docs(docker-compose): Explain `NAT` overhead in docker-compose (#176)

docs(docker-compose): Explain `NAT` overhead in docker-compose overlay vs host networks

Signed-off-by: Ryan Russell <git@ryanrussell.org>

contrib/docker/README.md

@@ -53,7 +53,16 @@ OK
 
 ## Step 3
 
-Continue being great and build your app with the power of DragonflyDB!
+Continue being great and build your app with the power of DragonflyDB!  
+
+## Tuning Dragonfly DB
+If you are attempting to tune Dragonfly DB for performance, consider `NAT` performance costs associated with containerization.  
+> ## Performance Tuning
+> ---
+> In `docker-compose`, there is a meaningful difference between an `overlay` network(which relies on docker `NAT` traversal on every request) and using the `host` network(see [`docker-compose.yml`](https://github.com/dragonflydb/dragonfly/blob/main/contrib/docker/docker-compose.yml)).  
+>    
+> Fore more information, see the [official docker-compose network_mode Docs](https://docs.docker.com/compose/compose-file/compose-file-v3/#network_mode)  
+>    
 
 ### More Build Options
 - [Docker Quick Start](/docs/quick-start/)

contrib/docker/docker-compose.yml

@@ -6,6 +6,10 @@ services:
       memlock: -1
     ports:
       - "6379:6379"
+    # For better performance, consider `host` mode instead `port` to avoid docker NAT.
+    # `host` mode is NOT currently supported in Swarm Mode.
+    # https://docs.docker.com/compose/compose-file/compose-file-v3/#network_mode
+    # network_mode: "host"
     volumes:
       - dragonflydata:/data
 volumes: