Understanding Kubernetes Architecture

Kubernetes is an open-source orchestration platform used to manage containers. This cloud-agnostic technology allows you to manage containerized applications across various cloud providers and over multiple hosts. 

It incorporates tools to streamline the management and deployment of containers, including horizontal scaling tools that automatically scale applications and a strong framework that ensures high availability. The platform also employs a resource metrics pipeline that lets the system self-manage resources to improve overall utilization.

Learn more about Kubernetes technology and how it can enhance your career opportunities.

What Is Kubernetes Architecture?

Kubernetes (k8s for short) is a distributed system with components that may be installed on virtual and bare metal servers. Originally developed by Google, it now falls under the Cloud Native Computing Foundation (CNCF), which provides support and direction for the project. Its basic element is a cluster that comprises one or more control plane nodes and one or more worker nodes, which can be physical servers or virtual machines, that run the container applications. They’re controlled by interacting with the Kubernetes API server, commonly using the command-line tool kubectl or various graphical user interfaces. These nodes include:

• Control plane. Previously known as master node, contains the core components to run Kubernetes and is installed on a host system. It controls worker nodes and pods and handles external communications and API requests to and from the user or the kubectl to the cluster. 
• Worker nodes. A Kubernetes cluster has at least one worker node containing a container runtime (like containerd or CRI-O; Docker Engine can also be used via components like cri-dockerd),  a kubelet agent that runs on the node, and kube-proxy, which manages network rules enabling communication to pods.The control plane’s scheduler assigns Pods to specific worker nodes; the kubelet on that node then ensures the containers defined in the Pod are started. These nodes can be distributed and are typically virtual machines or on-premise servers. 
• Pods. A pod is the smallest deployable Kubernetes unit and may include one or more containers with shared network and storage resources. A pod has a specific lifecycle and is bound to a specific worker node. They typically run single containers but may also run multiple tightly coupled containers that share resources. 
• Controllers and schedulers. The control plane includes controllers and schedulers that interact with the API server. Controllers watch the state of cluster objects via the API server and work to bring the actual state closer to the desired state.  These controllers manage the aspects of the cluster and include a ReplicaSet controller (often managed by deployments) that manages the number of replicas running and a node controller that determines whether nodes are ready. The scheduler watches for newly created pods without an assigned node and selects a suitable worker node for them based on resource requirements, constraints, and other policies

Key Components of Kubernetes Architecture

To understand how Kubernetes clusters work, it’s helpful to take a detailed look at some essential elements of the Kubernetes architecture:

• API server. Acting as the central hub of the cluster, it processes all API requests and coordinates processes between the control plane and worker nodes.  The server validates instructions and configures data for objects, including the worker node and pods. You can use the API server to query and control the state of objects within the cluster. 
• etcd. A distributed key-value store located over multiple control-plane nodes. This store is configured as a strongly consistent key-value store, which means any changes in the configuration or state of one storage node are immediately written to all other nodes in the cluster. Its distributed nature using a consensus algorithm (like Raft) allows the etcd cluster to tolerate the failure of some of its members (typically running on control plane nodes) while maintaining data consistency and availability for the Kubernetes API
• Kubelet. This program runs as a background process on worker nodes. The kubelet registers worker nodes with the API server and receives Pod specifications. (PodSpecs) from the API server and ensures the containers described in those PodSpecs are running and healthy.
• Kube-proxy. Kube-proxy maintains network rules on nodes. These rules enable network communication to Pods, primarily by implementing the Kubernetes Service concept, directing traffic destined for a Service IP/port to the correct backend Pods.
• Container runtime. A container runtime is installed on each worker node in the cluster and provides the infrastructure that allows containers to run. Kubernetes supports various runtimes conforming to its Container Runtime Interface (CRI), including containerd, CRI-O, and others. While direct integration with Docker Engine was removed, it can still be used via adapters like cri-dockerd. The container runtime service takes container images from the container registries, runs them in the appropriate pod, and manages the lifecycle of each container. 

How Kubernetes Manages Applications

One of the strengths of Kubernetes is how it automatically manages distributed container workloads. It does this through components like the kube-scheduler, which is part of the control plane. Key tools for managing applications include:

• Load balancing and service discovery. Kubernetes uses Services to provide reliable endpoints and load balancing across a set of Pods within the cluster. For managing external access to these Services (typically HTTP/S traffic), Kubernetes uses Ingress resources. 
• Storage orchestration. Kubernetes can create storage volumes on demand using dynamic volume configuration. The default storage configuration in pods and containers is temporary or nonpersistent, using ephemeral storage volumes that only exist while the container is active. Containers can also use persistent storage for applications that need ongoing access to read and write data.
• Automated rollouts and rollbacks. Kubernetes lets you deploy new versions of a container image without interrupting production. Deployment is done by creating a ReplicaSet and new pods with the latest software version. At the same time, it stops pods in the original ReplicaSet. If you encounter an unforeseen problem, you can roll back to the configuration defined by the previous ReplicaSet.
• Self-healing. Kubernetes can implement self-healing to address container failures. It uses liveness and readiness probes to determine pod and container status, such as whether a pod is pending, running, succeeded, failed, or of unknown status. If a container fails or is unresponsive, Kubernetes attempts to restart it. Furthermore, if a whole Pod disappears (e.g., due to node failure), controllers managing that Pod (like Deployments or StatefulSets) will detect its absence and schedule a replacement Pod on an available node.

