Add prometheus metric support. (#92)

Author: robholland

app/server/server.go

@@ -9,14 +9,19 @@ import (
 	"os"
 	"slices"
 	"strings"
+	"time"
 
+	prom "github.com/prometheus/client_golang/prometheus"
 	"github.com/temporalio/reference-app-orders-go/app/billing"
 	"github.com/temporalio/reference-app-orders-go/app/config"
 	"github.com/temporalio/reference-app-orders-go/app/db"
 	"github.com/temporalio/reference-app-orders-go/app/fraud"
 	"github.com/temporalio/reference-app-orders-go/app/order"
 	"github.com/temporalio/reference-app-orders-go/app/shipment"
+	"github.com/uber-go/tally/v4"
+	"github.com/uber-go/tally/v4/prometheus"
 	"go.temporal.io/sdk/client"
+	sdktally "go.temporal.io/sdk/contrib/tally"
 	"go.temporal.io/sdk/log"
 	"golang.org/x/sync/errgroup"
 )
@@ -35,6 +40,7 @@ import (
 func CreateClientOptionsFromEnv() (client.Options, error) {
 	hostPort := os.Getenv("TEMPORAL_ADDRESS")
 	namespaceName := os.Getenv("TEMPORAL_NAMESPACE")
+	logger := slog.Default()
 
 	// Must explicitly set the Namepace for non-cloud use.
 	if strings.Contains(hostPort, ".tmprl.cloud:") && namespaceName == "" {
@@ -49,7 +55,7 @@ func CreateClientOptionsFromEnv() (client.Options, error) {
 	clientOpts := client.Options{
 		HostPort:  hostPort,
 		Namespace: namespaceName,
-		Logger:    log.NewStructuredLogger(slog.Default()),
+		Logger:    log.NewStructuredLogger(logger),
 	}
 
 	if certPath := os.Getenv("TEMPORAL_TLS_CERT"); certPath != "" {
@@ -63,9 +69,44 @@ func CreateClientOptionsFromEnv() (client.Options, error) {
 		}
 	}
 
+	endpoint := os.Getenv("TEMPORAL_METRICS_ENDPOINT")
+	if endpoint != "" {
+		scope, err := newPrometheusScope(prometheus.Configuration{
+			ListenAddress: endpoint,
+			TimerType:     "histogram",
+		}, logger)
+		if err != nil {
+			return clientOpts, fmt.Errorf("failed to create metrics scope: %w", err)
+		}
+		clientOpts.MetricsHandler = sdktally.NewMetricsHandler(scope)
+	}
+
 	return clientOpts, nil
 }
 
+func newPrometheusScope(c prometheus.Configuration, logger *slog.Logger) (tally.Scope, error) {
+	reporter, err := c.NewReporter(
+		prometheus.ConfigurationOptions{
+			Registry: prom.NewRegistry(),
+			OnError: func(err error) {
+				logger.Error("error in prometheus reporter", "error", err)
+			},
+		},
+	)
+	if err != nil {
+		return nil, fmt.Errorf("error creating prometheus reporter: %w", err)
+	}
+	scopeOpts := tally.ScopeOptions{
+		CachedReporter:  reporter,
+		Separator:       prometheus.DefaultSeparator,
+		SanitizeOptions: &sdktally.PrometheusSanitizeOptions,
+	}
+	scope, _ := tally.NewRootScope(scopeOpts, time.Second)
+	scope = sdktally.NewPrometheusNamingScope(scope)
+
+	return scope, nil
+}
+
 // RunWorkers runs workers for the requested services.
 func RunWorkers(ctx context.Context, config config.AppConfig, client client.Client, services []string) error {
 	ctx, cancel := context.WithCancel(ctx)
@@ -150,10 +191,6 @@ func runAPIServer(ctx context.Context, hostPort string, router http.Handler, log
 	return nil
 }
 
