Jump right into Kubernetes development with career-focused lessons and hands-on practice.

DevOps for Developers

Kubernetes is a powerful container management tool that's taking the world by storm. This detailed course will help you master it.

In this course, you'll start with the fundamentals of Kubernetes and what the main components of a cluster look like. You'll then learn how to use those components to build, test, deploy, and upgrade applications, as well as how to achieve state persistence once your application is deployed. You'll also learn how to secure your deployments and manage resources, which are crucial DevOps skills.

By the time you're done, you'll have a firm grasp on what Kubernetes is, as well as the skills to deploy your own clusters and applications with confidence.

A Practical Guide to Kubernetes

# Looking into the syntax
We can accomplish a similar result as the one using `kubectl expose` through the `go-demo-2-svc.yml` specification shown below:

apiVersion: v1
kind: Service
metadata:
  name: go-demo-2
spec:
  type: NodePort
  ports:
  - port: 28017
    nodePort: 30001
    protocol: TCP
  selector:
    type: backend
    service: go-demo-2

* **Lines 1--4:** Since we have already discussed the meaning of `apiVersion`, `kind`, and `metadata`, we’ll jump straight into the spec section.
 
* **Line 5:** Since we have already explored some of the options through the `kubectl expose` command, the `spec` should be relatively easy to grasp.

* **Line 6:** The `type` of the Service is set to NodePort, meaning that the ports will be available both within the cluster as well as from outside by sending requests to any of the nodes.


* **Lines 7--10:** The `ports` section specifies that the requests should be forwarded to the Pods on port `28017`. The `nodePort` is new. Instead of letting the Service expose a random port, we set it to the explicit value of `30001`. Even though this is not a good practice, let’s demonstrate that option as well. The protocol is set to `TCP`. The only other alternative would be to use `UDP`. We could have skipped the protocol altogether since `TCP` is the default value but, sometimes, it is a good idea to leave things as a reminder of an option.

* **Lines 11--13:** The `selector` is used by the Service to know which Pods should receive requests. It works in the same way as ReplicaSet selectors. In this case, we define that the Service should forward requests to Pods with labels type set to `backend` and `service` set to `go-demo`. Those two labels are set in the Pods `spec` of the ReplicaSet.



# Creating the Service
Now that we know in the definition, we can proceed and create the Service. 

Learn to create Services through declarative syntax.

Creating Services through Declarative Syntax

Looking into the syntax