What is Kubernetes? Complete Guide

You’ve probably seen apps like Spotify or Netflix handling millions of users seamlessly, without crashing or slowing down? But do you what makes it possible? The answer often lies in Kubernetes. But What is Kubernetes, and why is it becoming essential for businesses worldwide? This platform supports automating the deployment, scaling, and management of your containerised applications. 

In this blog, we'll dive into what Kubernetes is, how it works, and why mastering it can dramatically simplify your workflow. Want to revolutionise your app development? Let's read ahead!

Table of Contents 

1) What is Kubernetes?

2) How Does Kubernetes Work?

3) Key Concepts of Kubernetes

4) Architecture of Kubernetes

5) Advantages and Disadvantages of Kubernetes

6) Kubernetes vs Docker

7) How to Install Kubernetes?

8) Conclusion

What is Kubernetes? 

Kubernetes, also known as K8s, is an open-source Container Orchestration platform that has gained significant popularity in modern application deployment. With its ability to automate and manage containerised applications, Kubernetes offers a solution for scaling, managing, and deploying applications across various environments. As highlighted in the Kubernetes Guide, it provides a framework that containerises applications, enabling developers to abstract away the infrastructure and focus on building and scaling their applications seamlessly. Kubernetes makes things easier by handling the following jobs:

a) Arranging containers

b) Adjusting their numbers

c) Balancing the work

d) Fixing problems

These makes it easier to deal with complicated application setups. Instead of worrying about every single container, Kubernetes gives  one place to oversee the whole application.

    

How Does Kubernetes Work?

1) Planning Your Application

a) Developers build applications using multiple containers.

b) They clearly define how each container interacts, how many containers are needed, and what to do during unexpected events like sudden spikes in user traffic.

2) Storing Containers and Configurations

a) Containers are safely stored in a container registry, either locally or online.

b) Developers document instructions for deploying the application using configuration files, typically written in Yet Another Markup Language (YAML) format.

3) Deploying Applications via Kubernetes

a) Developers submit (or "apply") their configuration files to Kubernetes.

b) Kubernetes reads these instructions and deploys the containers as specified.

4) Analysing Requirements and Allocating Resources

a) Kubernetes reviews configuration files to fully understand the application’s requirements.

b) It smartly allocates containers across available computing resources for optimal performance.

5) Continuous Monitoring and Self-healing

a) Kubernetes constantly monitors the health and performance of the application.

b) If a container crashes or encounters an issue, Kubernetes automatically restarts it, keeping disruptions to a minimum.

6) Automatic Failover

Should a server running containers fail, Kubernetes quickly relocates the affected containers to another healthy server, maintaining application stability.

7) Automatic Scaling

a) Kubernetes detects increased user demand and automatically adds containers to handle higher traffic.

Scaling occurs based on predefined guidelines, ensuring consistent and smooth application performance; even under heavy load.

Key Concepts of Kubernetes

Kubernetes is built on a set of key concepts that form the foundation of its functionality. Understanding these concepts is essential for effectively working with Kubernetes and harnessing its full potential. Let's explore these key concepts in detail:
 

Master Nodes

Master nodes serve as the control center of a Kubernetes cluster, overseeing workload management, scaling, and communication. They coordinate cluster operations through core components such as the Application Programming Interface (API) Server, Scheduler, Controller Manager, and etc for storing cluster state. Master nodes ensure efficient workload distribution and high availability.

Worker Nodes

Worker nodes are responsible for executing application workloads by running containers within pods. Each node includes a Kubelet to communicate with the master node, a container runtime (like Docker) to run containers, and a Kube-proxy for networking. They manage the execution of scheduled tasks and ensure smooth operation of applications.

Pods

Pods are the smallest deployable units in Kubernetes, consisting of one or more containers that share resources like storage and networking. They ensure containers operate together as a unit and simplify scaling. Each pod has a unique Internet Protocol (IP) address and can be replaced or replicated as needed to maintain high availability.

Services

Services provide a stable network endpoint for pods, ensuring continuous communication despite pod restarts or changes in IP addresses. They function as load balancers, efficiently distributing traffic between pods and enabling seamless interaction between different application components within a Kubernetes cluster.

Deployments

Deployments automate the management of pods, handling tasks such as scaling, updates, and rollbacks. They define how applications should be deployed and maintained, ensuring minimal downtime during updates. By managing replicas, deployments enhance application availability, allowing for seamless upgrades and rollback mechanisms.

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Architecture of Kubernetes 

Kubernetes architecture is divided into two main components: Control Plane Components, which manage and orchestrate the cluster, and Node Components, which execute workloads. The control plane ensures cluster stability, while nodes efficiently run applications.

1) Control Plane Components 

The following are the key control plane components: 

a) API Server

The API Server acts as the core communication gateway of Kubernetes, handling all requests from users and internal components via REST API. It validates and processes commands, ensuring the desired state of the cluster is maintained. It also interacts with etcd to store and retrieve cluster data.

b) etcd

etcd is a distributed, highly available key-value store that holds all cluster configurations and states. It ensures consistency across the cluster by storing information about nodes, pods, and deployments. In case of a failure, etcd helps restore the cluster’s last known state.

c) Scheduler

The Scheduler is responsible for assigning newly created pods to available worker nodes based on resource availability, constraints, and workload balance. It ensures optimal resource utilisation by considering Central Processing Unit (CPU), memory, and other parameters before making placement decisions.

d) Controller Manager

The Controller Manager runs various controllers that regulate cluster operations. It oversees processes like node health checks, replication of pods, and auto-scaling. It ensures the cluster maintains the desired state by reconciling differences between the current and expected conditions.