-func serverHostPort(config config.AppConfig, port int32) string {
-	return fmt.Sprintf("%s:%d", config.BindOnIP, port)
-}
-
 // RunAPIServers runs API servers for the requested services.
 func RunAPIServers(ctx context.Context, config config.AppConfig, client client.Client, services []string) error {
 	ctx, cancel := context.WithCancel(ctx)

go.mod

@@ -1,15 +1,20 @@
 module github.com/temporalio/reference-app-orders-go
 
 go 1.22.0
+
 require (
 	github.com/google/uuid v1.6.0
 	github.com/jmoiron/sqlx v1.4.0
+	github.com/prometheus/client_golang v1.16.0
 	github.com/spf13/cobra v1.8.1
 	github.com/stretchr/testify v1.10.0
 	github.com/testcontainers/testcontainers-go/modules/mongodb v0.33.0
+	github.com/uber-go/tally/v4 v4.1.17
 	go.mongodb.org/mongo-driver v1.17.0
 	go.temporal.io/api v1.44.1
 	go.temporal.io/sdk v1.33.0
+	go.temporal.io/sdk/contrib/opentelemetry v0.6.0
+	go.temporal.io/sdk/contrib/tally v0.2.0
 	golang.org/x/sync v0.11.0
 	modernc.org/sqlite v1.34.1
 )
@@ -18,7 +23,9 @@ require (
 	dario.cat/mergo v1.0.0 // indirect
 	github.com/Azure/go-ansiterm v0.0.0-20210617225240-d185dfc1b5a1 // indirect
 	github.com/Microsoft/go-winio v0.6.2 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cenkalti/backoff/v4 v4.2.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/containerd/containerd v1.7.27 // indirect
 	github.com/containerd/log v0.1.0 // indirect
 	github.com/containerd/platforms v0.2.1 // indirect
@@ -36,6 +43,7 @@ require (
 	github.com/go-ole/go-ole v1.2.6 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/golang/mock v1.6.0 // indirect
+	github.com/golang/protobuf v1.5.4 // indirect
 	github.com/golang/snappy v0.0.4 // indirect
 	github.com/grpc-ecosystem/go-grpc-middleware v1.4.0 // indirect
 	github.com/grpc-ecosystem/grpc-gateway/v2 v2.22.0 // indirect
@@ -45,6 +53,7 @@ require (
 	github.com/lufia/plan9stats v0.0.0-20211012122336-39d0f177ccd0 // indirect
 	github.com/magiconair/properties v1.8.7 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
 	github.com/moby/docker-image-spec v1.3.1 // indirect
 	github.com/moby/patternmatcher v0.6.0 // indirect
 	github.com/moby/sys/sequential v0.5.0 // indirect
@@ -61,6 +70,9 @@ require (
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/power-devops/perfstat v0.0.0-20210106213030-5aafc221ea8c // indirect
+	github.com/prometheus/client_model v0.3.0 // indirect
+	github.com/prometheus/common v0.42.0 // indirect
+	github.com/prometheus/procfs v0.10.1 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
 	github.com/robfig/cron v1.2.0 // indirect
 	github.com/shirou/gopsutil/v3 v3.23.12 // indirect
@@ -71,15 +83,17 @@ require (
 	github.com/testcontainers/testcontainers-go v0.33.0 // indirect
 	github.com/tklauser/go-sysconf v0.3.12 // indirect
 	github.com/tklauser/numcpus v0.6.1 // indirect
+	github.com/twmb/murmur3 v1.1.8 // indirect
 	github.com/xdg-go/pbkdf2 v1.0.0 // indirect
 	github.com/xdg-go/scram v1.1.2 // indirect
 	github.com/xdg-go/stringprep v1.0.4 // indirect
 	github.com/youmark/pkcs8 v0.0.0-20240726163527-a2c0da244d78 // indirect
 	github.com/yusufpapurcu/wmi v1.2.3 // indirect
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.49.0 // indirect
-	go.opentelemetry.io/otel v1.24.0 // indirect
-	go.opentelemetry.io/otel/metric v1.24.0 // indirect
-	go.opentelemetry.io/otel/trace v1.24.0 // indirect
+	go.opentelemetry.io/otel v1.27.0 // indirect
+	go.opentelemetry.io/otel/metric v1.27.0 // indirect
+	go.opentelemetry.io/otel/trace v1.27.0 // indirect
+	go.uber.org/atomic v1.11.0 // indirect
 	golang.org/x/crypto v0.31.0 // indirect
 	golang.org/x/net v0.33.0 // indirect
 	golang.org/x/sys v0.28.0 // indirect