Track bundle resource counts and state file sizes in telemetry

Adds a new typed BundleResourcesMetadata struct under
BundleDeployExperimental, capturing per-resource-type metadata for a
bundle deploy:
- count of resources of each type declared in the bundle configuration
- max, mean, median state size in bytes across resources of that type
- whole state file size on disk
- deployment engine ("direct" or "terraform")

For Terraform deployments the tfstate is translated to the direct-
engine representation (via the existing TerraformToGroupName map) before
sizing so per-type stats are comparable across engines.

The new count field replaces the deprecated DatabricksBundleDeployEvent
.resource_*_count fields; both are populated during the transition.
The Go mirror marks the deprecated Resource*Count fields with a
"// Deprecated:" comment.

Measurement is performed at telemetry-emission time by reading the
on-disk state file once, so this lands as a single isolated module
(bundle/phases/resources_metadata.go) with one new line at the call
site — no instrumentation in deploy mutators, state-mgmt code, or
bundle.Metrics. To remove: delete the new module and revert one line
in telemetry.go plus the proto/Go field.

Requires the new resources_metadata field on BundleDeployExperimental
from the universe PR. Lumberjack drops unknown fields, so the two PRs
can land in either order.

Author: shreyas-goenka

bundle/phases/resources_metadata.go

@@ -0,0 +1,250 @@
+package phases
+
+import (
+	"cmp"
+	"context"
+	"encoding/json"
+	"errors"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"slices"
+	"strings"
+
+	"github.com/databricks/cli/bundle"
+	"github.com/databricks/cli/bundle/deploy/terraform"
+	"github.com/databricks/cli/bundle/direct/dstate"
+	"github.com/databricks/cli/libs/dyn"
+	"github.com/databricks/cli/libs/log"
+	"github.com/databricks/cli/libs/telemetry/protos"
+	tfjson "github.com/hashicorp/terraform-json"
+)
+
+// collectResourcesMetadata builds a BundleResourcesMetadata for the deploy:
+// per-resource-type counts come from the bundle configuration (matching the
+// semantics of the deprecated DatabricksBundleDeployEvent.resource_*_count
+// fields), and state-size statistics come from the on-disk deployment state
+// file. For Terraform deployments the tfstate is translated to the direct-
+// engine representation before sizing so per-type stats are comparable across
+// engines.
+//
+// Returns nil only on a complete absence of signal (no resources declared and
+// no readable state). Telemetry must never fail a deploy — all parse errors
+// are logged at debug level and treated as missing data.
+//
+// This file is the sole site of resource-metadata telemetry logic. To remove
+// the feature: delete this file and its companion test, revert the call site
+// in telemetry.go, and revert the ResourcesMetadata field in
+// libs/telemetry/protos/bundle_deploy.go.
+func collectResourcesMetadata(ctx context.Context, b *bundle.Bundle) *protos.BundleResourcesMetadata {
+	counts := countResourcesByType(ctx, b)
+
+	engine, fileSize, sizesByType := readStateForMetadata(ctx, b)
+
+	if len(counts) == 0 && len(sizesByType) == 0 && fileSize == 0 {
+		return nil
+	}
+
+	types := unionKeys(counts, sizesByType)
+	slices.Sort(types)
+
+	resources := make([]protos.ResourceMetadata, 0, len(types))
+	for _, t := range types {
+		sizes := sizesByType[t]
+		slices.SortFunc(sizes, func(a, b int64) int { return cmp.Compare(a, b) })
+		resources = append(resources, protos.ResourceMetadata{
+			ResourceType:         t,
+			Count:                counts[t],
+			StateSizeMaxBytes:    statMax(sizes),
+			StateSizeMeanBytes:   statMean(sizes),
+			StateSizeMedianBytes: statMedian(sizes),
+		})
+	}
+
+	return &protos.BundleResourcesMetadata{
+		StateEngine:        engine,
+		StateFileSizeBytes: fileSize,
+		Resources:          resources,
+	}
+}
+
+// countResourcesByType walks the bundle config and counts top-level resources
+// at "resources.<type>.<name>". Returns map[type]count.
+func countResourcesByType(ctx context.Context, b *bundle.Bundle) map[string]int64 {
+	out := make(map[string]int64)
+	pattern := dyn.NewPattern(dyn.Key("resources"), dyn.AnyKey(), dyn.AnyKey())
+	_, err := dyn.MapByPattern(b.Config.Value(), pattern, func(p dyn.Path, v dyn.Value) (dyn.Value, error) {
+		if len(p) >= 2 {
+			out[p[1].Key()]++
+		}
+		return v, nil
+	})
+	if err != nil {
+		log.Debugf(ctx, "resources-metadata telemetry: failed to walk config resources: %s", err)
+	}
+	return out
+}
+
+// readStateForMetadata reads whichever local state file exists (direct
+// preferred, then terraform) and returns engine name, whole-file size, and
