Kubernetes Operator Patterns

1. Introduction

Kubernetes Operators are a method of packaging, deploying, and managing a Kubernetes application. They extend Kubernetes' capabilities to manage complex stateful applications by using the Kubernetes API and tooling.

2. Key Concepts

• CRD (Custom Resource Definition): Defines a new resource type in the Kubernetes API.
• Controller: Watches the state of a resource and makes or requests a change where needed.
• Custom Resources: Instances of CRDs; they represent the desired state of the application.

3. Operator Patterns

Operator patterns refer to the various design and implementation strategies for building operators. Some common patterns include:

1. Deployment Operator: Manages the lifecycle of an application, ensuring the desired state is maintained.
2. Backup and Restore Operator: Manages backup schedules and restores data as needed.
3. Scaling Operator: Automatically scales applications based on metrics such as CPU and memory usage.
4. Curator Operator: Manages the lifecycle of a collection of resources, ensuring they are configured and running correctly.

Each of these patterns can be implemented using controllers that watch for changes in their respective resources.

4. Best Practices

• Use well-defined CRDs to represent your application's desired state.
• Implement health checks to monitor the state of your application.
• Document your operator’s behavior to ensure ease of use.
• Test your operator thoroughly before deploying to production.
• Follow Kubernetes conventions for naming, labels, and annotations.

5. FAQ