2) Node Components 

The following are the key Node components: 

a) Kubelet

Kubelet is an agent that runs on every worker node, ensuring that containers within pods are running as expected. It continuously communicates with the API Server, retrieves pod definitions, and monitors their health, restarting containers if they fail.

b) Container Runtime

The container runtime, such as Docker, or Container Runtime Interface for OpenShift (CRI-O), is responsible for executing and managing containers on a node. It isolates applications, handles networking, and ensures seamless deployment of workloads across the Kubernetes cluster.

c) kube-proxy

Kube-proxy manages network traffic between nodes and pods by maintaining network rules and load balancing services. It enables seamless communication between pods and ensures stable connectivity across the cluster by handling forwarding requests.

d) Networking

Kubernetes networking provides seamless communication between pods, services, and external users. Each pod receives a unique IP, and network policies define how they communicate within the cluster. It ensures efficient service discovery, load balancing, and security across deployments.

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Advantages and Disadvantages of Kubernetes

Kubernetes is a popular choice for container orchestration due to its automation, scalability, and flexibility. However, it also presents challenges such as complexity and resource overhead. Below are the key advantages and disadvantages of Kubernetes

 

Advantages of Kubernetes 

The following are the advantages of Kubernetes: 

a) Scalability and High Availability

Kubernetes automatically scales applications based on workload demand, ensuring consistent performance. It distributes workloads across multiple nodes, preventing failures and reducing downtime. High availability mechanisms, such as pod replication and self-healing, keep applications running smoothly.

b) Automation and Orchestration

The built-in automation in Kubernetes reduces manual intervention in deploying and managing applications. It automatically schedules containers, handles failures, restarts unhealthy pods, and optimises resource allocation, making application management more efficient and reliable.

c) Portability and Flexibility

Kubernetes is cloud-agnostic, allowing applications to run across different cloud providers or on-premises infrastructure. It supports various container runtimes and configurations, making it a highly flexible solution for organisations using multi-cloud or hybrid cloud environments.

d) Service Discovery and Load Balancing

Kubernetes automatically assigns a stable network identity to services, simplifying service discovery. It also balances traffic across available pods, preventing overload on a single container. This ensures applications remain responsive and efficient under varying workloads.

e) Rolling Updates and Rollbacks

With rolling updates, Kubernetes allows seamless deployment of new application versions without downtime. If an update causes issues, rollbacks can be triggered instantly to restore the previous stable version. This minimises risks during software updates and ensures system reliability.

Disadvantages of Kubernetes

The following are some of the main disadvantages of Kubernetes:  

a) Complexity

Kubernetes has a steep learning curve and requires expertise in containerisation, networking, and security. Setting up clusters, managing configurations, and troubleshooting issues demand specialised knowledge, making adoption challenging for beginners.

b) Operational Overhead

Despite automation, Kubernetes requires continuous monitoring and management. Teams must handle updates, security patches, and cluster scaling, leading to increased operational costs. Proper resource allocation and optimisation are necessary to avoid inefficiencies.

c) Resource Consumption

Kubernetes consumes significant system resources due to its control plane and node components. Running a Kubernetes cluster requires substantial CPU, memory, and storage, increasing infrastructure costs, especially for small-scale applications.

d) The Complexity of Networking

Kubernetes networking involves multiple layers, including pod communication, service discovery, and ingress controllers. Configuring networking policies, securing traffic, and ensuring smooth inter-service communication can be complex, requiring detailed planning.

e) Security Considerations

Kubernetes provides security mechanisms, but misconfigurations can introduce vulnerabilities. Managing role-based access (RBAC), securing secrets, and implementing proper authentication policies are essential to prevent unauthorised access and cyber threats.

Kubernetes vs Docker

Kubernetes and Docker are actually different, but they work well together. They help developers in running containerised applications. 

Docker allows developers to put the things, they require into a box which can be stored and accessed whenever it is required. But when developers have lots of these toolboxes, they need a tool to organise and control them, and that's what Kubernetes does. Here are some of the differences:

a) Kubernetes can work with or without Docker

b) The difference between Docker and Kubernetes connects to the role they play in containerising and running your applications.

c) Kubernetes uses Docker to deploy, handle, and expand applications stored in containers

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How to Install Kubernetes?

Lets take a look at How to Install Kubernetes on Ubuntu:

a) Open the terminal on Ubuntu.

b) Install the essential dependencies by writing the following code:
 

c) Then, install the Docker Dependency using:
 

d) Enable Docker with the commands given below:
 

e) Next step is to install the essential components for Kubernetes such as installing curl command using:
 

 

f) After installing curl, add they key for the Kubernetes to install:
 

 

g) You can change the permission using:
 

 

h) After doing the above steps, add a repository by creating the file /etc/apt/sources.list.d/kubernetes.list and enter the following content: deb http://apt.kubernetes.io/ kubernetes-xenial main
 

i) You can now save and close that file. 

j) Install Kubernetes using the following command:
 

You have successfully installed Kubernetes in your system.

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What is Kubernetes Used For?

Kubernetes is mainly used to automate how containerised apps are deployed, scaled, and managed. It ensures applications run smoothly, remain resilient, and scale easily across different environments, speeding up your development process.

Can I Learn Kubernetes Without Docker?

Yes, you can learn Kubernetes without Docker, but understanding container basics first makes it much simpler. Docker provides an easy introduction to containers, helping you grasp Kubernetes concepts faster.

Conclusion 

So, what is Kubernetes? To put it simply, it's your go-to solution for managing apps smoothly and reliably. With Kubernetes, scaling up, handling failures, and responding quickly becomes effortless. Want to simplify your workflow and boost productivity? Kubernetes has your back! 

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