Docker List Networks

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In this guide, we'll explore the art of listing Docker networks with examples.

Why List Docker Networks? 

Listing Docker networks becomes crucial for several reasons: 

Verification: To ensure a newly created network is up and running. 

Clean-Up: To identify and remove any unnecessary or unused networks. 

Configuration Check: To inspect the details of specific networks. 

Troubleshooting: Helps in diagnosing connection or configuration issues. 

Listing Docker Networks 

To list all the Docker networks on your host, simply run:

docker network ls

When you run this command, the output will look something like this:

NETWORK ID          NAME                DRIVER              SCOPE
16fa3b677b63        bridge              bridge              local
292f1b95f4fa        host                host                local
adcf8fc67a2d        none                null                local

Understanding the Output:

NETWORK ID: A unique identifier for the network. 

NAME: The name of the network. 

DRIVER: The network driver being used. 

SCOPE: Specifies the scope of the network, which could be local, global, or swarm.

Default Networks

When you install Docker, it automatically creates three default networks. You can see them in the list above: 

bridge: The default network that a container gets attached to if no network is specified. It's a private internal network on your host, and containers get an internal IP from it. 

host: Removes network isolation between the container and the Docker host. Use with caution! 

none: A container-specific network stack. No external or internal communication is allowed unless explicitly configured.

Creating and Listing Custom Networks

You can create your custom network using the docker network create command. For instance:

docker network create my_custom_network

After creation, running docker network ls will now also show:

$ docker network ls
....
c90f3b345e7f        my_custom_network   bridge              local

Docker Network Filtering

Filtering by Network Name:

If you're looking for a network named "my_custom_network":

$ docker network ls --filter=name=my_custom_network
NETWORK ID     NAME               DRIVER    SCOPE
1a2b3c4d5e     my_custom_network  bridge    local

Filtering by Network ID:

Let's say you have a specific network ID (e.g., "1a2b3c4d5e"):
$ docker network ls --filter=id=1a2b3c4d5e
NETWORK ID     NAME               DRIVER    SCOPE
1a2b3c4d5e     some_network       bridge    local

Filtering by Network Driver:

To fetch all networks using the "bridge" driver:
$ docker network ls --filter=driver=bridge
NETWORK ID     NAME               DRIVER    SCOPE
1a2b3c4d5e     network1           bridge    local
6f7g8h9i0j     network2           bridge    local

Displaying Network IDs Only

To list only the IDs of the Docker networks:

docker network ls --format '{{.ID}}'

For example:

$ docker network ls --format '{{.ID}}'
2f259bab6f03
578a065dfead
c678f4a8f8d5

Conclusion

In this guide, we have learned how to list default Docker networks, how to filter docker networks, and how to create and list custom Docker networks with examples.

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