docker external network,connecting to docker external network,composer

The purpose of the this post is to learn how to connect a docker service to the existing or already created docker network. We will be creating a docker network and write the docker-compose.yml file with a service connecting to external network.

Lets create one docker network with overlay driver. For simplicity you may opt not to not use the driver and subnet option that I am using here in network creation.

docker network create --driver overlay --subnet10.0.9.0/24 myexternal-network

Now lets crate a docker docker-compose.yml file and add the external network to it.

docker-compose.yml

version:"3.4"
networks:
     myexternal-network:
         external: true

services:
   myapp:
       image: imagename
       networks:
           - myexternal-network

So in the networks we usually define a network but here we added a network and represented it as external. adding the network to services are the same like we do for other networks.

Note:
As we are using the external network it must be already available before running the docker service else will throw warning message.

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