Fundamentals of Container Networking
Tags: aws, containerapps, networking, kubernetes
Published: 2023-01-09 07:37:25

Containers are successor to virtual machines, they are abstracted within the operating system level by the container engine. Container networking is a crucial aspect of modern software development and deployment, as it enables communication between containers, microservices, and applications in a containerized environment.In this article, we will explore the basics of container networking and how it works, types, as well as its benefits and challenges.

**What is container networking?**
Containers are a lightweight and portable way to package and deploy applications, as they include all the necessary libraries, dependencies, and runtime environment in a single package. 
Container runtimes use network drivers to define how containers connect with each other by controlling the **_host iptables_**, as well as with external networks and services

Follow the guidelines to setup a docker engine: [Docker Installation](https://www.digitalocean.com/community/tutorials/how-to-install-and-use-docker-on-ubuntu-20-04)

Verify the Docker engine Installation

![Docker version](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/20adjtnqa066vmu12rdn.png)

**Types of Container networking**
There are several container networking models, each with its own benefits and limitations. 

![Types of Container network](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/ka8pfn7m90cnvnzj0oyu.png)

1. None: With this type of networking for containers, a network stack is provided to the container. Although it only gets a loopback interface, the container lacks an external network interface. When no networking is utilized. This model can be used to setup containers for future network connections, allocate containers without external contact, and test containers.

2. Bridge: This is the default network type for docker, in which a network bridge is created on the host system to connect the containers to the host network. To enable single-host networking, bridge networking makes use of iptables for NAT and port mapping
![Bridge](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/6nynp9x8lzy60x36z8iz.png)
This shows the default docker bridge network is 172.17.0.0/16, all containers belong to this network by default
![Ubuntu container](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/n8wk9lz1wzuc3w1bacyd.png)
![Test Container](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/saqbvvdbj7h72vxrcjgx.png)
This shows ubuntu container was assigned an ip address within the docker bridge network(172.17.0.2/16)

3. Host: A newly built container can interact with the host to share a network namespace. There is no longer a need for NAT because it offers better performance that is practically as fast as bare metal networking. Ports conflict may result from this type of networking model.
![Host container](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/67pc2c652gwgke3tb8dp.png)

![Host network](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/qcuvt2w2fgb6jyvw9c9l.png)
The container has access to the host's network interfaces.

4. Overlay: Another popular type is the overlay model, which creates an additional layer of abstraction on top of the host network to connect the containers. This model allows containers to communicate with each other across multiple hosts using protocols VXLAN, Calico, making it suitable for distributed systems such as kubernetes. The overlay model is more complex to set up and manage than the bridge model, but it offers better isolation and security

**Benefits of container networking**
There are several benefits to using container networking:

1. Portability: Containers are designed to be portable, and container networking allows them to communicate and interact with each other and with the host system regardless of the underlying infrastructure. This makes it easier to deploy and scale applications across different environments and platforms.

2. Isolation: Container networking enables the isolation of different applications and services within the same host system, reducing the risk of interference and conflicts. This is especially useful in multi-tenant environments where multiple applications and services are running on the same host.

3. Resource efficiency: Containers are lightweight and use fewer resources than traditional virtual machines, and container networking allows multiple containers to share resources and infrastructure. This makes it easier to optimize resource usage and reduce costs.

**Challenges of container networking**

Despite the benefits of container networking, there are also several challenges to consider:

1. Complexity: Container networking can be complex to set up and manage, especially in large and distributed systems. It requires a good understanding of networking concepts and technologies, as well as the underlying infrastructure and environment.

2. Security: Container networking introduces additional security risks, as it allows containers to communicate with each other and with external networks. It is important to implement appropriate security measures and controls to prevent unauthorized access and attacks.

3. Performance: Container networking can impact the performance of applications and services, especially in high-traffic environments. It is important to monitor and optimize the container networking configuration and performance to ensure the best possible user experience.

Your comments and feedbacks will be appreciated, wactchout for the next article on Container Network Management