What is the Kubernetes Service?
Kubernetes service is an open-source container orchestration framework that Google develops. It manages containers such as Docker containers. Kubernetes helps to manage containerized applications made of hundreds or thousands of containers. It also helps manage them in different environments such as physical machines, virtual machines, cloud environments, or even hybrid deployment environments.
What Problem does Kubernetes Service Solve?
The need for a Container Orchestration Tool
The more use of microservices increases container technology practice because the containers offer the best host service for small independent applications such as microservices. To manage those loads of containers across multiple environments using scripts and self-made tools can be really complex and even sometimes impossible, so that specific scenario causes the need for having container orchestration technologies.
Features Offer by those Orchestration tools
High availability or no downtime: High availability means that the application has no downtime, making it always accessible.
Scalability or High Performance: Scalability means that the application has high performance. It loads fast, and the user has a very high response rate from the application.
Disaster Recovery: If the infrastructure has some problems like data loss, server corruption, or something terrible happened with the server center. The infrastructure must have some mechanism to back up the data and restore it to the latest state. So, the application doesn’t lose any data. The containerized applications can run from the most recent state after the recovery and all of these functionalities that container orchestration technologies like Kubernetes offer.
Essential Fundamental Components of Kubernetes Service
Kubernetes Service has tons of components; some of them are mentions here:
POD: The simple server or a virtual machine and the basic or smallest component is POD. It is an abstraction over a container. POD component allows to creates a running environment. It is an application that has its container and database. It is usually meant to run one application container inside of it. This component allows running multiple containers inside of it. But usually, it is only the case if the user has one main application container and a helper container or some side service that has to run inside of that POD.
How Containers Communicate?
Kubernetes service offers out of the box a virtual network, which means each POD gets its IP address, not the container the POD gets the IP address, and each POD can communicate with each other using that IP address. If a database is crashed, a new database will automatically create and assign a new IP address.
As mentioned before, in a Kubernetes cluster, each POD gets its internal IP address, but the PODs in Kubernetes are ephemeral, which means when a POD will restart, the old one will die, and the new one get started in its place and gets a new IP address. The service provides a stable IP address that stays even when the POD dies. Service also provides load balancing because when there is a POD replica, for example, a user has three replicas of a microservice application. The service will get each request targeted to the microservice application and then forward it to one of those PODs. So clients can call a single stable IP address instead of calling each POD individually.
The Kubernetes services are a useful abstraction for loose coupling for communication within the cluster.
Here are some different types of Kubernetes services, such as:
- Cluster IP Service
- Headless Service
- NodePort Service
- Load Balancer Service
Cluster IP Service: This is the default type of service, which means when a user will create without specifying a type, it will automatically take cluster IP as a type.
Headless Service: It is a simple service with no cluster IP address. Headless service not providing low balancing or proxying. Its job is to create and maintain DNS records for each of the PODS.
NodePort: It is part of mobility service resources only. It opens a specific port on the node.
Load Balancer Service: This service refers to efficiently distributing incoming network traffic across a group of backend servers/microservices.
Author: SVCIT Editorial
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