Updated June 14, 2023
Introduction to Kubernetes Networking
As we know, Kubernetes helps us automate our application’s deployment, maintenance, operations, scheduling, and various operations across the different clusters. Moreover, Kubernetes networking, as the name suggests, allows us to communicate with other Kubernetes components and also with each other; also, Kubernetes is very much different from any other networking platform because it removes to do manual mapping of host port to the container ports. Kubernetes contains different components which describe the working of Kubernetes networking; in the coming section of the tutorial, we will see in detail how it works and its implantation for better understanding and clarity for beginners.
What is Kubernetes Networking?
As we have already discussed, Kubernetes networking allows us to communicate with the different components. Also, networking in Kubernetes is very different; it removes a lot of manual work for the developers. In Kubernetes, we have so many core components which need to understand to get the concept behind Kubernetes networking; let’s see a few of the points below –
- Master Node
- Worker node
- Other Kubernetes components
These are the few points which majorly include in the Kubernetes networking concept. Kubernetes networking developed by Google, there are a few points which we should keep in mind –
1. An administrator uses Kubernetes cluster networking to move between private, public, and hybrid cloud infrastructure.
2. By the use of Kubernetes networking enables us to communicate between the components and other applications as well.
We also have different types of networking within Kubernetes, which we will discuss in the coming section of the tutorial.
How does Networking Work?
As we know, we have different components within the Kubernetes platform, such as containers, Pods, applications, and nodes, and these all use different types of methods to communicate with one another. So let’s take a look at the types of networking, which are as below –
- Pod-to-service communication
- Pod-to-Pod communication
- external-to-service communication
Now let’s take a closer look at the essential or core components of Kubernetes networking which allows us to have external traffic inside the Kubernetes cluster –
a. LoadBalancer: This component allows us to connect with the service externally to the internet, so in such a scenario, it will help us to forward all the external traffic to the respective service, also; as we know in Kubernetes, we have specific IP to every service.
b. ClusterIP: This is the default service of Kubernetes which allows us to communicate within Kubernetes, which is internal communication, so for external traffic, it uses a proxy to communicate. This service is helpful when we want to debug the service or want to show interactive Kubernetes dashboards.
c. NodePort: This service allows us to open ports on the virtual machine, and after this, traffic gets forwarded to these ports. This is one of the most used services.
d. Ingress: A service or a controller allows us to route the traffic to the service using a load balancer.
Network Administrators Implement:
This section will see the implementation of Kubernetes networking; we have different ways to do this. In this section, we will see 4 ways by which we can do this; Gartner gives it in 2019 in one of his reports, so let’s get started;
a. Dell EMC: These approaches support cloud-native and traditional applications, with integrated support for Kubernetes and its containers. It is a cloud platform.
b. Cumulus NetQ: It is a fabric validation system based on telemetry; this helps us have visibility inside the container during deployments.
c. VMware NSX-T: It is a security and network virtualization platform that helps us in multi-hypervisor and multi-cloud environments, including native container networking.
Kubernetes Network Model:
Let’s look at the Kubernetes networking model in detail; it consists of various components, including the important ones below.
a. Master node: This is the main node, which manages the worker node and controls the pod deployment.
b. Worker node: These are the server’s nodes, which help us run the Kubernetes components, including application containers and proxies within pods.
c. Service: It is an abstraction layer in Kubernetes, which has its IP address and ports, which act as an internal load balancer or proxy for the requests across the pods.
d. Pod: This is one of the essential components of Kubernetes; it also contains its IP address, which can contain multiple or single containers.
e. Other Kubernetes components: Other components such as API Server, Kubelet, etc.
Kubernetes Services and DNS
Kubernetes service is a logical, abstract layer, which helps us to connect the sets of pods to the specified abstract service name and the IP address; let’s take a few points to understand the Kubernetes service in detail –
1. Kubernetes service provides the route between the pods and the discovery.
2. Helps us to connect a set of pods.
3. Kubernetes service helps us to connect our application frontend to its backend.
4. Services use selectors and labels, which help us match the pods with the other application.
5. It consists of various types of attributes; some of which are mentioned below –
- Port definition.
- Label, which helps us to connect to the pods.
- The port number and assigned cluster IP address.
- Mapping of incoming ports to the outcoming ports.
Tools for Kubernetes Networking
- Flannel: It is a virtual network designed for Kubernetes; it runs an agent known as flanneld.
- Project Calico: This tool provides us with strong access control lists and network policy management; by the use of this, we can easily configure direction, inbound and outbound rules, protocol, and other attributes also.
- Canal: It combines Flannel and Calico to create and network solution. In simple words, it combines Flannel architecture with Calico policy management. In addition, it is a deployment tool for configuring both tools, such as Flannel and Calico.
Networking is an essential part that needs to be understood before getting started with Kubernetes; go through the tutorial for a better sense of clarity and understanding, and get started with Kubernetes networking for communication.
This is a guide to Kubernetes Networking. Here we discuss the introduction, working, tools, Kubernetes services, and DNS. You may also have a look at the following articles to learn more –