• Understanding Kubernetes Architecture and Its Use Cases
• Deploying ASP.NET Core App Using Kubernetes
• Managing Secrets in Kubernetes
• Data Persistence with Volume Mounting in Kubernetes

Understanding Kubernetes Architecture and Its Use Cases

Kubernetes has become the gold standard for container orchestration and management. Its robust ecosystem and powerful features make it the top choice for deploying, scaling, and managing containerized applications. In this advanced blog post, we’ll explore Kubernetes in-depth, covering its architecture, core components, and advanced concepts. To enhance your understanding, we’ll provide YAML examples and a real-world use case.

Section 1: Understanding Kubernetes Architecture

Kubernetes architecture is designed to deliver scalability, high availability, and resilience for containerized applications. Let’s delve into its core components:

1.1 Master Node

The Master Node, also known as the Control Plane, manages the entire Kubernetes cluster. It comprises several critical components:

• API Server: Serves as the entry point for administrative tasks and provides a REST API for communication with other components.

• etcd: A distributed key-value store that houses all cluster data, including configuration settings, state, and metadata.

• Controller Manager: Monitors the cluster’s state through the API Server and ensures that the desired state is maintained.

• Scheduler: Assigns workloads to nodes based on resource availability and constraints.

1.2 Node (Minion)

Nodes, also referred to as Minions, are the worker machines responsible for executing containerized applications. Key components of a Node include:

• Kubelet: Ensures that containers run inside a Pod. It communicates with the Master Node and manages container lifecycles.

• Container Runtime: The software responsible for running containers (e.g., Docker or containerd).

• Kube Proxy: Maintains network rules on the host and facilitates communication between Pods on different nodes.

Section 2: Kubernetes Objects

Kubernetes manages applications using objects like Pods, Services, and Deployments. These objects are defined using YAML or JSON and stored in etcd. Below, we’ll cover some essential Kubernetes objects:

2.1 Pods

In a YAML file, a Pod definition might look like this:

apiVersion: v1
kind: Pod
metadata:
  name: example-pod
spec:
  containers:
    - name: container-1
      image: nginx:latest
    - name: container-2
      image: busybox:latest

Real-World Use Case: Suppose you’re running a web application comprising a front-end (HTML/CSS/JavaScript) served by Nginx (container-1) and a lightweight backend API (container-2) using BusyBox. Deploying both containers in a single Pod ensures they share the same network namespace.

2.2 Services

In a YAML file, a Service definition might look like this:

apiVersion: v1
kind: Service
metadata:
  name: example-service
spec:
  selector:
    app: example-app
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080

Real-World Use Case: Imagine you have a set of Pods (Pod_1 and Pod_2) running a microservices architecture, and you want to expose them as a single entry point for external users. By creating a Service, you provide load balancing and a stable IP address for accessing your Pods, regardless of the number of replicas or their nodes.

2.3 Deployments

In a YAML file, a Deployment definition might look like this:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: example-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: example-app
  template:
    metadata:
      labels:
        app: example-app
    spec:
      containers:
        - name: example-container
          image: nginx:latest

Real-World Use Case: You’re running a web application with multiple Pods, and you want to ensure that three replicas are always running. The Deployment handles rolling updates and maintains the desired number of replicas for high availability, even in the event of failures or updates.

The flow of services and deployments is shown in the diagram below.