feat(reexecute/c): explicit metrics port

Taskfile.yml

@@ -205,6 +205,7 @@ tasks:
       BENCHMARK_OUTPUT_FILE: '{{.BENCHMARK_OUTPUT_FILE | default ""}}'
       METRICS_SERVER_ENABLED: '{{.METRICS_SERVER_ENABLED | default "false"}}'
       METRICS_COLLECTOR_ENABLED: '{{.METRICS_COLLECTOR_ENABLED | default "false"}}'
+      METRICS_SERVER_PORT: '{{.METRICS_SERVER_PORT}}'
     cmd: |
       CURRENT_STATE_DIR={{.CURRENT_STATE_DIR}} \
       BLOCK_DIR={{.BLOCK_DIR}} \
@@ -216,6 +217,7 @@ tasks:
       BENCHMARK_OUTPUT_FILE={{.BENCHMARK_OUTPUT_FILE}} \
       METRICS_SERVER_ENABLED={{.METRICS_SERVER_ENABLED}} \
       METRICS_COLLECTOR_ENABLED={{.METRICS_COLLECTOR_ENABLED}} \
+      METRICS_SERVER_PORT={{.METRICS_SERVER_PORT}} \
       bash -x ./scripts/benchmark_cchain_range.sh
 
   reexecute-cchain-range-with-copied-data:
@@ -232,6 +234,7 @@ tasks:
       BENCHMARK_OUTPUT_FILE: '{{.BENCHMARK_OUTPUT_FILE | default ""}}'
       METRICS_SERVER_ENABLED: '{{.METRICS_SERVER_ENABLED | default "false"}}'
       METRICS_COLLECTOR_ENABLED: '{{.METRICS_COLLECTOR_ENABLED | default "false"}}'
+      METRICS_SERVER_PORT: '{{.METRICS_SERVER_PORT}}'
     cmds:
       - task: import-cchain-reexecute-range
         vars:
@@ -250,6 +253,7 @@ tasks:
           BENCHMARK_OUTPUT_FILE: '{{.BENCHMARK_OUTPUT_FILE}}'
           METRICS_SERVER_ENABLED: '{{.METRICS_SERVER_ENABLED}}'
           METRICS_COLLECTOR_ENABLED: '{{.METRICS_COLLECTOR_ENABLED}}'
+          METRICS_SERVER_PORT: '{{.METRICS_SERVER_PORT}}'
 
   test-bootstrap-monitor-e2e:
     desc: Runs bootstrap monitor e2e tests

scripts/benchmark_cchain_range.sh

@@ -12,6 +12,7 @@ set -euo pipefail
 #   BENCHMARK_OUTPUT_FILE (optional): If set, benchmark output is also written to this file.
 #   METRICS_SERVER_ENABLED (optional): If set, enables the metrics server.
 #   METRICS_COLLECTOR_ENABLED (optional): If set, enables the metrics collector.
+#   METRICS_SERVER_PORT (optional): If set, determines the port the metrics server will listen to.
 
 : "${BLOCK_DIR:?BLOCK_DIR must be set}"
 : "${CURRENT_STATE_DIR:?CURRENT_STATE_DIR must be set}"
@@ -28,7 +29,8 @@ cmd="go test -timeout=0 -v -benchtime=1x -bench=BenchmarkReexecuteRange -run=^$
   --end-block=\"${END_BLOCK}\" \
   ${LABELS:+--labels=\"${LABELS}\"} \
   ${METRICS_SERVER_ENABLED:+--metrics-server-enabled=\"${METRICS_SERVER_ENABLED}\"} \
-  ${METRICS_COLLECTOR_ENABLED:+--metrics-collector-enabled=\"${METRICS_COLLECTOR_ENABLED}\"}"
+  ${METRICS_COLLECTOR_ENABLED:+--metrics-collector-enabled=\"${METRICS_COLLECTOR_ENABLED}\"} \
+  ${METRICS_SERVER_PORT:+--metrics-server-port=\"${METRICS_SERVER_PORT}\"}"
 
 if [ -n "${BENCHMARK_OUTPUT_FILE:-}" ]; then
   eval "$cmd" | tee "${BENCHMARK_OUTPUT_FILE}"

tests/prometheus_server.go

@@ -6,6 +6,7 @@ package tests
 import (
 	"context"
 	"errors"
+	"fmt"
 	"net"
 	"net/http"
 	"time"
@@ -14,7 +15,10 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
-const defaultPrometheusListenAddr = "127.0.0.1:0"
+const (
+	localhostAddr      = "127.0.0.1"
+	defaultMetricsPort = 0
+)
 
