What are Kubernetes Services?
Kubernetes service is an abstract service that exposes an application on a set of Pods along with a policy to access them.
Kubernetes services are logical abstractions used on a group of pods in a cluster. A service assigns a single DNS name and a unique IP address to a set of pods that are responsible for performing various functions, including image processing, web processing, etc. Continue reading to know more about Kubernetes service and its uses.
Understanding Kubernetes Service
As Kubernetes service helps in exposing an application running on several Pods as a network service, you don’t need to modify the application. Yes, there is no requirement to modify the application to use the unfamiliar service discovery mechanism.
Various modern applications are mostly built using containers, which are microservices consisting of configurations and dependencies. Kubernetes is open-source software for managing these containers. These allow you to create, scale and deliver containerized applications faster.
Kubernetes Pods are built and destroyed to match the state of a cluster. Pods are not permanent. If you use a deployment to run the application, your Pods can be destroyed dynamically.
Each Pod gets its unique IP address, but in deployment, a group of Pods running at a point of time can be different from the group, which will run later.
The Difference Between a Service and a Deployment
In Kubernetes, a service is responsible for exposing an application to a set of pods that allow network access between the services and external processes, or within the cluster. At the same time, a deployment is a way to launch a Pod with containerized applications while making sure that the number of replicas is continuously running on the cluster.
Components of a Kubernetes Service
Kubernetes services use selectors and labels to match pods with other applications. The core components of a Kubernetes service are:
- The cluster IP address and assigned port number
- A label selector to locate Pods
- Port definitions
- Optional mapping of ports reaching a targetPort
Different Types of Kubernetes Services
Take a look at different types of Kubernetes Services:
- ClusterIP Service: A default type of service used to expose a service on an IP address in a cluster. Access is usually allowed within the cluster.
- Headless Service: These services do not require any kind of load balancing and is designed to only expose a single IP address. These can be defined with selectors and in this case, endpoint records are created in the API that changes the DNS to return addresses that point over Pods exposing the service.
- NodePort Service: NodePort are open ports that help in routing any traffic that reaches NodePort to the service. It is considered a foundation for other methods like load balancers.
- ExternalName Service: ExternalName Service returns a CNAME record and carries a defined value in the ExternalName. So, it is not accessed through a cluster IP address.
- Load Balancer Service: A Load Balancer service offers an equivalent to a clusterIP service and extends it to an external load balancer specific to the cloud provider. It is helpful for clusters that run on public cloud providers such as AWS or Azure.
How does Kubernetes Service Work?
As applications help span multiple containers deployed for various servers, operating them gets even more complicated. However, to solve this problem, Kubernetes offers an open-source API to manage how and where these containers will run.
Kubernetes arranges clusters of virtual machines while scheduling containers that can run on those virtual machines depending on their computing resources along with what is required for each container. The containers are accumulated into Pods – the basic unit for Kubernetes.
Kubernetes are also responsible for managing service discovery, tracking resource allocation as well as incorporating load balancing.
Uses of Kubernetes
Kubernetes is necessary for scheduling and deploying containers while scaling them to the user’s desired state and controlling their life cycles. So, let us take a look at the key uses of Kubernetes service –
1. Ensure portable workloads
As container applications are separated from their infrastructure, they become portable when they run on Kubernetes. You can easily shift them from local machines to production amidst hybrid and different cloud environments while also maintaining consistency among the environments.
2. Scale containers
Kubernetes service also helps define containerized applications and deploy them within a group of servers or clusters with Kubernetes. While scaling applications as per their desired state, Kubernetes also helps in monitoring and maintaining container health.
3. Building more extensible applications
A huge open-source community of companies and developers build extensions and plugins that aid in the security, management, and monitoring of Kubernetes.
Challenges Faced by Kubernetes Services
Installing, deploying, and managing Kubernetes isn’t so easy. Around 75% of users claim that there are many complexities in the implementation and operation of Kubernetes service. Companies must pay heed to factors like security, integration, multi-tenancy of investments while using Kubernetes.
Here are few challenges associated with the use of Kubernetes Service:
It is crucial to validate hosts using the correct settings and Linux operating system while installing Kubernetes.
The correct identity and security accesses should be supplied and integrated for storage purposes, networking, and container registry solutions whenever Kubernetes is used.
After deploying Kubernetes, it must be integrated with better solutions like security hardening, platform monitoring, and logging solutions. Therefore, organizations having several teams must ensure that resources are divided correctly and also, metering and chargeback solutions are configured efficiently.
When Kubernetes is properly functioning, every layer of the stack, namely Linux container host, Kubernetes along with the services running on its top, also needs regular updates.
How to Access a Kubernetes Service?
A Kubernetes service can be discovered in two ways:
- DNS – It is the most common and highly suggested method to discover services. To use this method, the user must first install a DNS server on the cluster. The DNS server keeps a check on the Kubernetes API, and when a new service is built, its name is available for requesting applications.
- ENV Variable – This method generally depends on the kubelet. It involves adding environment variables for every service that is active and for every node a Pod is running.
We hope you find the above information helpful and it thoroughly answers your query “What is Kubernetes service?” If you have any further queries, feel free to write it to us through the comment box below. Stay connected for more tech-guides.