Use precomputed terraform plan for bundle deploy

bundle/deploy/terraform/apply.go

@@ -4,7 +4,6 @@ import (
 	"context"
 
 	"github.com/databricks/cli/bundle"
-	"github.com/databricks/cli/libs/cmdio"
 	"github.com/databricks/cli/libs/diag"
 	"github.com/databricks/cli/libs/log"
 	"github.com/hashicorp/terraform-exec/tfexec"
@@ -17,28 +16,32 @@ func (w *apply) Name() string {
 }
 
 func (w *apply) Apply(ctx context.Context, b *bundle.Bundle) diag.Diagnostics {
+	// return early if plan is empty
+	if b.Plan.IsEmpty {
+		log.Debugf(ctx, "No changes in plan. Skipping terraform apply.")
+		return nil
+	}
+
 	tf := b.Terraform
 	if tf == nil {
 		return diag.Errorf("terraform not initialized")
 	}
 
-	cmdio.LogString(ctx, "Deploying resources...")
-
-	err := tf.Init(ctx, tfexec.Upgrade(true))
-	if err != nil {
-		return diag.Errorf("terraform init: %v", err)
+	if b.Plan.Path == "" {
+		return diag.Errorf("no plan found")
 	}
 
-	err = tf.Apply(ctx)
+	// Apply terraform according to the computed plan
+	err := tf.Apply(ctx, tfexec.DirOrPlan(b.Plan.Path))
 	if err != nil {
 		return diag.Errorf("terraform apply: %v", err)
 	}
 
-	log.Infof(ctx, "Resource deployment completed")
+	log.Infof(ctx, "terraform apply completed")
 	return nil
 }
 
-// Apply returns a [bundle.Mutator] that runs the equivalent of `terraform apply`
+// Apply returns a [bundle.Mutator] that runs the equivalent of `terraform apply ./plan`
 // from the bundle's ephemeral working directory for Terraform.
 func Apply() bundle.Mutator {
 	return &apply{}

bundle/deploy/terraform/state_push.go

@@ -2,6 +2,8 @@ package terraform
 
 import (
 	"context"
+	"errors"
+	"io/fs"
 	"os"
 	"path/filepath"
 
@@ -34,6 +36,12 @@ func (l *statePush) Apply(ctx context.Context, b *bundle.Bundle) diag.Diagnostic
 
 	// Expect the state file to live under dir.
 	local, err := os.Open(filepath.Join(dir, TerraformStateFileName))
+	if errors.Is(err, fs.ErrNotExist) {
+		// The state file can be absent if terraform apply is skipped because
+		// there are no changes to apply in the plan.
+		log.Debugf(ctx, "Local terraform state file does not exist.")
+		return nil
+	}
 	if err != nil {
 		return diag.FromErr(err)
 	}

bundle/phases/deploy.go

@@ -92,7 +92,10 @@ func Deploy() bundle.Mutator {
 	// Core mutators that CRUD resources and modify deployment state. These
 	// mutators need informed consent if they are potentially destructive.
 	deployCore := bundle.Defer(
-		terraform.Apply(),
+		bundle.Seq(
+			bundle.LogString("Deploying resources..."),
+			terraform.Apply(),
+		),
 		bundle.Seq(
 			terraform.StatePush(),
 			terraform.Load(),

bundle/phases/destroy.go

@@ -82,7 +82,7 @@ func approvalForDestroy(ctx context.Context, b *bundle.Bundle) (bool, error) {
 func Destroy() bundle.Mutator {
 	// Core destructive mutators for destroy. These require informed user consent.
 	destroyCore := bundle.Seq(
-		terraform.Destroy(),
+		terraform.Apply(),
 		terraform.StatePush(),
 		files.Delete(),
 		bundle.LogString("Destroy complete!"),