Make collecting Prometheus data optional through annotation

Currently we automatically collect Prometheus data for PSM
related tests, now some regular tests (same scenario as PSM
test) are also part of the PSM tests, we may want to collect
Prometheus data for those regular tests too. The current method
for checking if a rest is a PSM test to check the existence of
xds-server and sidecar containers.
It is hard to apply the same mechanism for PSM related regular
tests,  the simplest way is to add an annotation like
`enablePrometheus:true` to control if we want to use Prometheus
for a given test.

config/constants.go

@@ -66,6 +66,10 @@ const (
 	// DriverPortEnv specifies the name of the env variable that contains driver port.
 	DriverPortEnv = "DRIVER_PORT"
 
+	// EnablePrometheusEnv specifies the name of the env variable that indicates if the
+	// Prometheus data is collected.
+	EnablePrometheusEnv = "ENABLE_PROMETHEUS"
+
 	// PoolLabel is the key for a label which will have the name of a pool as
 	// the value.
 	PoolLabel = "pool"

containers/runtime/driver/run.sh

@@ -35,7 +35,7 @@ if [ -n "${BQ_RESULT_TABLE}" ]; then
   fi
   if [ -r "${NODE_INFO_OUTPUT_FILE}" ]; then
     cp "${NODE_INFO_OUTPUT_FILE}" node_info.json
-    if [ -n "${SERVER_TARGET_OVERRIDE}" ]; then
+    if [ -n "${SERVER_TARGET_OVERRIDE}" ] || [ -n "${ENABLE_PROMETHEUS}" ]; then
       python3 /src/code/tools/run_tests/performance/prometheus.py \
         --url=http://prometheus.test-infra-system.svc.cluster.local:9090 \
         --pod_type=clients --container_name=main \

kubehelpers/psm.go

@@ -20,7 +20,7 @@ import (
 	"github.com/grpc/test-infra/config"
 )
 
-//IsPSMTest checks if a given LoadTest is a (proxied or proxyless) service
+// IsPSMTest checks if a given LoadTest is a (proxied or proxyless) service
 // mesh test. This test must be performed after validating the client specs.
 func IsPSMTest(clients *[]grpcv1.Client) bool {
 	for _, c := range *clients {

podbuilder/podbuilder.go

@@ -18,6 +18,7 @@ package podbuilder
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/pkg/errors"
 	corev1 "k8s.io/api/core/v1"
@@ -240,6 +241,14 @@ func (pb *PodBuilder) PodForDriver(driver *grpcv1.Driver) (*corev1.Pod, error) {
 		}
 	}
 
+	usePrometheus, ok := pb.test.Annotations["enablePrometheus"]
+	if ok && strings.ToLower(usePrometheus) == "true" {
+		runContainer.Env = append(runContainer.Env,
+			corev1.EnvVar{
+				Name:  config.EnablePrometheusEnv,
+				Value: "true"})
+	}
+
 	return pod, nil
 }
 

status/missing_pods_test.go

@@ -5,7 +5,7 @@ Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
 
-    http://www.apache.org/licenses/LICENSE-2.0
+	http://www.apache.org/licenses/LICENSE-2.0
 
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,