Kubernetes Concepts for Beginners [8 k8s components]

In this article , We are going to cover Kubernetes Concepts for Beginners, Kubernetes Architecture, Kubernetes components and Tools for Kubernetes.

What is Kubernetes ?

Kubernetes is a brilliantly curated open-source platform that is focused on deployment and orchestration the containers. The Kubernetes offers a wide array of options that includes managing the container runtime, container-centric infrastructure, service discovery, loading balancing, self-healing mechanisms, container orchestrations, and much more.

Kubernetes also helps in the scaling, management, composition over application, deployment of the host’s cluster.  

In reality, Kubernetes is a lot more than just a container orchestrator and it can be incorporated as an operating system for many applications that follow cloud as native. Kubernetes can be executed just like a desktop app.

In short, it can replicate apps like Windows, Linux, and also macOS.  All you need is to incorporate and get started to manage the containers. 

The Kubernetes was created to reduce the pressure of orchestrating during the computing networking, storage and management. It will in turn enable quick operation of the application. Kubernetes is completely focused to manage container-centric workflow.

Kubernetes doing the early stage was used to run stateless applications but due to high popularity, Kubernetes are also now used for storage integration and are also now considered as the stateful application. The biggest benefit of Kubernetes is flexibility and versatility.

The Design Principles of Kubernetes 

The Kubernetes follows 3 design principles for each cluster. 

1. Effortless to use – Easy to operate and use, just need the few simple commands to get started. 

2. Extendable – Not favouring any provider and can be customized as per the need. 

3. Completely secure – Best and latest security to maintain zero loss of information.

Kubernetes Concepts for Beginners and Architecture

When we look at the configuration of Kubernetes, the overall environment consists of a Control Plane, Distributed Storage System, and Cluster Nodes. 

The control plane is responsible to maintain all the records of Kubernetes objects and it also manages the states of an object, responds towards cluster change, and tweaks the current state of the system to match the delivered state of objects. 

Kubernetes Concepts for Beginners [8 k8s components] 1

1. Kubernetes Control Plane 

The control plane is made of 3 powerful components I .e.Kube- APIServer, kube- controller-manager, and the kube-scheduler. All these 3 components can run on a single yet powerful master node. These components can also be replicated among multiple master nodes to boost availability. 

The API Server present in the control plane offers APIs to support lifecycle orchestration on multiple applications. This ensures the API server is accessible from outside the cluster as well. The authentication of clients is done via the API server.

2. Cluster Nodes

As discussed early, the Cluster Nodes are machines which execute the containers and are managed by the master nodes. The important controller in Kubernetes is the Kubelet, it is responsible to drive the overall execution of the containers layer. 

3. Pods and Services

Another crucial contact of Kubernetes is the pods, they are a key contract unit which comes in direct contact with the developers.  It is packed as a single application and can have multiple containers and storage units. The lifespan of pods is minimal, during the upgrading or scaling back, pods die because it is ephemeral. Horizontal autoscaling of pods is possible, it is also capable of performing rolling upgrades and deployments.

Type of Pods 

1. ReplicaSet – These are default and simple pods which ensure a particular number of pods are executing.  

2. Deployment – The declarative type of pods management via ReplicaSets is called Deployment. This also includes rollback, update mechanisms. 

3. Daemonset – It is a type of ensuring every node while executing pod. Daemonset is highly preferred for the cluster services that include log forwarding and monitoring the health. 

4. StatefulSet – This is a tailor made step up to manage the pods which must maintain state. 

5. Job and CronJob – These types of pods have a short-lived job and are usually on or off on a schedule.

4. Kubernetes Services

Kubernetes Services includes configuring a proxy to move the traffic towards pods.  Selectors are used in defining the pods used for services. This makes releasing new versions and including pods easy. The services are reachable inside the cluster via clusterIP service, other services include external access. Among all LoadBalancer types is the common type of deployment.

5. Kubernetes Networking

The Kubernetes Networking comes with a unique networking model that includes cluster-wide and pod to pod networking. The Container Network Interface follows a simple overlay network and makes use of the traffic encapsulation the containers can establish communication within the pod. The Pod has the same network namespace and IP address. The containers establish communication with the help of localhost effortlessly. 

6. Persistent Storage in Kubernetes

The concept of volumes is used in Kubernetes. The core volume is a directory with minimal data and can be accessed to a pod. Kubernetes supports various storage tapes that can be mixed and matched via pod. The pod can be consumed by containers and can also be restarted.  

7. Discovering and Publishing Services in Kubernetes

For a healthy Kubernetes environment, discovering services is crucial and it highly relies on integrated DNS service. The Kubernetes is used t0 create, update and delete DNS for services and pods. The 4 different types of services include 

  1. ClusterIP – This is for internal IP only and the service is reachable from within the cluster. It works as a default type. 
  1. NodePort – This showcases the services on every IP of node at a particular port. The developer has the freedom to set up a load balancer. 
  1. LoadBalancer – This shows the services externally using the load balancer of the cloud provider and is completely supported by the Kubernetes since the configuration is automated. 
  2. External Name – There is no proxy establishment and it is used to create service within the Kubernetes to show the external data stores similar to the database.

8. Use of Namespaces, Labels, and Annotations

The physical clusters are called namespaces and it is given to multiple users, teams, and prefects to work on.  This is done to prevent the team from getting into each other’s work. 

Labels are used to differentiate the resources in a single namespace and labels are used to describe the attributes to organize and select objects.  In addition to it, labels are used to promote work and watches, a perfect choice to incorporate in the user-oriented interfaces to map work structure. Annotations are used to add arbitrary non-identifying baggies to the objects. It is also used as a declarative configuration tool to build image information or contact information to update people.

Tools for Kubernetes

Here are the basic tools for Kubernetes which you should be aware of 

1. kubeadm – It is used to bootstraps a cluster and is designed in a smiling way for the news users which enables them to build clusters. 

2 Minikube – This too makes effortless execution of Kubernetes locally. If you are Mac users, use HomeBrew to use Minikube easily. 

3. Kubectl – This is an interesting tool which makes interaction with clusters easily. 

Apart from the above-mentioned tool for Kubernetes, there is a graphical dashboard that executes as a pod and it is used for general-purpose to get information about the cluster. 

Kubernetes architecture is the basic but the configuring and securing the Kubernetes cluster is challenging. Kubernetes provides needful tools to manage complex containers. You are free to select the operating system, runtime for the container, integration tooling, storage, application services, and much more.

Managing roles, access control, secured settings is another vital aspect of Kubernetes architecture. Finally, you get an option to run Kubernetes yourself or you can approach the vendor who can provide a needful supported version. 

Kubernetes offers flexibility and tremendous power to execute a containerized application based on your preference to react to the tweaks in your organization. Kubernetes lets you build, execute, deploy, manage the containerized application securely.

Conclusion:

We have covered Kubernetes Concepts for Beginners, Kubernetes Architecture, Kubernetes components and Tools for Kubernetes.

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