Careers That Use Kubernetes

Kubernetes is one of the most popular container orchestration platforms on the market. According to the 2023 CNCF annual web survey, 66% of consumers were using Kubernetes in production, while a further 18% were evaluating it. The most common architectures used were public, private, and hybrid clouds. Some prominent careers where Kubernetes skills are considered essential include:  

• DevOps engineers. DevOps engineers are responsible for the smooth functioning of an organization’s IT infrastructure. They need a good understanding of using Kubernetes in continuous integration and development (CI/CD) pipelines and should be familiar with deploying Kubernetes across multiple platforms. 
• Cloud engineers. A cloud engineer plays a vital role in implementing public, private, and hybrid clouds. Kubernetes is the predominant platform for distributed computing across clouds. Besides the open-source version, major cloud providers offer managed Kubernetes services, including Azure Kubernetes, Google Kubernetes Engine, and Amazon EKS. 
• Site reliability engineers. An SRE is responsible for ensuring all IT systems perform optimally. Containerized applications need to scale quickly and efficiently to respond to high demand and rollback when demand is low. Kubernetes is the most commonly used distributed platform for running containers.
• Software developers. Responsible for writing and testing software, software developers prefer Kubernetes for its ability to simplify orchestration of microservices using containers. Thanks to its portability, developers can write software using in-house resources and test and transport them into production across different clouds. It helps them develop complex applications through its automated provisioning, scaling, and management capabilities.
• IT administrators. An IT administrator is responsible for an organization’s IT network. They implement security protocols, access control, and create user accounts. The administrator must have a detailed working knowledge of all systems and solutions employed by the organization. Holding a Kubernetes Administrator certification (like the CKA) can also be highly beneficial for this role.

Why Leaning Kubernetes Can Boost Your Career

The demand for Kubernetes is growing thanks to its unique ability to orchestrate containers across different architectures. It simplifies building applications at scale, and its strengths include automation, autoscaling, monitoring, and high availability. Industries adopting Kubernetes include:

• Financial services. Popular for high availability, scalable, mission-critical financial services 
• Healthcare. Used for telemedicine and health record systems
• E-commerce. The development of scalable online platforms that can securely handle high transaction volumes
• Media. Good for low latency streaming and content delivery services

Engineers with Kubernetes experience are in high demand, and there’s a shortage of suitably qualified and certified experts. Kubernetes-qualified engineers have potential career opportunities among companies of all sizes, including start-ups, small, medium, and large enterprises, and cloud providers, such as AWS, Google, and Azure. 

How to Learn Kubernetes on Udemy

At Udemy, you’ll find an extensive selection of Kubernetes courses and projects, ranging from free introductory courses to advanced certification training. Our courses are available on demand, so you can enroll anytime and work at your own pace. 

Udemy courses for mastering Kubernetes include:

• Free introductory courses. These free Kubernetes courses provide a simple introduction to help you get started. 
• Beginner courses. Udemy’s beginner Kubernetes courses are an easy and fun way to develop an understanding of the fundamentals and architecture. These courses include several hours of on-demand video training, downloadable resources, and multiple coding exercises. 
• Advanced training. Advanced Kubernetes courses are ideal once you’ve developed an appreciation of the technology. These courses teach how to deploy Kubernetes, automate projects, and implement security to keep your projects safe. The complete Kubernetes DevOps course demonstrates how to run and manage containerized applications and includes 14.5 hours of video, two practice tests, and a certificate of completion.  
• Hands-on Labs. We offer a selection of hands-on Kubernetes projects that let you create real-world projects. These projects help hone your skills and teach you how to translate your technical knowledge into practical applications. 

Kubernetes Certifications

Udemy offers a range of courses with practice exams that prepare you for the Cloud Native Computing Foundation (CNCF) certification examinations. These certifications showcase your ability to design and build cloud-native Kubernetes applications. Udemy certification preparation courses include: 

• Certified Kubernetes Administrator
• Certified Kubernetes Application Developer
• Certified Kubernetes Security Specialist

Become A Kubernetes Expert

Kubernetes is the foremost open-source containerization platform that works on all public and private clouds, and it excels at managing large-scale containerization with multiple modes. Obtaining qualifications in this technology can open up exciting career opportunities across various industries.Explore Udemy’s broad selection of Kubernetes courses and choose one that matches your experience and knowledge. Start your Kubernetes career by signing up today.