instruction: Create a comprehensive Dockerfile for networking applications with best practices
output: ```dockerfile
  from the client might be routed to a different node.If you configure a service to use DNS round-robin (DNSRR) service discovery,
  there is not a single virtual IP. Instead, Docker sets up DNS entries for the
  service such that a DNS query for the service name returns a list of IP
  addresses, and the client connects directly to one of these.DNS round-robin is useful in cases where you want to use your own load
  balancer, such as HAProxy. To configure a service to use DNSRR, use the flag
  --endpoint-mode dnsrr when creating a new service or updating an existing
  one.Customize the ingress networkMost users never need to configure the ingress network, but Docker allows you
  to do so. This can be useful if the automatically-chosen subnet
  conflicts with one that already exists on your network, or you need to customize
  other low-level network settings such as the MTU, or if you want to
  enable encryption.Customizing the ingress network involves removing and recreating it. This is
  usually done before you create any services in the swarm. If you have existing
  services which publish ports, those services need to be removed before you can
  remove the ingress network.During the time that no ingress network exists, existing services which do not
  publish ports continue to function but are not load-balanced. This affects
  services which publish ports, such as a WordPress service which publishes port
  80.Inspect the ingress network using docker network inspect ingress, and
  remove any services whose containers are connected to it. These are services
  that publish ports, such as a WordPress service which publishes port 80. If
  all such services are not stopped, the next step fails.Remove the existing ingress network:
  
  $ docker network rm ingress
  
  WARNING! Before removing the routing-mesh network, make sure all the nodes
  in your swarm run the same docker engine version. Otherwise, removal may not
  be effective and functionality of newly created ingress networks will be
  impaired.
  Are you sure you want to continue? [y/N]
  Create a new overlay network using the --ingress flag, along with the
  custom options you want to set. This example sets the MTU to 1200, sets
  the subnet to 10.11.0.0/16, and sets the gateway to 10.11.0.2.
  
  $ docker network create \
   --driver overlay \
   --ingress \
   --subnet=10.11.0.0/16 \
   --gateway=10.11.0.2 \
   --opt com.docker.network.driver.mtu=1200 \
   my-ingress
  
  NoteYou can name your ingress network something other than
  ingress, but you can only have one. An attempt to create a second one
  fails.Restart the services that you stopped in the first step.Customize the docker_gwbridgeThe docker_gwbridge is a virtual bridge that connects the overlay networks
  (including the ingress network) to an individual Docker daemon's physical
  network. Docker creates it automatically when you initialize a swarm or join a
  Docker host to a swarm, but it is not a Docker device. It exists in the kernel
  of the Docker host. If you need to customize its settings, you must do so before
  joining the Docker host to the swarm, or after temporarily removing the host
  ```