)

const (
	Cancel = "cancelled"
	Error  = "error"
)

var (
	disconnectionTypeTag = monitoring.CreateLabel("type")

	// IstiodConnectionFailures records total number of connection failures to Istiod.
	IstiodConnectionFailures = monitoring.NewSum(
		"istiod_connection_failures",
		"The total number of connection failures to Istiod",
	)

	// istiodDisconnections records total number of unexpected disconnections by Istiod.

	defer cancel()

	upstreamConn, err := p.buildUpstreamConn(ctx)
	if err != nil {
		proxyLog.Errorf("failed to connect to upstream %s: %v", p.istiodAddress, err)
		metrics.IstiodConnectionFailures.Increment()
		return err
	}
	defer upstreamConn.Close()

	xds := discovery.NewAggregatedDiscoveryServiceClient(upstreamConn)
	ctx = metadata.AppendToOutgoingContext(context.Background(), "ClusterID", p.clusterID)

	defer cancel()

	upstreamConn, err := p.buildUpstreamConn(ctx)
	if err != nil {
		proxyLog.Errorf("failed to connect to upstream %s: %v", p.istiodAddress, err)
		metrics.IstiodConnectionFailures.Increment()
		return err
	}
	defer upstreamConn.Close()

	xds := discovery.NewAggregatedDiscoveryServiceClient(upstreamConn)