🔧 Kubernetes Extensions

CRDs & Custom Resources

Learn how to extend the Kubernetes API with Custom Resource Definitions. Master the art of creating domain-specific resources for your applications.

Prerequisites

What You Should Know Before Starting

Essential knowledge for working with CRDs and Custom Resources

  • Understanding of Kubernetes API concepts
  • Basic knowledge of YAML and JSON
  • Experience with kubectl commands
  • Familiarity with Kubernetes resources

Learning Topics

CRD Fundamentals

2-3 hours

Understanding Custom Resource Definitions and their structure

Learning Objectives:

  • •CRD Schema Definition
  • •API Versioning
  • •Validation Rules
  • •Default Values
  • •Status Subresources

Custom Resources

2-3 hours

Creating and managing custom resources in Kubernetes

Learning Objectives:

  • •Resource Lifecycle
  • •CRUD Operations
  • •Resource Validation
  • •Status Management
  • •Finalizers

API Extensions

3-4 hours

Extending the Kubernetes API with custom resources

Learning Objectives:

  • •API Server Integration
  • •Aggregated APIs
  • •API Discovery
  • •OpenAPI Schema
  • •Client Libraries

Advanced CRD Patterns

2-3 hours

Advanced patterns and best practices for CRDs

Learning Objectives:

  • •Conversion Webhooks
  • •Admission Controllers
  • •Schema Evolution
  • •Migration Strategies
  • •Performance Optimization

Key Concepts

CRD Schema

Defining the structure and validation rules for custom resources.

  • • OpenAPI schema definition
  • • Field validation rules
  • • Required and optional fields
  • • Default value specifications

Custom Resources

Instances of custom resources that follow the CRD schema.

  • • Resource lifecycle management
  • • CRUD operations
  • • Status and spec sections
  • • Finalizers and cleanup

API Integration

Integrating custom resources with the Kubernetes API.

  • • API server registration
  • • Discovery and versioning
  • • Client library generation
  • • RBAC and permissions

Advanced Features

Advanced CRD features for complex use cases.

  • • Conversion webhooks
  • • Admission controllers
  • • Schema evolution
  • • Performance optimization

CRD Development Workflow

1. Design

Design the schema and API structure for your custom resource.

Schema Design

2. Define

Create the CRD YAML definition with validation rules.

CRD YAML

3. Deploy

Deploy the CRD to your Kubernetes cluster.

kubectl apply

4. Use

Create and manage custom resource instances.

Custom Resources

Ready to Continue?

Master CRDs and Custom Resources, then learn about Operator concepts and patterns.

Next: Operator ConceptsBack to Operators Overview