Kubernetes is a powerful tool. It can help you manage complex applications and provide you with the ability to easily automate tasks involved in managing them. In this course, we will start exploring Kubernetes from a beginner's standpoint. We will discuss what Kubernetes is and what it does, and we will work with some of the basic functionality of Kubernetes hands-on. We will build a simple Kubernetes cluster. We will also deploy a sample microservice application to the cluster in order to explore how Kubernetes can help easily manage such applications.

A Practical Guide to Kubernetes

# Exploring the AWS ELB

We need a way to access the cluster. So far, we saw that we can, at least, interact with the Kubernetes API. Every time we executed `kubectl`, it communicated with the cluster through the API server. That communication is established through AWS Elastic Load Balancer (ELB). Let's take a quick look at it.

The **output**, limited to the relevant parts, is as follows.

{
  "LoadBalancerDescriptions": [
    {
      ...
      "ListenerDescriptions": [
        {
          "Listener": {
            "InstancePort": 443, 
            "LoadBalancerPort": 443, 
            "Protocol": "TCP", 
            "InstanceProtocol": "TCP"
          }, 
          ...
      "Instances": [
        {
          "InstanceId": "i-01f5c2ca47168b248"
        }, 
        {
          "InstanceId": "i-0305e3b2d3da6e1ce"
        }, 
        {
          "InstanceId": "i-04291ef2432b462f2"
        }
      ], 
      "DNSName": "api-devops23-k8s-local-ivnbim-1190013982.us-east-2.elb.amazonaws.com", 
      ...
      "LoadBalancerName": "api-devops23-k8s-local-ivnbim", 
      ...

Judging from the `Listener` section, we can see that only port `443` is opened, thus allowing only SSL requests. 

The three instances belong to managers. We can safely assume that this load balancer is used only for the access to Kubernetes API. In other words, we are still missing access to worker nodes through which we'll be able to communicate with our applications. We'll come back to this issue in a moment.

The entry that matters, from user's perspective, is `DNSName`. That is the address we need to use if we want to communicate with Kubernetes' API Server. Load Balancer is there to ensure that we have a fixed address and that requests will be forwarded to one of the healthy masters.

Finally, the name of the load balancer is `api-devops23-k8s-local-ivnbim`. It is important that you remember that it starts with `api-devops23`. You'll see soon why the name matters.

## Looking into the kubectl Configuration
We can confirm that the `DNSName` is indeed the door to the API by examining `kubectl` configuration.

In this lesson, we will figure out how the different components in our cluster are communicating with each other and what we need to establish our communication with the worker nodes.

Accessing the Cluster: Understanding the Protocol

Exploring the AWS ELB