Sort tasks by `task_key` before generating the Terraform configuration (#1776)

## Changes
Sort the tasks in the resultant `bundle.tf.json`. This is important
because configuration from one task can leak into another if the tasks
are not sorted.

For more details see:
1.
https://github.com/databricks/terraform-provider-databricks/issues/3951
2.
https://github.com/databricks/terraform-provider-databricks/issues/4011

## Tests
Unit test and manually.

For manual testing I used the following configuration:
```
resources:
  jobs:
    foo:
      tasks: 
        - task_key: task-Z
          notebook_task: 
            notebook_path: nb.py
            source: GIT
          existing_cluster_id: 0715-133738-ju0ma84z

        - task_key: task-1
          notebook_task: 
            notebook_path: ${workspace.file_path}/local.py
            source: WORKSPACE
          existing_cluster_id: 0715-133738-ju0ma84z
          depends_on: 
            - task_key: task-Z


      git_source: 
        git_provider: gitHub
        git_url: https://github.com/shreyas-goenka/job-source-tmp.git
        git_branch: main
```

Steps (1):
1. Deploy this bundle.
2. Comment out "source: GIT"
3. Deploy again

Before:
Deploying this bundle twice would fail. This is because the "source:
GIT" would carry over to the next deployment.

After:
There was no error on the subsequent deployment.

Steps (2):
1. Deploy once
2. Deploy again

Before:
Works correctly but leads to a update API call every time.

After:
No diff is detected by terraform.

bundle/config/root.go

@@ -406,7 +406,14 @@ func (r *Root) MergeTargetOverrides(name string) error {
 	return r.updateWithDynamicValue(root)
 }
 
-var variableKeywords = []string{"default", "lookup"}
+var allowedVariableDefinitions = []([]string){
+	{"default", "type", "description"},
+	{"default", "type"},
+	{"default", "description"},
+	{"lookup", "description"},
+	{"default"},
+	{"lookup"},
+}
 
 // isFullVariableOverrideDef checks if the given value is a full syntax varaible override.
 // A full syntax variable override is a map with either 1 of 2 keys.
@@ -423,42 +430,21 @@ func isFullVariableOverrideDef(v dyn.Value) bool {
 		return false
 	}
 
-	// If the map has 3 keys, they should be "description", "type" and "default" or "lookup"
-	if mv.Len() == 3 {
-		if _, ok := mv.GetByString("type"); ok {
-			if _, ok := mv.GetByString("description"); ok {
-				if _, ok := mv.GetByString("default"); ok {
-					return true
-				}
+	for _, keys := range allowedVariableDefinitions {
+		if len(keys) != mv.Len() {
+			continue
+		}
+
+		// Check if the keys are the same.
+		match := true
+		for _, key := range keys {
+			if _, ok := mv.GetByString(key); !ok {
+				match = false
+				break
 			}
 		}
 
-		return false
-	}
-
-	// If the map has 2 keys, one of them should be "default" or "lookup" and the other is "type" or "description"
-	if mv.Len() == 2 {
-		if _, ok := mv.GetByString("type"); ok {
-			if _, ok := mv.GetByString("default"); ok {
-				return true
-			}
-		}
-
-		if _, ok := mv.GetByString("description"); ok {
-			if _, ok := mv.GetByString("default"); ok {
-				return true
-			}
-
-			if _, ok := mv.GetByString("lookup"); ok {
-				return true
-			}
-		}
-
-		return false
-	}
-
-	for _, keyword := range variableKeywords {
-		if _, ok := mv.GetByString(keyword); ok {
+		if match {
 			return true
 		}
 	}

bundle/deploy/terraform/convert.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"sort"
 
 	"github.com/databricks/cli/bundle/config"
 	"github.com/databricks/cli/bundle/config/resources"
@@ -82,6 +83,10 @@ func BundleToTerraform(config *config.Root) *schema.Root {
 		conv(src, &dst)
 
 		if src.JobSettings != nil {
+			sort.Slice(src.JobSettings.Tasks, func(i, j int) bool {
+				return src.JobSettings.Tasks[i].TaskKey < src.JobSettings.Tasks[j].TaskKey
+			})
+
 			for _, v := range src.Tasks {
 				var t schema.ResourceJobTask
 				conv(v, &t)

bundle/deploy/terraform/tfdyn/convert_job.go

@@ -3,6 +3,7 @@ package tfdyn
 import (
 	"context"
 	"fmt"
+	"sort"
 
