Docker Networking 101: Everything You Need to Know

Docker Network is a type of networking that enables you to build a Network of Docker Containers which is managed by a master node called the manager. By sharing packets of information, containers inside the Docker Network can talk to each other.

Network administrators in the Docker ecosystem have a heavy burden of knowledge when it comes to the virtualization platform-specific networking components. However, deploying a container is not a simple process. It needs to have good networking abilities in order to appropriately set up a container architecture. Docker Networking was developed as a solution to address this issue. 

If you’re looking for a docker consulting service provider, then you can contact SupportFly, whose dedicated team is available to serve any time of the day with extensive knowledge. We’ll also help you to understand Docker Network. So with this article, we’re going to explain what docker networking is, Its types, how it works, and so on. Read this blog to get deep knowledge about Docker networking.

What is Docker networking?

A network is a set of two or more devices that are able to communicate with each other either physically or digitally. The Docker network is a virtual network that Docker made so that Docker containers can communicate with each other. If two containers are executing on the same host machine, they are able to interact with each other even if the host machine’s ports are not open. Docker allows you to manage your Docker hosts on any platform you want, regardless of whether they operate under Windows, Linux, or a combination of the two operating systems.

Docker networking is about how these containers communicate with each other and with the outside world. Whether they stay in their own neighborhoods, share the same space, or build bridges across oceans, Docker provides the tools to make sure these containers can talk and work together effectively.

How Docker Networking Works

Docker’s networking system is based on the network stack of your host. Iptables rules are manipulated in order to direct traffic to the appropriate containers, which is how it works. Additionally, this separates the Docker networks from your host.

The most common tool for filtering packets in Linux is called iptables. When you add rules to iptables, they tell the network stack on your host how to route data as it goes through it. Docker networks add rules for filtering traffic that sends it to the program in your container. You don’t have to do anything to iptables because the rules are set up automatically.

Each Docker container has its own network namespace, which is a function of the Linux kernel that produces separate virtual networks. Containers also set up virtual network ports on your host, which lets them use your host’s network to talk to other containers outside of their namespace.

Also Read: Our blog post on how to install docker on windows

Advantages of Docker Network

Docker networking offers several advantages, contributing to the widespread adoption of Docker for containerized applications. Here are some key advantages:

Isolation and Security

Docker networks provide a level of isolation for containers, ensuring that each container operates independently. This enhances security by preventing direct interference or communication between containers unless explicitly configured.

Flexibility and Scalability

Docker supports a variety of network types, including bridge, overlay, host, and custom networks. This flexibility allows developers to choose the most suitable network model for their application’s architecture. Additionally, Docker’s networking capabilities scale seamlessly to support the growing needs of distributed and microservices-based applications.

Efficient Resource Utilization

In order to be lightweight and efficient with resources, containers share the base of the host system. Docker’s networking approach doesn’t introduce the overhead associated with traditional virtualization, enabling more containers to run on a single host without sacrificing performance.

Container Orchestration Support

Docker’s networking features are well-integrated with container orchestration platforms like Docker Swarm and Kubernetes. This ensures that containers can communicate effectively in orchestrated environments, facilitating tasks such as load balancing, service discovery, and dynamic scaling.

Easy Service Discovery

Docker automatically provides DNS resolution for containers on the same user-defined bridge network. Containers can discover and communicate with each other using container names, making service discovery straightforward and eliminating the need to manage IP addresses manually.

Cross-Platform Compatibility

Docker provides a consistent networking model across different operating systems, including Windows, macOS, and Linux. This cross-platform compatibility allows developers to create and test applications on their local machines and then deploy them in diverse environments without significant modifications.

Check Out: Our blog post on docker vs vagrant

Docker Network Types

When using Docker, networks are set up to allow for communication between containers and external services. In order for containers to have any kind of network connectivity, they need to be connected to a Docker network. The container’s current network connections determine the communication paths that are open to be used by the container.

Docker comes with Six different network drivers already built in, all of which implement essential networking functionality:

1. Bridge
2. Host
3. Overlay
4. IPvLAN
5. Macvlan
6. None

1. Bridge

Bridge networks connect your host computer to the container by establishing a software-based bridge between the two. Containers that are connected to the network are able to communicate with one another, but they are separated from those that are not connected to the network.

Each container on the network has its own unique IP address that is assigned to it. Containers are able to communicate on your local area network (LAN) as well as the internet since the network is bridged to your host. On your LAN, they will not exist as physical devices.

2. Host

Containers that operate in the host network mode share the network stack of the host computer without providing any form of isolation. Furthermore, they do not have their own IP addresses, and port bindings will be sent straight up to your host’s network interface. In other words, a container process that waits on port 80 will connect to <your_host_ip>:80.

3. Overlay

Docker hosts can participate in distributed networks known as overlay networks, which span many hosts. All of the containers that are now running on any of the hosts are able to communicate with one another because of the network, which does not require OS-level routing capabilities.

You can use overlay networks when you are running two distinct instances of Docker Engine with containers that need to directly communicate with each other. Overlay networks are used to implement the networking for Docker Swarm clusters. This enables you to create your own habitats that are similar to Swarm.

4. IPvLAN

IPvLAN is a powerful driver that gives you precise control over the IPv4 and IPv6 addresses that are issued to your containers, in addition to providing layer 2 and layer 3 VLAN tagging and routing capabilities.

When combining containerized services with an existing physical network, this driver can be beneficial as it allows for seamless communication between the two. IPvLAN networks are each given their own interfaces, which, in comparison to bridge-based networking, results in significant improvements in performance.

