From e77921a4b2b034c3aa87a301a5559bad29e6b46d Mon Sep 17 00:00:00 2001
From: "Masih H. Derkani" <m@derkani.org>
Date: Tue, 23 Jul 2024 22:49:40 +0100
Subject: [PATCH] Set up otel metrics reporting to prometheus

Register otel collector bridging to the default prometheus registry so
that F3 metrics (which use the newer otel APIs for metrics) get included
in Lotus metrics.
---
 chain/lf3/f3.go | 17 +++++++++++++++++
 go.mod          |  3 ++-
 go.sum          |  2 ++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/chain/lf3/f3.go b/chain/lf3/f3.go
index 59fa803fa39..fb080eb018c 100644
--- a/chain/lf3/f3.go
+++ b/chain/lf3/f3.go
@@ -10,6 +10,9 @@ import (
 	logging "github.com/ipfs/go-log/v2"
 	pubsub "github.com/libp2p/go-libp2p-pubsub"
 	"github.com/libp2p/go-libp2p/core/host"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/prometheus"
+	"go.opentelemetry.io/otel/sdk/metric"
 	"go.uber.org/fx"
 	"golang.org/x/xerrors"
 
@@ -50,6 +53,20 @@ type F3Params struct {
 
 var log = logging.Logger("f3")
 
+func init() {
+	// Set up otel to prometheus reporting so that F3 metrics are reported via lotus
+	// prometheus metrics. This bridge eventually gets picked up by opencensus
+	// exporter as HTTP handler. This by default registers an otel collector against
+	// the global prometheus registry. In the future, we should clean up metrics in
+	// Lotus and move it all to use otel. For now, bridge away.
+	if bridge, err := prometheus.New(); err != nil {
+		log.Errorf("could not create the otel prometheus exporter: %v", err)
+	} else {
+		provider := metric.NewMeterProvider(metric.WithReader(bridge))
+		otel.SetMeterProvider(provider)
+	}
+}
+
 func New(mctx helpers.MetricsCtx, lc fx.Lifecycle, params F3Params) (*F3, error) {
 
 	ds := namespace.Wrap(params.Datastore, datastore.NewKey("/f3"))
diff --git a/go.mod b/go.mod
index 12f003c45ad..96ba030340d 100644
--- a/go.mod
+++ b/go.mod
@@ -144,7 +144,9 @@ require (
 	go.opentelemetry.io/otel v1.28.0
 	go.opentelemetry.io/otel/bridge/opencensus v1.28.0
 	go.opentelemetry.io/otel/exporters/jaeger v1.14.0
+	go.opentelemetry.io/otel/exporters/prometheus v0.50.0
 	go.opentelemetry.io/otel/sdk v1.28.0
+	go.opentelemetry.io/otel/sdk/metric v1.28.0
 	go.uber.org/atomic v1.11.0
 	go.uber.org/fx v1.22.1
 	go.uber.org/multierr v1.11.0
@@ -316,7 +318,6 @@ require (
 	github.com/zondax/hid v0.9.2 // indirect
 	github.com/zondax/ledger-go v0.14.3 // indirect
 	go.opentelemetry.io/otel/metric v1.28.0 // indirect
-	go.opentelemetry.io/otel/sdk/metric v1.28.0 // indirect
 	go.opentelemetry.io/otel/trace v1.28.0 // indirect
 	go.uber.org/dig v1.17.1 // indirect
 	go.uber.org/mock v0.4.0 // indirect
diff --git a/go.sum b/go.sum
index e3fa43b5ed7..86c1a7ab933 100644
--- a/go.sum
+++ b/go.sum
@@ -1387,6 +1387,8 @@ go.opentelemetry.io/otel/bridge/opencensus v1.28.0 h1:/BcyAV1bUJjSVxoeKwTQL9cS4X
 go.opentelemetry.io/otel/bridge/opencensus v1.28.0/go.mod h1:FZp2xE+46yAyp3DfLFALze58nY0iIE8zs+mCgkPAzq0=
 go.opentelemetry.io/otel/exporters/jaeger v1.14.0 h1:CjbUNd4iN2hHmWekmOqZ+zSCU+dzZppG8XsV+A3oc8Q=
 go.opentelemetry.io/otel/exporters/jaeger v1.14.0/go.mod h1:4Ay9kk5vELRrbg5z4cpP9EtmQRFap2Wb0woPG4lujZA=
+go.opentelemetry.io/otel/exporters/prometheus v0.50.0 h1:2Ewsda6hejmbhGFyUvWZjUThC98Cf8Zy6g0zkIimOng=
+go.opentelemetry.io/otel/exporters/prometheus v0.50.0/go.mod h1:pMm5PkUo5YwbLiuEf7t2xg4wbP0/eSJrMxIMxKosynY=
 go.opentelemetry.io/otel/metric v1.28.0 h1:f0HGvSl1KRAU1DLgLGFjrwVyismPlnuU6JD6bOeuA5Q=
 go.opentelemetry.io/otel/metric v1.28.0/go.mod h1:Fb1eVBFZmLVTMb6PPohq3TO9IIhUisDsbJoL/+uQW4s=
 go.opentelemetry.io/otel/sdk v1.28.0 h1:b9d7hIry8yZsgtbmM0DKyPWMMUMlK9NEKuIG4aBqWyE=