Expose metrics for libp2p using OpenTelemetry (#2074)

libp2p _used_ to support metrics using OpenCensus, but this was recently
changed to use Prometheus instead -
libp2p/go-libp2p#1955. Unfortunately, it is
extremely difficult to get Prometheus metrics into OpenTelemetry without
running the external OTEL agent.

This re-implements the same metrics using OpenTelemetry using the _new_
Prometheus names rather than the old OpenCensus naming.

Fixes #2059

go.mod

@@ -74,7 +74,6 @@ require (
 	github.com/xeipuuv/gojsonschema v1.2.0
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.39.0
 	go.opentelemetry.io/otel v1.13.0
-	go.opentelemetry.io/otel/bridge/opencensus v0.36.0
 	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v0.35.0
 	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v0.35.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.13.0

go.sum

@@ -2331,8 +2331,6 @@ go.opentelemetry.io/otel v1.3.0/go.mod h1:PWIKzi6JCp7sM0k9yZ43VX+T345uNbAkDKwHVj
 go.opentelemetry.io/otel v1.7.0/go.mod h1:5BdUoMIz5WEs0vt0CUEMtSSaTSHBBVwrhnz7+nrD5xk=
 go.opentelemetry.io/otel v1.13.0 h1:1ZAKnNQKwBBxFtww/GwxNUyTf0AxkZzrukO8MeXqe4Y=
 go.opentelemetry.io/otel v1.13.0/go.mod h1:FH3RtdZCzRkJYFTCsAKDy9l/XYjMdNv6QrkFFB8DvVg=
-go.opentelemetry.io/otel/bridge/opencensus v0.36.0 h1:/RJRbdVBP+Yoh6tx8zu0L+b1KE/iGmo3adr5LUvCGWA=
-go.opentelemetry.io/otel/bridge/opencensus v0.36.0/go.mod h1:otgxgSPzGNRPjDYJUrQwqGu4MXRngDPEbFxuVl355Fk=
 go.opentelemetry.io/otel/exporters/jaeger v1.7.0 h1:wXgjiRldljksZkZrldGVe6XrG9u3kYDyQmkZwmm5dI0=
 go.opentelemetry.io/otel/exporters/jaeger v1.7.0/go.mod h1:PwQAOqBgqbLQRKlj466DuD2qyMjbtcPpfPfj+AqbSBs=
 go.opentelemetry.io/otel/exporters/otlp v0.20.0/go.mod h1:YIieizyaN77rtLJra0buKiNBOm9XQfkPEKBeuhoMwAM=

pkg/libp2p/rcmgr/defaults.go

@@ -4,10 +4,11 @@ import (
 	"github.com/bacalhau-project/bacalhau/pkg/transport/bprotocol"
 	"github.com/libp2p/go-libp2p"
 	libp2p_rcmgr "github.com/libp2p/go-libp2p/p2p/host/resource-manager"
-	"github.com/libp2p/go-libp2p/p2p/host/resource-manager/obs"
+	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/global"
 )
 
-func SetDefaultServiceLimits(config *libp2p_rcmgr.ScalingLimitConfig) {
+func setDefaultServiceLimits(config *libp2p_rcmgr.ScalingLimitConfig) {
 	// Requester -> Compute nodes
 	// reasoning behind these limits:
 	// - Requester nodes should have a high number of outbound streams to compute nodes
@@ -41,33 +42,30 @@ func SetDefaultServiceLimits(config *libp2p_rcmgr.ScalingLimitConfig) {
 	)
 }
 
-var DefaultResourceManager = func(cfg *libp2p.Config) error {
-	// Default memory limit: 1/8th of total memory, minimum 128MB, maximum 1GB
-	limits := libp2p_rcmgr.DefaultLimits
-	libp2p.SetDefaultServiceLimits(&limits)
-	SetDefaultServiceLimits(&limits)
+func DefaultResourceManager(cfg *libp2p.Config) error {
+	return resourceManagerWithMetricsProvider(global.MeterProvider())(cfg)
+}
 
-	// TODO: libp2p removed open census and replaced with prometheus metrics. But we only use
-	// opentelemetry. Somebody needs to figure out how to map or convert the prom metrics to
-	// oltp metrics.
-	// // Hook up the trace reporter metrics. This will expose all opencensus
-	// // stats via the default prometheus registry. See https://opencensus.io/exporters/supported-exporters/go/prometheus/ for other options.
-	// err := view.Register(obs.DefaultViews...)
-	// if err != nil {
-	// 	log.Warn().Err(err).Msg("failed to register resource manager metrics")
-	// }
+func resourceManagerWithMetricsProvider(provider metric.MeterProvider) func(cfg *libp2p.Config) error {
+	return func(cfg *libp2p.Config) error {
+		// Default memory limit: 1/8th of total memory, minimum 128MB, maximum 1GB
+		limits := libp2p_rcmgr.DefaultLimits
+		libp2p.SetDefaultServiceLimits(&limits)
+		setDefaultServiceLimits(&limits)
 
-	str, err := obs.NewStatsTraceReporter()
-	if err != nil {
-		return err
-	}
-	mgr, err := libp2p_rcmgr.NewResourceManager(
-		libp2p_rcmgr.NewFixedLimiter(limits.AutoScale()),
-		libp2p_rcmgr.WithTraceReporter(str),
-	)
-	if err != nil {
-		return err
-	}
+		metricReporter, err := metricsReporter(provider)
+		if err != nil {
+			return err
+		}
+
+		mgr, err := libp2p_rcmgr.NewResourceManager(
+			libp2p_rcmgr.NewFixedLimiter(limits.AutoScale()),
+			libp2p_rcmgr.WithTraceReporter(metricReporter),
+		)
+		if err != nil {
+			return err
+		}
 
-	return cfg.Apply(libp2p.ResourceManager(mgr))
+		return cfg.Apply(libp2p.ResourceManager(mgr))
+	}
 }