example

Example: Testing function-auto-ready with Kubernetes Resources

This example demonstrates how the function-auto-ready composition function automatically detects readiness for standard Kubernetes resources using resource-specific health checks.

Files

• composition-k8s.yaml: A composition that creates three Kubernetes resources (Service, Deployment, ConfigMap) and uses function-auto-ready to detect their readiness
• xr.yaml: A simple composite resource (XR) instance to render the composition
• functions.yaml: Function definitions required by the Crossplane CLI
• observed-k8s.yaml: Simulated observed resources with status fields, used to test readiness detection with resources that already exist

What This Example Demonstrates

The composition creates three Kubernetes resources:

• Service (ClusterIP type) - Ready immediately since ClusterIP services don't require external provisioning
• Deployment (3 replicas, nginx) - Ready when all replicas are available and the Available condition is True
• ConfigMap - Ready immediately if it exists (no status conditions to check)

The function-auto-ready function automatically applies resource-specific health checks to determine when each resource is ready.

Testing Locally

Basic Rendering (Without Observed Resources)

To see what resources the composition creates:

crossplane render xr.yaml composition-k8s.yaml functions.yaml

This renders the desired state. Resources will not be marked as ready because they don't exist in the observed state yet.

Rendering with Observed Resources

To simulate resources that already exist in a cluster with their status fields populated:

crossplane render xr.yaml composition-k8s.yaml functions.yaml -o observed-k8s.yaml

This simulates the function behavior after Kubernetes has created the resources. The observed-k8s.yaml file contains:

• Service with empty status (ready immediately)
• Deployment with full status showing 3/3 replicas available and Available condition True (ready)
• ConfigMap with no status (ready immediately)

Expected Output

When rendered with observed resources, you should see:

• All three composed resources in the desired state
• Each resource marked with Ready: True in their annotations
• The composite resource (XR) marked as ready because all composed resources are ready

See Also

For a simpler example using Crossplane managed resources (AWS S3 Bucket), see the main README.md file in the repository root.