metric: embed source file in Metadata for CODEOWNERS resolution

Previously, metric ownership was determined by a separate
gen-metric-owners tool that scanned Go source files via AST to find
metric.Metadata definitions, mapped each to its owning team via
CODEOWNERS, and produced a metric_owners.yaml file. This file was
checked into the tree but had no Bazel genrule, and required a
bespoke step in both ./dev generate and check-generated-code CI.

This commit eliminates that pipeline by embedding source file
information directly in metric.Metadata at definition time. A new
source_file proto field is populated by metric.InitMetadata(), which
captures the caller's file via runtime.Caller. At generation time,
cockroach gen metric-list resolves ownership by calling
codeowners.Match on each metric's source file — no separate AST
scanning needed.

To enforce adoption, a new metadatanew nogo analyzer flags bare
metric.Metadata{} composite literals that aren't wrapped in
InitMetadata(). The metric registry also logs a warning when metrics
are registered without a source file set.

Removed:
- pkg/cmd/gen-metric-owners and its Bazel target
- pkg/internal/metricscan/metric_owners.yaml and its go:embed wrapper
- The generateMetricOwners step from ./dev generate
- The bazel run //pkg/cmd/gen-metric-owners step from check-generated-code.sh
- The --metric-owners flag from cockroach gen metric-list

Epic: none

Release note: None
Co-Authored-By: roachdev-claude <roachdev-claude-bot@cockroachlabs.com>

Author: angles-n-daemons

BUILD.bazel

@@ -205,6 +205,7 @@ nogo(
         "//pkg/testutils/lint/passes/grpcstatuswithdetails",
         "//pkg/testutils/lint/passes/hash",
         "//pkg/testutils/lint/passes/leaktestcall",
+        "//pkg/testutils/lint/passes/metadatanew",
         "//pkg/testutils/lint/passes/nilness",
         "//pkg/testutils/lint/passes/nocopy",
         "//pkg/testutils/lint/passes/redactcheck",

build/bazelutil/nogo_config.json

@@ -1654,5 +1654,16 @@
             "external/": "exclude all third-party code for all analyzers",
             "pkg/sql/colexec/colexechash/hash\\.go$": "re-implements runtime.noescape for efficient hashing"
         }
+    },
+    "metadatanew": {
+        "exclude_files": {
+            "external/": "exclude all third-party code",
+            ".*\\.pb\\.go$": "generated code",
+            ".*\\.pb\\.gw\\.go$": "generated code",
+            "pkg/.*\\.eg\\.go$": "generated code",
+            "pkg/.*_generated\\.go$": "generated code",
+            "pkg/util/metric/.*\\.go$": "metric package internal usage is allowed",
+            "pkg/testutils/": "test utilities may construct Metadata for testing"
+        }
     }
 }

build/github/check-generated-code.sh

@@ -61,10 +61,6 @@ if grep TODO DEPS.bzl; then
 fi
 check_workspace_clean "Run \`./dev generate bazel\` to fix this error."
 
-# Run gen-metric-owners to ensure metric_owners.yaml is up to date
-# before //pkg/gen regenerates metrics.yaml from it.
-bazel run //pkg/cmd/gen-metric-owners $ENGFLOW_ARGS -- -out="$(pwd)/pkg/internal/metricscan/metric_owners.yaml"
-
 # Run `bazel run //pkg/gen` and ensure nothing changes. This ensures
 # generated documentation and checked-in go code are up to date.
 bazel run //pkg/gen $ENGFLOW_ARGS

docs/generated/metrics/BUILD.bazel

@@ -1,10 +1,7 @@
 genrule(
     name = "metrics",
-    srcs = [
-        "//pkg/internal/metricscan:metric_owners.yaml",
-    ],
     outs = ["metrics.yaml"],
-    cmd = "$(location //pkg/cmd/cockroach-short) gen metric-list --logtostderr=NONE --metric-owners=$(location //pkg/internal/metricscan:metric_owners.yaml) > $@",
+    cmd = "$(location //pkg/cmd/cockroach-short) gen metric-list --logtostderr=NONE > $@",
     tools = ["//pkg/cmd/cockroach-short"],
     visibility = [
         ":__pkg__",

