Prototype streaming healthcheck?

grpc.go

func monitorHealth(ctx context.Context, cc *grpc.ClientConn, cancelConn func()) {
	defer cancelConn()
	defer cc.Close()

	healthClient := grpc_health_v1.NewHealthClient(cc)

	wc, err := healthClient.Watch(ctx, &grpc_health_v1.HealthCheckRequest{})
	if err != nil {
		bklog.G(ctx).
			WithError(err).
			Error("could not start healthcheck stream")
		return
	}
	for {
		bklog.G(ctx).Debugf("awaiting healthcheck")
		resp, err := wc.Recv()
		if err != nil {
			errStatus, _ := status.FromError(err)
			switch errStatus.Code() {
			case codes.Unavailable:
				bklog.G(ctx).
					WithError(err).
					Debug("healthcheck returned unavaliable, client probably just exited?")
			default:
				bklog.G(ctx).
					WithError(err).WithField("status", errStatus.String()).
					WithField("status_code", errStatus.Code()).
					Error("healthcheck error")
			}
			return
		}
		if resp.Status != grpc_health_v1.HealthCheckResponse_SERVING {
			bklog.G(ctx).
				WithError(err).
				WithField("health_status", resp.Status).
				Warn("bad healthcheck status")
			return
		}

		bklog.G(ctx).Debugf("successful healthcheck recieved")
	}
}