This article summarizes the key topics covered in Kubernetes Workshop Series – 1, focusing on the fundamentals of Kubernetes and the problems it is designed to solve.
Monolithic vs Microservices Architecture
In a monolithic architecture, the entire application is built and deployed as a single unit. While this approach is simple at the beginning, it becomes difficult to scale, maintain, and update as the application grows.
Microservices architecture breaks an application into smaller, independent services. Each service can be developed, deployed, and scaled separately. This improves flexibility and scalability, but it also introduces operational complexity—this is where Kubernetes becomes important.
What is Kubernetes (K8s)?
Kubernetes (often abbreviated as K8s) is a container orchestration platform. It helps manage containerized applications by automating deployment, scaling, networking, and availability.
Problems Kubernetes Solves
- Managing large numbers of containers
- Automatic scaling of applications
- Self-healing (restarting failed containers)
- Service discovery and networking
- Configuration and secret management
Core Kubernetes Objects
Kubernetes works using a set of core objects:
Container
The smallest unit, usually a Docker container, that runs an application.Pod
A Pod is a wrapper around one or more containers. Containers in the same Pod share networking and storage.Node
A physical or virtual machine where Pods run.Cluster
A group of nodes managed together by Kubernetes.
Kubernetes Architecture
A Kubernetes cluster consists of a Control Plane (Master Node) and Worker Nodes.
Control Plane (Master Node)
The control plane manages the entire cluster:
API Server
The entry point for all Kubernetes commands and requests.Scheduler
Decides which node a Pod should run on.Controller Manager (c-m)
Ensures the desired state of the cluster (e.g., correct number of Pods running).etcd
A key-value store that holds all cluster configuration and state data.
Worker Node
Worker nodes run the actual workloads:
Container Runtime
Runs containers (e.g., Docker, containerd).kube-proxy
Handles networking and service communication.kubelet
Communicates with the control plane and ensures containers are running as expected.
Kubernetes Services
Services expose applications running in Pods:
ClusterIP
Exposes the service internally within the cluster.NodePort
Exposes the service on a static port on each node.LoadBalancer
Exposes the service using a cloud provider’s load balancer.ExternalName
Maps a service to an external DNS name.
Workload and Configuration Objects
ReplicaSet
Ensures a specified number of Pod replicas are running.Deployment
Manages ReplicaSets and provides features like rolling updates and rollbacks.ConfigMap
Stores non-sensitive configuration data.Secret
Stores sensitive data such as passwords, tokens, and keys.