 	"github.com/databricks/cli/bundle/internal/tf/schema"
 	"github.com/databricks/cli/libs/dyn"
@@ -19,8 +20,38 @@ func convertJobResource(ctx context.Context, vin dyn.Value) (dyn.Value, error) {
 		log.Debugf(ctx, "job normalization diagnostic: %s", diag.Summary)
 	}
 
+	// Sort the tasks of each job in the bundle by task key. Sorting
+	// the task keys ensures that the diff computed by terraform is correct and avoids
+	// recreates. For more details see the NOTE at
+	// https://registry.terraform.io/providers/databricks/databricks/latest/docs/resources/job#example-usage
+	// and https://github.com/databricks/terraform-provider-databricks/issues/4011
+	// and https://github.com/databricks/cli/pull/1776
+	vout := vin
+	var err error
+	tasks, ok := vin.Get("tasks").AsSequence()
+	if ok {
+		sort.Slice(tasks, func(i, j int) bool {
+			// We sort the tasks by their task key. Tasks without task keys are ordered
+			// before tasks with task keys. We do not error for those tasks
+			// since presence of a task_key is validated for in the Jobs backend.
+			tk1, ok := tasks[i].Get("task_key").AsString()
+			if !ok {
+				return true
+			}
+			tk2, ok := tasks[j].Get("task_key").AsString()
+			if !ok {
+				return false
+			}
+			return tk1 < tk2
+		})
+		vout, err = dyn.Set(vin, "tasks", dyn.V(tasks))
+		if err != nil {
+			return dyn.InvalidValue, err
+		}
+	}
+
 	// Modify top-level keys.
-	vout, err := renameKeys(vin, map[string]string{
+	vout, err = renameKeys(vout, map[string]string{
 		"tasks":        "task",
 		"job_clusters": "job_cluster",
 		"parameters":   "parameter",

bundle/deploy/terraform/tfdyn/convert_job_test.go

@@ -42,8 +42,8 @@ func TestConvertJob(t *testing.T) {
 			},
 			Tasks: []jobs.Task{
 				{
-					TaskKey:       "task_key",
-					JobClusterKey: "job_cluster_key",
+					TaskKey:       "task_key_b",
+					JobClusterKey: "job_cluster_key_b",
 					Libraries: []compute.Library{
 						{
 							Pypi: &compute.PythonPyPiLibrary{
@@ -55,6 +55,17 @@ func TestConvertJob(t *testing.T) {
 						},
 					},
 				},
+				{
+					TaskKey:       "task_key_a",
+					JobClusterKey: "job_cluster_key_a",
+				},
+				{
+					TaskKey:       "task_key_c",
+					JobClusterKey: "job_cluster_key_c",
+				},
+				{
+					Description: "missing task key 😱",
+				},
 			},
 		},
 		Permissions: []resources.Permission{
@@ -100,8 +111,15 @@ func TestConvertJob(t *testing.T) {
 		},
 		"task": []any{
 			map[string]any{
-				"task_key":        "task_key",
-				"job_cluster_key": "job_cluster_key",
+				"description": "missing task key 😱",
+			},
+			map[string]any{
+				"task_key":        "task_key_a",
+				"job_cluster_key": "job_cluster_key_a",
+			},
+			map[string]any{
+				"task_key":        "task_key_b",
+				"job_cluster_key": "job_cluster_key_b",
 				"library": []any{
 					map[string]any{
 						"pypi": map[string]any{
@@ -113,6 +131,10 @@ func TestConvertJob(t *testing.T) {
 					},
 				},
 			},
+			map[string]any{
+				"task_key":        "task_key_c",
+				"job_cluster_key": "job_cluster_key_c",
+			},
 		},
 	}, out.Job["my_job"])