func NewServerMetricsTrailerPropagatorInterceptor(logger log.Logger) grpc.UnaryServerInterceptor {
	return func(
		ctx context.Context,
		req interface{},
		info *grpc.UnaryServerInfo,
		handler grpc.UnaryHandler,
	) (interface{}, error) {
		resp, err := handler(ctx, req)
		select {
		case <-ctx.Done():
			return resp, err
		default:
		}
		metricsCtx := getMetricsContext(ctx)
		if metricsCtx == nil {
			return resp, err
		}
		metricsBaggage := &metricspb.Baggage{CountersInt: make(map[string]int64)}
		metricsCtx.Lock()
		for k, v := range metricsCtx.CountersInt {
			metricsBaggage.CountersInt[k] = v
		}
		metricsCtx.Unlock()
		bytes, marshalErr := metricsBaggage.Marshal()
		if marshalErr != nil {
			logger.Error("unable to marshal metric baggage", tag.Error(marshalErr))
		}
		md := metadata.Pairs(metricsTrailerKey, string(bytes))
		marshalErr = grpc.SetTrailer(ctx, md)
		if marshalErr != nil {
			logger.Error("unable to add metrics baggage to gRPC trailer", tag.Error(marshalErr))
		}
		return resp, err
	}
}
NewServerMetricsTrailerPropagatorInterceptor returns grpc server interceptor that injects metrics from context into
gRPC trailer.
package metrics
import (
	"context"
	"sync"
	metricspb "go.temporal.io/server/api/metrics/v1"
	"go.temporal.io/server/common/log"
	"go.temporal.io/server/common/log/tag"
	"google.golang.org/grpc"
	"google.golang.org/grpc/metadata"
)
type (
	metricsContextKey struct{}
	metricsContext struct {
		sync.Mutex
		CountersInt map[string]int64
	}
)
var (
	metricsTrailerKey = "metrics-trailer-bin"
	metricsCtxKey     = metricsContextKey{}
)
func NewServerMetricsContextInjectorInterceptor() grpc.UnaryServerInterceptor {
	return func(
		ctx context.Context,
		req interface{},
		info *grpc.UnaryServerInfo,
		handler grpc.UnaryHandler,
	) (interface{}, error) {
		ctxWithMetricsBaggage := AddMetricsContext(ctx)
		return handler(ctxWithMetricsBaggage, req)
	}
}
func NewClientMetricsTrailerPropagatorInterceptor(logger log.Logger) grpc.UnaryClientInterceptor {
	return func(
		ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker,
		opts ...grpc.CallOption,
	) error {
		var trailer metadata.MD
		optsWithTrailer := append(opts, grpc.Trailer(&trailer))
		err := invoker(ctx, method, req, reply, cc, optsWithTrailer...)
		baggageStrings := trailer.Get(metricsTrailerKey)
		if len(baggageStrings) == 0 {
			return err
		}
		for _, baggageString := range baggageStrings {
			baggageBytes := []byte(baggageString)
			metricsBaggage := &metricspb.Baggage{}
			unmarshalErr := metricsBaggage.Unmarshal(baggageBytes)
			if unmarshalErr != nil {
				logger.Error("unable to unmarshal metrics baggage from trailer", tag.Error(unmarshalErr))
				continue
			}
			for counterName, counterValue := range metricsBaggage.CountersInt {
				ContextCounterAdd(ctx, counterName, counterValue)
			}
		}
		return err
	}
}