pkg/BUILD.bazel

@@ -1208,8 +1208,6 @@ GO_TARGETS = [
     "//pkg/cmd/flaky-test-notifier:flaky-test-notifier_lib",
     "//pkg/cmd/fuzz:fuzz",
     "//pkg/cmd/fuzz:fuzz_lib",
-    "//pkg/cmd/gen-metric-owners:gen-metric-owners",
-    "//pkg/cmd/gen-metric-owners:gen-metric-owners_lib",
     "//pkg/cmd/generate-acceptance-tests:generate-acceptance-tests",
     "//pkg/cmd/generate-acceptance-tests:generate-acceptance-tests_lib",
     "//pkg/cmd/generate-ash-inventory:generate-ash-inventory",
@@ -2761,6 +2759,7 @@ GO_TARGETS = [
     "//pkg/testutils/lint/passes/hash:hash_test",
     "//pkg/testutils/lint/passes/leaktestcall:leaktestcall",
     "//pkg/testutils/lint/passes/leaktestcall:leaktestcall_test",
+    "//pkg/testutils/lint/passes/metadatanew:metadatanew",
     "//pkg/testutils/lint/passes/nilness:nilness",
     "//pkg/testutils/lint/passes/nilness:nilness_test",
     "//pkg/testutils/lint/passes/nocopy:nocopy",

pkg/backup/backup_metrics.go

@@ -22,12 +22,12 @@ func (b BackupMetrics) MetricStruct() {}
 // MakeBackupMetrics instantiates the metrics for backup.
 func MakeBackupMetrics(time.Duration) metric.Struct {
 	m := &BackupMetrics{
-		LastKMSInaccessibleErrorTime: metric.NewGauge(metric.Metadata{
+		LastKMSInaccessibleErrorTime: metric.NewGauge(metric.InitMetadata(metric.Metadata{
 			Name:        "backup.last-failed-time.kms-inaccessible",
 			Help:        "The unix timestamp of the most recent failure of backup due to errKMSInaccessible by a backup specified as maintaining this metric",
 			Measurement: "Jobs",
 			Unit:        metric.Unit_TIMESTAMP_SEC,
-		}),
+		})),
 	}
 	return m
 }

pkg/backup/backup_processor_planning.go

@@ -210,7 +210,7 @@ func distBackup(
 
 	recv := sql.MakeDistSQLReceiver(
 		ctx,
-		sql.NewMetadataCallbackWriter(rowResultWriter, metaFn),
+		sql.InitMetadataCallbackWriter(rowResultWriter, metaFn),
 		tree.Rows,
 		nil,   /* rangeCache */
 		noTxn, /* txn - the flow does not read or write the database */

pkg/backup/compaction_dist.go

@@ -178,7 +178,7 @@ func runCompactionPlan(
 	rowResultWriter := sql.NewRowResultWriter(nil)
 	recv := sql.MakeDistSQLReceiver(
 		ctx,
-		sql.NewMetadataCallbackWriter(rowResultWriter, metaFn),
+		sql.InitMetadataCallbackWriter(rowResultWriter, metaFn),
 		tree.Rows,
 		nil, /* rangeCache */
 		nil, /* txn */

pkg/backup/restore_processor_planning.go

@@ -262,7 +262,7 @@ func distRestore(
 
 		recv := sql.MakeDistSQLReceiver(
 			ctx,
-			sql.NewMetadataCallbackWriter(rowResultWriter, metaFn),
+			sql.InitMetadataCallbackWriter(rowResultWriter, metaFn),
 			tree.Rows,
 			nil,   /* rangeCache */
 			noTxn, /* txn - the flow does not read or write the database */

pkg/backup/schedule_exec.go

@@ -606,7 +606,7 @@ func init() {
 				metrics: backupMetrics{
 					ExecutorMetrics:    &m,
 					ExecutorPTSMetrics: &pm,
-					RpoMetric: metric.NewGauge(metric.Metadata{
+					RpoMetric: metric.NewGauge(metric.InitMetadata(metric.Metadata{
 						Name: "schedules.BACKUP.last-completed-time",
 						Help: crstrings.UnwrapText(`
 							The unix timestamp of the most recently completed backup by a
@@ -629,16 +629,16 @@ func init() {
 							For example with a backup frequency of 60 minutes, monitor
 							time() - max_across_nodes(max_over_time(schedules_BACKUP_last_completed_time, 60min)).
 						`),
-					}),
-					RpoTenantMetric: metric.NewExportedGaugeVec(metric.Metadata{
+					})),
+					RpoTenantMetric: metric.NewExportedGaugeVec(metric.InitMetadata(metric.Metadata{
 						Name: "schedules.BACKUP.last-completed-time-by-virtual_cluster",
 						Help: crstrings.UnwrapText(`
 							The unix timestamp of the most recently completed host scheduled
 							backup by virtual cluster specified as maintaining this metric
 						`),
 						Measurement: "Jobs",
 						Unit:        metric.Unit_TIMESTAMP_SEC,
-					}, []string{"tenant_id"}),
+					}), []string{"tenant_id"}),
 				},
 			}, nil
 		})