 // PrometheusServer is a HTTP server that serves Prometheus metrics from the provided
 // gahterer.
@@ -28,25 +32,32 @@ type PrometheusServer struct {
 // NewPrometheusServer creates and starts a Prometheus server with the provided gatherer
 // listening on 127.0.0.1:0 and serving /ext/metrics.
 func NewPrometheusServer(gatherer prometheus.Gatherer) (*PrometheusServer, error) {
+	return NewPrometheusServerWithPort(gatherer, defaultMetricsPort)
+}
+
+// NewPrometheusServer creates and starts a Prometheus server with the provided gatherer
+// listening on 127.0.0.1:port and serving /ext/metrics.
+func NewPrometheusServerWithPort(gatherer prometheus.Gatherer, port uint64) (*PrometheusServer, error) {
 	server := &PrometheusServer{
 		gatherer: gatherer,
 	}
 
-	if err := server.start(); err != nil {
+	serverAddress := fmt.Sprintf("%s:%d", localhostAddr, port)
+	if err := server.start(serverAddress); err != nil {
 		return nil, err
 	}
 
 	return server, nil
 }
 
-// start the Prometheus server on a dynamic port.
-func (s *PrometheusServer) start() error {
+// start the Prometheus server on address.
+func (s *PrometheusServer) start(address string) error {
 	mux := http.NewServeMux()
 	mux.Handle("/ext/metrics", promhttp.HandlerFor(s.gatherer, promhttp.HandlerOpts{}))
 
-	listener, err := net.Listen("tcp", defaultPrometheusListenAddr)
+	listener, err := net.Listen("tcp", address)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to listen on %s: %w", address, err)
 	}
 
 	s.server = http.Server{

tests/reexecute/c/README.md

@@ -46,6 +46,7 @@ If running locally, metrics collection can be customized via the following param
 
 - `METRICS_SERVER_ENABLED`: starts a Prometheus server exporting VM metrics.
 - `METRICS_COLLECTOR_ENABLED`: starts a Prometheus collector (if enabled, then `METRICS_SERVER_ENABLED` must be enabled as well).
+- `METRICS_SERVER_PORT`: determines the port the metrics server will listen to (set to `0` by default)
 
 When utilizing the metrics collector feature, follow the instructions in the e2e [README](../../e2e/README.md#monitoring) to set the required Prometheus environment variables.
 

tests/reexecute/c/vm_reexecute_test.go

@@ -65,6 +65,7 @@ var (
 
 	metricsServerEnabledArg    bool
 	metricsCollectorEnabledArg bool
+	metricsServerPort          uint64
 
 	networkUUID string = uuid.NewString()
 	labels             = map[string]string{
@@ -106,6 +107,7 @@ func TestMain(m *testing.M) {
 
 	flag.BoolVar(&metricsServerEnabledArg, "metrics-server-enabled", false, "Whether to enable the metrics server.")
 	flag.BoolVar(&metricsCollectorEnabledArg, "metrics-collector-enabled", false, "Whether to enable the metrics collector (if true, then metrics-server-enabled must be true as well).")
+	flag.Uint64Var(&metricsServerPort, "metrics-server-port", metricsServerPort, "Port which the metrics server will listen to")
 	flag.StringVar(&labelsArg, "labels", "", "Comma separated KV list of metric labels to attach to all exported metrics. Ex. \"owner=tim,runner=snoopy\"")
 
 	predefinedConfigKeys := slices.Collect(maps.Keys(predefinedConfigs))
@@ -159,6 +161,7 @@ func BenchmarkReexecuteRange(b *testing.B) {
 			chanSizeArg,
 			metricsServerEnabledArg,
 			metricsCollectorEnabledArg,
+			metricsServerPort,
 		)
 	})
 }
@@ -173,6 +176,7 @@ func benchmarkReexecuteRange(
 	chanSize int,
 	metricsServerEnabled bool,
 	metricsCollectorEnabled bool,
+	metricsPort uint64,
 ) {
 	r := require.New(b)
 	ctx := context.Background()
@@ -192,7 +196,7 @@ func benchmarkReexecuteRange(
 	log := tests.NewDefaultLogger("c-chain-reexecution")
 
 	if metricsServerEnabled {
-		serverAddr := startServer(b, log, prefixGatherer)
+		serverAddr := startServer(b, log, prefixGatherer, metricsPort)
 
 		if metricsCollectorEnabled {
 			startCollector(b, log, "c-chain-reexecution", labels, serverAddr)
@@ -565,10 +569,11 @@ func startServer(
 	tb testing.TB,
 	log logging.Logger,
 	gatherer prometheus.Gatherer,
+	port uint64,
 ) string {
 	r := require.New(tb)
 
-	server, err := tests.NewPrometheusServer(gatherer)
+	server, err := tests.NewPrometheusServerWithPort(gatherer, port)
 	r.NoError(err)
 
 	log.Info("metrics endpoint available",