Kubernetes Architecture

Kubernetes Architecture

Components

1. API Server (kube-apiserver): Handles requests and updates.

2. Scheduler (kube-scheduler): Assigns pods to nodes.

3. Controller Manager (kube-controller-manager): Runs controllers.

4. etcd: Distributed key-value store for cluster state.

5. Worker Nodes (kubelet): Run pods.

Architecture Diagram

Cluster → Nodes → Pods → Containers

Key Concepts

1. Cluster: Group of nodes.

2. Node: Physical or virtual machine.

3. Pod: Basic execution unit (one or more containers).

4. Container: Lightweight and portable.

5. Control Plane: Manages cluster.

Design Principles

1. Declarative Configuration: Define desired state.

2. Immutable Infrastructure: No in-place updates.

3. Self-healing: Automatic restart and recovery.

Benefits

1. Scalability

2. High Availability

3. Flexibility

4. Security

5. Efficiency

Evolution

1. Kubernetes 1.x: Initial releases.

2. Kubernetes 1.8+: Production-ready features.

3. Kubernetes 1.16+: Enhanced security. Future Developments

Here are the key Kubernetes components:

Control Plane Components

1. API Server (kube-apiserver): Handles requests and updates.

2. Scheduler (kube-scheduler): Assigns pods to nodes.

3. Controller Manager (kube-controller-manager): Runs controllers.

4. etcd: Distributed key-value store for cluster state.

Worker Node Components

1. Kubelet: Runs pods and communicates with API Server.

2. Proxy (kube-proxy): Handles network traffic.

Networking Components

1. Pod Network: Enables pod-to-pod communication.

2. Service Network: Enables service-to-service communication.

Storage Components

1. Persistent Volumes (PVs): Provisioned storage.

2. Persistent Volume Claims (PVCs): Requests for storage.

Security Components

1. Authentication: Verifies user identity.

2. Authorization: Controls access to resources.

3. Network Policies: Controls network traffic.

Add-ons

1. Dashboard: Web-based UI.

2. Monitoring (Prometheus, Grafana): Tracks performance.

3. Logging (Fluentd, Elasticsearch): Collects logs.

Other Components

1. Ingress Controller: Manages incoming traffic.

2. Service Load Balancer: Distributes traffic. 3

. Federation: Multi-cluster management.

Here are the advantages and use cases of Kubernetes:

Advantages:

1. Scalability: Automatic scaling of applications.

2. High Availability: Self-healing and automatic restart.

3. Flexibility: Supports multiple container runtimes.

4. Security: Network policies and secret management.

5. Efficiency: Resource optimization and utilization.

6. Portability: Runs on any infrastructure.

7. Automation: Streamlines deployment and management.

8. Monitoring: Integrated logging and monitoring.

9. Collaboration: Multi-user and multi-tenant support.

10. Extensibility: Large ecosystem of plugins and integrations.

Use Cases:

1. Web Applications

- Scalable web servers

- Load balancing and ingress

- Microservices architecture

2. Microservices Architecture

- Service discovery and communication

- API gateways and proxies

- Distributed transaction management

3. Big Data and Analytics

4. Machine Learning and AI

5. Cloud-Native Applications

- Serverless computing

- Function-as-a-Service (FaaS)

- Event-driven architecture

6. DevOps and Continuous Integration

- Automated testing and deployment

- Continuous delivery and monitoring

- Infrastructure-as-Code (IaC)

7. Hybrid and Multi-Cloud

- Multi-cloud deployment and management

- Cloud-agnostic infrastructure

- Disaster recovery and business continuity

8. IoT and Edge Computing Here's an overview of Pods and Containers in Kubernetes: Pods - Basic execution unit in Kubernetes - Logical host for one or more containers - Shared resources (network, storage) - Shared lifecycle (created, running, terminated) Pod Characteristics 1. One or more containers 2. Shared network namespace (IP, ports) 3. Shared storage (volumes) 4. Shared lifecycle 5. Dynamic scaling and replication Container - Lightweight and portable application package - Runs in a Pod - Isolated from other containers Container Characteristics 1. Lightweight (MBs, not GBs) 2. Portable (runs on any platform) 3. Isolated (own process, network, filesystem) 4. Immutable (no changes after creation) Pod-Container Relationship 1. One or more containers per Pod 2. Containers share Pod resources 3. Pod lifecycle manages container lifecycle Types of Pods 1. Single-container Pod 2. Multi-container Pod 3. Init Container 4. Sidecar Container Types of Containers 1. Application Container 2. Init Container 3. Sidecar Container 4. Daemon Container Container Runtimes 1. Docker 2. rkt 3. CRI-O 4. containerd Pod Management 1. Create/Update/Delete Pods 2. Scaling (ReplicaSets, Deployments) 3. Self-healing (automatic restart) 4. Networking (Pod-to-Pod, Pod-to-Service) Container Management 1. Create/Update/Delete Containers 2. Resource allocation (CPU, memory) 3. Networking (container-to-container) 4. Logging and monitoring 1. Serverless Computing 2. Service Mesh 3. Cloud-Native Storage 4. Artificial Intelligence (AI) Integration