+// per-resource-type sizes. Returns ("", 0, nil) if no state is present or if
+// the bundle isn't far enough through initialization to have a target
+// selected (which is required to compute state file paths).
+func readStateForMetadata(ctx context.Context, b *bundle.Bundle) (string, int64, map[string][]int64) {
+	if b.Target == nil {
+		return "", 0, nil
+	}
+
+	if _, localPath := b.StateFilenameDirect(ctx); localPath != "" {
+		raw, err := readStateFile(localPath)
+		if err == nil && raw != nil {
+			return "direct", int64(len(raw)), parseDirectStateSizes(ctx, raw)
+		}
+		if err != nil {
+			log.Debugf(ctx, "resources-metadata telemetry: skipping direct state at %s: %s", localPath, err)
+		}
+	}
+
+	if _, localPath := b.StateFilenameTerraform(ctx); localPath != "" {
+		raw, err := readStateFile(localPath)
+		if errors.Is(err, fs.ErrNotExist) {
+			altPath := terraformCacheStatePath(ctx, b)
+			if altPath != localPath && altPath != "" {
+				raw, err = readStateFile(altPath)
+			}
+		}
+		if err == nil && raw != nil {
+			return "terraform", int64(len(raw)), parseTerraformStateSizes(ctx, raw)
+		}
+		if err != nil {
+			log.Debugf(ctx, "resources-metadata telemetry: skipping terraform state at %s: %s", localPath, err)
+		}
+	}
+
+	return "", 0, nil
+}
+
+func readStateFile(path string) ([]byte, error) {
+	if path == "" {
+		return nil, nil
+	}
+	raw, err := os.ReadFile(path)
+	if errors.Is(err, fs.ErrNotExist) {
+		return nil, nil
+	}
+	return raw, err
+}
+
+func terraformCacheStatePath(ctx context.Context, b *bundle.Bundle) string {
+	dir, err := terraform.Dir(ctx, b)
+	if err != nil {
+		return ""
+	}
+	return filepath.Join(dir, "terraform.tfstate")
+}
+
+func parseDirectStateSizes(ctx context.Context, raw []byte) map[string][]int64 {
+	var db dstate.Database
+	if err := json.Unmarshal(raw, &db); err != nil {
+		log.Debugf(ctx, "resources-metadata telemetry: failed to parse direct state: %s", err)
+		return nil
+	}
+	byType := make(map[string][]int64)
+	for key, entry := range db.State {
+		t := resourceTypeFromKey(key)
+		if t == "" {
+			continue
+		}
+		byType[t] = append(byType[t], int64(len(entry.State)))
+	}
+	return byType
+}
+
+func parseTerraformStateSizes(ctx context.Context, raw []byte) map[string][]int64 {
+	var state struct {
+		Version   int `json:"version"`
+		Resources []struct {
+			Type      string              `json:"type"`
+			Mode      tfjson.ResourceMode `json:"mode"`
+			Instances []struct {
+				Attributes json.RawMessage `json:"attributes"`
+			} `json:"instances"`
+		} `json:"resources"`
+	}
+	if err := json.Unmarshal(raw, &state); err != nil {
+		log.Debugf(ctx, "resources-metadata telemetry: failed to parse terraform state: %s", err)
+		return nil
+	}
+	byType := make(map[string][]int64)
+	for _, resource := range state.Resources {
+		if resource.Mode != tfjson.ManagedResourceMode {
+			continue
+		}
+		groupName, ok := terraform.TerraformToGroupName[resource.Type]
+		if !ok {
+			continue
+		}
+		for _, instance := range resource.Instances {
+			byType[groupName] = append(byType[groupName], int64(len(instance.Attributes)))
+		}
+	}
+	return byType
+}
+
+// resourceTypeFromKey extracts the resource type from a direct-engine state
+// key. Direct-engine keys are of the form "resources.<type>.<name>" or
+// "resources.<type>.<name>.<sub>" (for permissions/grants/secret_acls).
+// Returns "" for keys that don't match.
+func resourceTypeFromKey(key string) string {
+	parts := strings.SplitN(key, ".", 4)
+	if len(parts) < 3 || parts[0] != "resources" {
+		return ""
+	}
+	if len(parts) == 4 {
+		// Sub-resources like permissions / grants / secret_acls live at
+		// "resources.<parent>.<name>.<sub>". Track them under the sub-resource
+		// type so they aggregate across resource families.
+		return parts[3]
+	}
+	return parts[1]
+}
+
+func unionKeys(a map[string]int64, b map[string][]int64) []string {
+	seen := make(map[string]struct{}, len(a)+len(b))
+	for k := range a {
+		seen[k] = struct{}{}
+	}
+	for k := range b {
+		seen[k] = struct{}{}
+	}
+	out := make([]string, 0, len(seen))
+	for k := range seen {
+		out = append(out, k)
+	}
+	return out
+}
+
+func statMax(sortedSizes []int64) int64 {
+	if len(sortedSizes) == 0 {
+		return 0
+	}
+	return sortedSizes[len(sortedSizes)-1]
+}
+
+func statMean(sortedSizes []int64) int64 {
+	if len(sortedSizes) == 0 {
+		return 0
+	}
+	var total int64
+	for _, s := range sortedSizes {
+		total += s
+	}
+	return total / int64(len(sortedSizes))
+}
+
+func statMedian(sortedSizes []int64) int64 {
+	if len(sortedSizes) == 0 {
+		return 0
+	}
+	return sortedSizes[(len(sortedSizes)-1)/2]
+}