service-primitive

Service Primitive Example

This example demonstrates the usage of the service primitive within the operator component framework. It shows how to manage a Kubernetes Service as a component of a larger application, utilising features like:

• Base Construction: Initializing a Service with basic metadata, selector, and ports.
• Feature Mutations: Applying version-gated or conditional changes (additional ports, labels) using the Mutator.
• Field Flavors: Preserving annotations that might be managed by external tools (e.g., cloud load balancer controllers).
• Operational Status: Tracking whether the Service is operational (relevant for LoadBalancer types).
• Suspension: Demonstrating that, by default, the Service remains present when the component is suspended (DeleteOnSuspend=false), and how to opt into deletion if desired.
• Data Extraction: Harvesting information (ClusterIP, ports) from the reconciled resource.

Directory Structure

• app/: Defines the controller that uses the component framework. The ExampleApp CRD is shared from examples/shared/app.
• features/: Contains modular feature definitions:
  • mutations.go: version labelling and conditional metrics port.
• resources/: Contains the central NewServiceResource factory that assembles all features using service.Builder.
• main.go: A standalone entry point that demonstrates multiple reconciliation cycles with a fake client.

Running the Example

go run examples/service-primitive/main.go

This will:

1. Initialize a fake Kubernetes client.
2. Create an ExampleApp owner object.
3. Reconcile through four spec variations, printing the Service ports after each cycle.
4. Print the resulting status conditions.