5. macvlan

Another advanced option, macvlan makes it possible for containers to appear as real devices while they are connected to your network. In order for it to work properly, a one-of-a-kind MAC address is allotted to each container in the network.

If you choose to use this kind of network, you will need to assign one of the physical interfaces on your host computer to the virtual network. The larger network must also be configured correctly in order to accommodate the possibly high number of MAC addresses that could be generated by an active Docker host that is running a large number of containers.

6. None

When you use “none network” in Docker, you tell it that your container doesn’t need a network connection. When starting a container, you can use the –network none flag to prevent the container’s function from communicating with other containers or the host system.

Containers will not be given their own unique IP addresses. We cannot enter these contaminants from the outside or from any other containment because they are completely sealed off.

Which Network Type Should I Use?

For the vast majority of situations, bridge networks are the best available choice. With their own IP addresses and DNS names, containers in the network can talk to each other. They can also connect to your host’s network and get to the internet and your LAN.

You should use a host network if you want to connect ports directly to your host’s interfaces and don’t care about keeping the network separate. They let apps that run in containers work like network services that run directly on your server.

When containers on different Docker systems need to talk to each other directly, they need overlay networks. You can set up your own high-availability global setups with these networks. Macvlan networks are helpful when containers need to show up as a real device on your host’s network, like when they run an app that checks network data. IPvLAN networks are a more complicated choice when you need to be very detailed about IP addresses, tags, and routing for containers.

Docker also works with network tools from outside sources, which add more running modes to the networking system. Two of these are Kuryr, which uses OpenStack Neutron to run its networking, and Weave, an overlay network that focuses on finding services, keeping them safe, and handling errors.

Lastly, Docker networking is always available at the container level. If you set the network of a container to “none,” it will not have any networking at all. It won’t be able to talk to its neighbors, use your host’s services, or connect to the internet. By isolating apps that aren’t likely to need to join, this helps improve security.

Also Read: Our blog post on docker inspect

Launch a Container on the Default Network

1. Understanding the Docker Network Command

Docker Network is the primary command that will enable you to construct, manage, and configure your Docker Network. Use this command. Let’s have a look at the several subcommands that may be used in conjunction with the Docker Network command. To learn more about how to connect a container to a network using Docker and how to create a network using Docker.

sudo docker network

raunak@iamrj846:~$ sudo docker network
[sudo] password for raunak:
Usage: docker network COMMAND
Manage networks
Commands:
connect Connect a container to a network
create Create a network
disconnect disconnect Disconnect a container from a network
inspect Display detailed information on one ог more networks
ls List networks
prune Remove all unused networks
rm Remove one or more networks
Run 'docker network COMMAND --help' for more information on a command.
raunak@iamrj846:~$

We are going to go through all of the Network subcommands one by one.

2. Using Docker Network Create command

We are able to set up our very own docker network and install containers inside of it with the help of the “Create” command. 

sudo docker network create --driver < driver-name> ‹bridge-name>

raunak@iamrj846:~$ sudo docker network create --driver bridge demo-network
[sudo] password for raunak:
d32229a427c7c8a3120cbb07e1be8dc1c5673745407c8dbbeb3aaa2b0b8c2f60
raunak@iamrj846:~$_

3. Using the Docker Network Connect command

You may connect a Docker Container that is now running to an already established network by using the “Connect” command.

sudo docker network connect ‹network-name> <container-name or id>

In this example, we are going to connect an Ubuntu Container to the Docker network Bridge that we established in the last stage. 

raunak@iamrj846:~$ sudo docker network connect demo-network 7761e1e6fd88
raunak@iamrj846:~$

4. Using the Docker Network Inspect command

You are able to gain insight into the workings of a Docker Network by utilizing the Network Inspect command.

sudo docker network inspect ‹network-name>

raunak@iamrj846:~$ sudo docker network inspect demo-network
[
{
"Name": "demo-network"
"Id":"d32229a427c7c8a3120cbb07e1be8dc1c5673745407c8dbbeb3aaa2b0b8c2f60",
"Created": "2020-10-29T18:35:11.518087546+05:30",
"Scope": "local"
"Driver": "bridge",
"EnableIPv6": false,
"IPAM" : {
"Driver": "default",
"Options": {},
"Config": [
{
"Subnet" : "172.18.0.0/16",
"Gateway": "172.18.0.1"
}

Additionally, you can see a list of all the Containers that are linked to the Network.

5. Using the Docker Network ls command

You may use the list command to get a complete listing of all the Docker Networks.

sudo docker network 1s

6. Using the Docker Network Disconnect command

Another way to remove a Container from the network is to use the disconnect command.

sudo docker network disconnect ‹network-name> <container-name>

7. Using the Docker Network rm command

By using the rm command, you can get rid of a Docker Network.

sudo docker network rm < network-name>

Take note that in order to successfully delete a network, you will first need to ensure that no container is presently referencing the network.

8. Using the Docker Network prune command

You may use the prune command to get rid of all of the Docker Networks that aren’t being used. 

sudo docker network prune

Conclusion

Docker’s networking system offers a variety of customizable settings for regulating the flow of communication between containers, their neighbors, and the Docker host. Containers on the same network can talk to each other by name or IP address.

Networking is done by a group of pluggable drivers that work with the majority of circumstances. Networks use the networking stack on your server, but namespaces keep them separate. Even though the separation is not as strong as the virtual networking architecture that is utilized by VMs, containers might nevertheless look like physical network devices when they are attached to a macvlan network. 

In this blog, Docker networking explained in detail and we also discussed Docker network types with the steps of launching a container on the Default Network. If you want to know more about Docker network you can click here to get more information.

Frequently Asked Questions (FAQ)

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