cmd/internal/cmdconfig: include Cloud Run instance ID in logs

This aids in diagnosing per-instance issues. The instance ID seems like
it would belong in the MonitoredResource labels (configured in
serverconfig), but the top-level instanceId field is the standard name
for this field on Cloud Run.

Log messages going directly to stderr (before we configure logging) get
this label automatically from the Cloud Run infra. When we use
stackdriver directly we apparently need to add this ourselves.

See https://cloud.google.com/run/docs/logging#service-fields.

Change-Id: I6a6a636cb11a2abc00347e0679605ebbdb9995f4
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/700396
Reviewed-by: Jonathan Amsterdam <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
kokoro-CI: kokoro <[email protected]>

Author: prattmic

cmd/internal/cmdconfig/cmdconfig.go

@@ -36,6 +36,13 @@ func Logger(ctx context.Context, cfg *config.Config, logName string) middleware.
 			Type:   cfg.MonitoredResource.Type,
 			Labels: cfg.MonitoredResource.Labels,
 		})}
+		if serverconfig.OnCloudRun() {
+			opts = append(opts, logging.CommonLabels(map[string]string{
+				// Standard label for Cloud Run instance ID.
+				// See https://cloud.google.com/run/docs/logging#service-fields.
+				"instanceId": cfg.InstanceID,
+			}))
+		}
 		if serverconfig.OnGKE() {
 			opts = append(opts, logging.CommonLabels(map[string]string{
 				"k8s-pod/env": cfg.DeploymentEnvironment(),

internal/config/serverconfig/config.go

@@ -85,8 +85,8 @@ func OnGKE() bool {
 	return os.Getenv("GO_DISCOVERY_ON_GKE") == "true"
 }
 
-// onCloudRun reports whether the current process is running on Cloud Run.
-func onCloudRun() bool {
+// OnCloudRun reports whether the current process is running on Cloud Run.
+func OnCloudRun() bool {
 	// Use the presence of the environment variables provided by Cloud Run.
 	// See https://cloud.google.com/run/docs/reference/container-contract.
 	for _, ev := range []string{"K_SERVICE", "K_REVISION", "K_CONFIGURATION"} {
@@ -100,7 +100,7 @@ func onCloudRun() bool {
 // OnGCP reports whether the current process is running on Google Cloud
 // Platform.
 func OnGCP() bool {
-	return OnAppEngine() || OnGKE() || onCloudRun()
+	return OnAppEngine() || OnGKE() || OnCloudRun()
 }
 
 // configOverride holds selected config settings that can be dynamically overridden.
@@ -212,7 +212,7 @@ func Init(ctx context.Context) (_ *config.Config, err error) {
 					"zone":       cfg.ZoneID,
 				},
 			}
-		case onCloudRun():
+		case OnCloudRun():
 			cfg.MonitoredResource = &config.MonitoredResource{
 				Type: "cloud_run_revision",
 				Labels: map[string]string{