadRequest, resp *
 		return
 	}
 
-	var app apps_tf.App
+	var app appResource
 	resp.Diagnostics.Append(req.State.Get(ctx, &app)...)
 	if resp.Diagnostics.HasError() {
 		return
@@ -128,11 +200,12 @@ func (a *resourceApp) Read(ctx context.Context, req resource.ReadRequest, resp *
 		return
 	}
 
-	var newApp apps_tf.App
+	var newApp appResource
 	resp.Diagnostics.Append(converters.GoSdkToTfSdkStruct(ctx, appGoSdk, &newApp)...)
 	if resp.Diagnostics.HasError() {
 		return
 	}
+	newApp.NoCompute = app.NoCompute
 	resp.Diagnostics.Append(resp.State.Set(ctx, newApp)...)
 	if resp.Diagnostics.HasError() {
 		return
@@ -147,7 +220,7 @@ func (a *resourceApp) Update(ctx context.Context, req resource.UpdateRequest, re
 		return
 	}
 
-	var app apps_tf.App
+	var app appResource
 	resp.Diagnostics.Append(req.Plan.Get(ctx, &app)...)
 	if resp.Diagnostics.HasError() {
 		return
@@ -166,11 +239,13 @@ func (a *resourceApp) Update(ctx context.Context, req resource.UpdateRequest, re
 	}
 
 	// Store the updated version of the app in state
-	var newApp apps_tf.App
+	var newApp appResource
 	resp.Diagnostics.Append(converters.GoSdkToTfSdkStruct(ctx, response, &newApp)...)
 	if resp.Diagnostics.HasError() {
 		return
 	}
+	// Modifying no_compute after creation has no effect.
+	newApp.NoCompute = app.NoCompute
 	resp.Diagnostics.Append(resp.State.Set(ctx, newApp)...)
 	if resp.Diagnostics.HasError() {
 		return
@@ -185,7 +260,7 @@ func (a *resourceApp) Delete(ctx context.Context, req resource.DeleteRequest, re
 		return
 	}
 
-	var app apps_tf.App
+	var app appResource
 	resp.Diagnostics.Append(req.State.Get(ctx, &app)...)
 	if resp.Diagnostics.HasError() {
 		return

internal/providers/pluginfw/products/app/resource_app_acc_test.go

@@ -55,7 +55,7 @@ const baseResources = `
 func makeTemplate(description string) string {
 	appTemplate := baseResources + `
 	resource "databricks_app" "this" {
-		name = "{var.STICKY_RANDOM}"
+		name = "tf-{var.STICKY_RANDOM}"
 		description = "%s"
 		resources = [{
 			name = "secret"
@@ -93,7 +93,7 @@ func makeTemplate(description string) string {
 
 var templateWithInvalidResource = `
 	resource "databricks_app" "this" {
-		name = "{var.STICKY_RANDOM}"
+		name = "tf-{var.STICKY_RANDOM}"
 		description = "My app"
 		resources = [{
 			name = "invalid resource"
@@ -147,3 +147,42 @@ func TestAccAppResource(t *testing.T) {
 		ImportStateVerifyIdentifierAttribute: "name",
 	})
 }
+
+func TestAccAppResource_NoCompute(t *testing.T) {
+	acceptance.LoadWorkspaceEnv(t)
+	if acceptance.IsGcp(t) {
+		acceptance.Skipf(t)("not available on GCP")
+	}
+	acceptance.WorkspaceLevel(t, acceptance.Step{
+		Template: `
+	resource "databricks_secret_scope" "this" {
+		name = "tf-{var.STICKY_RANDOM}"
+	}
+
+	resource "databricks_secret" "this" {
+	    scope = databricks_secret_scope.this.name
+		key = "tf-{var.STICKY_RANDOM}"
+		string_value = "secret"
+	}
+	resource "databricks_app" "this" {
+		no_compute = true
+		name = "tf-{var.STICKY_RANDOM}"
+		description = "no_compute app"
+		resources = [{
+			name = "secret"
+			description = "secret for app"
+			secret = {
+				scope = databricks_secret_scope.this.name
+				key = databricks_secret.this.key
+				permission = "MANAGE"
+			}
+		}]
+	}
+		`,
+		Check: func(s *terraform.State) error {
+			computeStatus := s.RootModule().Resources["databricks_app.this"].Primary.Attributes["compute_status.state"]
+			assert.Equal(t, "STOPPED", computeStatus)
+			return nil
+		},
+	})
+}