What is Kubernetes sessions - 4: Kubernetes Networking

In this post we discuss various aspects of Kubernetes networking, highlighting its native capabilities and innovative features that make it a powerful solution for microservices architectures. Think service discovery, load balancing, ingress, encryption, certificates, policies and multi cloud networking.

Connecting the dots …

As you may have understood from reading our previous article about workloads, Kubernetes has revolutionized the way we can deploy and manage containerized applications. Of course networking plays a critical role in how those work together. How easy is it to direct traffic to the correct endpoints? How do we guard that with policies? What tools does it give us for intrusion detection and mitigation?

This article will explore the innovative aspects of Kubernetes networking, focusing on its native building blocks and their benefits in comparison to traditional cloud networking solutions.

Service discovery and load balancing

Kubernetes has native capabilities for service discovery and load balancing, which are essential for consistent communication between application components. By operating at the application layer (Layer 7, or L7), Kubernetes eliminates the complexities associated with managing traditional networking at the transport layer (L4), which are defined on the ip level.

Kubernetes-native components, like Services and Endpoints, enable seamless interactions between application components, even if those endpoints are legacy applications. And with service meshes (e.g., Istio and Linkerd), this is extended across different clusters. Service meshes also provide advanced traffic control, such as blue/green load balancing, and monitoring features. (We will not go deeper into service meshes in this article, but we do recommend reading up on it.)

Ingress control: advanced traffic management and security

Kubernetes introduces the concept of Ingress as a declarative way to manage external access to services within the cluster. This approach simplifies traffic routing and enables advanced traffic management features, such as rate limiting and SSL termination.

Using Ingress resources and controllers, like NGINX and Traefik, users can define routing rules and incorporate additional functionality, such as intrusion detection, directly within the cluster. Moreover, the Ingress resource allows for service-specific configurations, enabling differentiation in security requirements.

With Ingress control Kubernetes offers an integrated approach to traffic management and security. For instance, a financial application may have stricter security requirements (e.g., compliance with OWASP guidelines) than a static website. With Kubernetes, users can easily configure different Ingress rules for each service, tailoring the security settings to each application's needs.

Network policies: traffic directionality and security

Kubernetes natively supports network policies on L7, allowing users to define and enforce traffic rules at the pod level. This feature provides a more user friendly and maintainable approach to network security and isolation compared to traditional cloud networking solutions, which operate on L4.

With building blocks like NetworkPolicy and Container Network Interface (CNI) plugins such as Calico and Cilium, users can create fine-grained rules for communication within the cluster. CNI plugins enable easy integration with various network providers, offering flexibility and adaptability to different cloud environments.

One example of how network policies can be used to enhance security is by isolating sensitive components within a cluster. Suppose an organization has a Kubernetes cluster hosting multiple applications, including a payment processing service. To reduce the risk of unauthorized access, the organization can create network policies that restrict communication to the payment processing service, allowing only specific application components to interact with it. This isolation reduces the attack surface and ensures that even if other components within the cluster are compromised, the payment processing service remains secure.

Encryption & certificates: enhanced security and simplified management

Kubernetes simplifies encryption and certificate management by offering built-in support for certificate distribution, rotation, and mTLS configuration. This approach bolsters the security of communication between cluster components, as opposed to traditional setups that often require significant manual effort.

Utilizing building blocks such as Secrets, cert-manager, and service meshes, Kubernetes ensures secure communication and efficient certificate management. Secrets safely store sensitive data like certificates, while cert-manager automates certificate distribution and rotation, saving time and minimizing human error.

Service meshes play a crucial role in enabling mTLS configurations, providing secure communication between application components. This additional layer of security further enhances the protection offered by Kubernetes, creating a more robust and secure cluster environment.

Multi-cloud and hybrid cloud networking

Kubernetes enables consistent deployment and management of applications across various cloud providers or hybrid cloud environments, abstracting away the underlying infrastructure and simplifying network connectivity, security, and performance management.

Concepts like federation and service meshes support multi-cloud and hybrid cloud networking scenarios. Federation allows users to manage multiple Kubernetes clusters as a single entity, while inter-cluster capable service meshes provide advanced features for managing communication between components in multi-cloud and hybrid cloud deployments.

For instance, a global organization may have a hybrid cloud setup, using both on-premises data centers and multiple cloud providers. By leveraging Kubernetes federation and service meshes, the organization can easily manage and deploy applications across its infrastructure, ensuring a consistent user experience and simplifying network management.


Kubernetes networking has brought significant innovations and improvements to the cloud computing landscape. With its native building blocks, Kubernetes offers a more flexible, scalable, and secure solution than traditional cloud networking. By understanding the key components and innovations in Kubernetes networking, organizations can leverage its benefits in a cloud agnostic way, and operate on a higher velocity. It makes a lot of sense to handle traffic inside a kubernetes cluster, avoiding L4 networking pains in cloud-native networking. 

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