Types Of Kubernetes Services
In Kubernetes, there are 3 types of services to provide discovery and routing between pods.
1. ClusterIP: It is the default service and its visibility is cluster internal which means it’s not possible to use clusterIP service to reach a micro-service from the internet from outside the cluster.
2. NodePort: NodePort extends the ClusterIP service and its visibility is internal and external to the cluster. You can set a NodePort using the NodePort property, this is the port that the service will listen on from outside the cluster. There is one requirement of using NodePort which is nodes must have public IP addresses. The port must be in the range between 30000 and 32767 and if you don’t specify the NodePort value Kubernetes will assign it randomly.
3. LoadBalancer: It operates at the transport level (TCP) that is at level 4. It means that is unable to make decisions based on content and it uses a simple algorithm such as a round-robin across the selected paths. Whereas Ingress operates at the application level which is at level 7. It is able to make decisions based on the actual content of each message. More intelligent load-balancing decisions and content optimizations. In other words, Ingress is like a LoadBalancer but more intelligent.
For our article, we’ll use NodePort service for service discovery.
Kubernetes – NodePort Service
NodePort service in Kubernetes is a service that is used to expose the application to the internet from where the end-users can access it. If you create a NodePort Service Kubernetes will assign the port within the range of (30000-32767). The application can be accessed by end-users using the node’s IP address.