Creating custom bridge networks in Docker - Visual Walkthrough

Process Flow - Creating custom bridge networks

Start

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Run: docker network create --driver bridge my_bridge

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Docker creates new bridge network

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Network available for containers

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Containers connect to custom bridge

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End

This flow shows how Docker creates a custom bridge network and how containers can connect to it.

Execution Sample

Docker

docker network create --driver bridge my_bridge

docker network ls

docker run -dit --name container1 --network my_bridge alpine sh

Creates a custom bridge network, lists networks, and runs a container connected to the custom bridge.

Process Table

Step	Command	Action	Result
1	docker network create --driver bridge my_bridge	Create a new bridge network named 'my_bridge'	Network 'my_bridge' created
2	docker network ls	List all Docker networks	Shows 'my_bridge' among default networks
3	docker run -dit --name container1 --network my_bridge alpine sh	Run container 'container1' attached to 'my_bridge'	Container 'container1' runs connected to 'my_bridge'
4	docker network inspect my_bridge	Inspect network details	Shows container1 connected to 'my_bridge'
5	docker network create --driver bridge my_bridge	Try to create network with existing name	Error: network with name 'my_bridge' already exists

💡 Execution stops after network creation and container run; duplicate network creation fails.

Status Tracker

Variable	Start	After Step 1	After Step 3	Final
Networks	default, bridge, host, none	default, bridge, host, none, my_bridge	default, bridge, host, none, my_bridge	default, bridge, host, none, my_bridge
Containers	none	none	container1 (on my_bridge)	container1 (on my_bridge)

Key Moments - 2 Insights

Why does the second 'docker network create' command fail?

Because a network named 'my_bridge' already exists as shown in execution_table step 5, Docker prevents duplicate network names.

How do we know the container is connected to the custom bridge network?

In execution_table step 4, inspecting 'my_bridge' shows 'container1' connected, confirming the container uses the custom network.

Visual Quiz - 3 Questions

Look at the execution table, what is the result of step 2?

A Shows 'my_bridge' among default networks

B Creates a new container

C Deletes the network

D Fails with error

💡 Hint

Check the 'Result' column in execution_table row for step 2

At which step does the container 'container1' start running?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look at the 'Action' and 'Result' columns for when the container is created

If you rename the network in step 1 to 'custom_net', what changes in the execution table?

A The container connects to default bridge

B The container name changes

C The network name in step 1 and 2 results changes to 'custom_net'

D No changes at all

💡 Hint

Focus on the network name in the 'Command' and 'Result' columns of steps 1 and 2

Concept Snapshot

Create a custom bridge network with:
  docker network create --driver bridge <name>
List networks:
  docker network ls
Run container on custom network:
  docker run --network <name> ...
Avoid duplicate network names to prevent errors.

Full Transcript

This lesson shows how to create a custom Docker bridge network named 'my_bridge'. First, the command 'docker network create --driver bridge my_bridge' creates the network. Then, 'docker network ls' lists all networks including the new one. Next, a container named 'container1' is run attached to 'my_bridge' using 'docker run -dit --name container1 --network my_bridge alpine sh'. Inspecting the network confirms the container is connected. Trying to create the same network again causes an error because the name is already taken. Variables tracked include the list of networks and containers connected. Key points include understanding why duplicate network creation fails and how to verify container network connection. The quizzes test understanding of the execution steps and effects of changing network names.