The beginning of a journey with Kubernetes - cluster architecture

I'm starting my Kubernetes journey and wanted to document and blog about what I'm learning, to help myself get more acquainted with the content while I learn. I'm currently studying with Kodekloud's CKA course so I will be documenting my notes from there.

I don't have any clear idea of how I'll go about it - my main goal is to try to explain what I've learnt to help myself better understand and retain the information in the process of recapping what I've studied.

First day of this, I have notes from the first video on the core concepts in Kubernetes.

The video goes over an analogy of a ship operation, carrying cargo containers, to illustrate cluster architecture. The main idea is that there is a master/control plane node managing the cluster, while there are a number of worker nodes carrying the containers.

Here are some of the notes I have on this analogy, relating the different components like the controllers, etcd, the scheduler, the kube API server, and the kubelet, to the cargo ship operations analogy.

• Master/control plane node doing all the managing of the cluster using control plane components
  
  
  
  
  • containers stored on the ship, which ship, what time it was loaded, etc - all stored in a highly available key-value store called the etcd cluster
  
  
  • cranes identifying containers that need to be on the ships - size, capacity, number of containers already on the ship - the schedulers
  
  
  • operations team, cargo team, communications, etc - controllers take care of different areas - manage node lifecycle, container replication, system stability. Node controlled, replication controller, controller manager
  
  
  • Kube API server - central hub for cluster communication and management, primary management component of k8s,
    
    
    
    
    • Kube API server is responsible for orchestrating all operations within the cluster
      
      
      
      
      • exposes the k8s API, which is used by external users to perform management operations on the cluster and controllers to monitor the state of the cluster and make necessary changes as required and by worker nodes to communicate with the server
      
      
      
      
      
      
    
    
    
    
    
    
  
  
  
  
  
  



• Cargo ships -
  
  
  
  
  • every ship has a captain that manages all the activity, liaising with master ship - this is the Kubelet, an agent that runs on each node in a cluster
    
    
    
    
    • listens for instructions from the kube API server and deploys or destroys containers on the nodes as required.
    
    
    • Kube API server periodically fetches status reports from the kubelet to monitor the status of nodes and containers on them
    
    
    
    
    
    
  
  
  
  
  
  

This is a really great way to get an overview of the main components in a kubernetes cluster, however I think I have a better idea of this after having already studied a couple things about kubernetes already - otherwise they can seem pretty abstract. So the more I go into the course and study more of the components individually, I'm sure these will all come together and become more and more familiar!

If you're also studying Kubernetes reach out to see if we'd have a good accountability buddy system!

- Catt