zero/telemetry: add reporter (#4855)

internal/zero/reporter/reporter.go

@@ -0,0 +1,61 @@
+// Package reporter periodically submits metrics back to the cloud.
+package reporter
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	export_grpc "go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
+	metric_sdk "go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/resource"
+	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
+	"google.golang.org/grpc"
+
+	"github.com/pomerium/pomerium/internal/log"
+	"github.com/pomerium/pomerium/internal/version"
+)
+
+// Run starts loop that pushes metrics via OTEL protocol until ctx is canceled
+func Run(
+	ctx context.Context,
+	conn *grpc.ClientConn,
+	opts ...Option,
+) error {
+	cfg := getConfig(opts...)
+
+	exporter, err := export_grpc.New(ctx, export_grpc.WithGRPCConn(conn))
+	if err != nil {
+		return fmt.Errorf("starting OTEL exporter: %w", err)
+	}
+	defer shutdown(exporter.Shutdown, cfg.shutdownTimeout)
+
+	provider := metric_sdk.NewMeterProvider(
+		metric_sdk.WithResource(resource.NewSchemaless(
+			semconv.ServiceNameKey.String("pomerium-managed-core"),
+			semconv.ServiceVersionKey.String(version.FullVersion()),
+		)),
+		metric_sdk.WithReader(
+			metric_sdk.NewPeriodicReader(
+				exporter,
+				metric_sdk.WithInterval(cfg.collectInterval),
+			)))
+	defer shutdown(provider.Shutdown, cfg.shutdownTimeout)
+
+	meter := provider.Meter("pomerium-managed-core")
+	for _, fn := range cfg.metrics {
+		err := fn(meter)
+		if err != nil {
+			log.Ctx(ctx).Error().Err(err).Msg("error registering metric")
+		}
+	}
+
+	<-ctx.Done()
+	return ctx.Err()
+}
+
+func shutdown(fn func(ctx context.Context) error, timeout time.Duration) {
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+	_ = fn(ctx)
+}