Headless Services
Headless Services in Kubernetes comes with specifying the setting of `.spec.clusterIP` to None and doesn’t provide the load balancing features with single IP allocation. Instead it facilitates to have a direct connections to the pods individually. It facilitates with interfacing the external service discovery mechanisms. DNS records, DNS services that are managed by Kubernetes provides endpoint IP’s for these Headless Services.
Headless Service With Selector
Deployments are usually used for stateless applications. However, you can save the state of deployment by attaching a Persistent Volume to it and make it stateful, but all the pods of deployment will be sharing the same Volume, and data across all of them will be the same. SatefulSet is a Kubernetes resource used to manage stateful applications. It manages the deployment and scaling of a set of Pods and provides a guarantee about the ordering and uniqueness of these Pods.
Example
apiVersion: v1
kind: Service
metadata:
name: my-service
spec:
clusterIP: None
selector:
app: my-app
ports:
- name: http
port: 80
targetPort: 8080
When we are using the type of service you will use, you need to give the name “clusterIP: None”.
Headless Service Without Selector
On without using the selectors features kubernetes doesn’t able to create the ENdpointSlice objects. The configuration of DNS depends on the type of service, some of them discussed as follows:
- For ExternalNames services, It configures DNS CNAME records.
- For other types, DNS will generates A or AAAA records for mapping to all IP addresses of ther Service’s ready endpoints.
What are Kubernetes Services? | Complete Guide
In Kubernetes, each pod is assigned its IP address but the pods are ephemeral that is they can be destroyed easily and when a new pod is created in place of them a new IP address is assigned to them. Here the role of services comes into the picture. A service is like a permanent IP address assigned to a pod. A service IP address is stable. So instead of sending a request to a pod, the client requests a service, and the service forwards that request to the desired pod. Services also help in load-balancing.
Table of Content
- What Are Services in Kubernetes?
- How do Kubernetes Service Work?
- How do You Define A Kubernetes Service?
- Port Definitions
- Services Without Selectors
- EndpointSlices
- Application Protocol
- Multi-Port Services
- Load Balancers With Mixed Protocol Types
- Choosing Your Own IP Address
- Choosing Your Own Port
- Types of Services
- How do You Access A Kubernetes Service? A Step-By-Step Guide
- Headless Services
- How to Create and Use A Kubernetes Service to Expose Your Application?: A Step-By-Step Guide
- What are the Differences between Kubernetes Service vs pod?
- What are the Differences between a Service and a Deployment?
- What are the Differences of Docker Service and Kubernetes Service?
- Discovering services
- Kubernetes Service – FAQs