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Merge pull request #160 from kaessert/tk/v2-standard-kube-resources
Add resource-specific health checks for standard Kubernetes resources
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‎README.md‎

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@@ -6,11 +6,67 @@ resources that are ready. It considers a composed resource ready if:
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* Another function added the composed resource to the desired state.
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* The composed resource appears in the observed state (i.e. it exists).
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* The composed resource has the status condition `type: Ready`, `status: True`.
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* **For standard Kubernetes resources** with health check implementations (see list below), the resource passes resource-specific health checks.
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* **For all other resources** (Crossplane managed resources, custom resources, etc.), the composed resource has the status condition `type: Ready`, `status: True`.
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Crossplane considers a composite resource (XR) to be ready when all of its
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desired composed resources are ready.
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## Health Checks
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This function implements resource-specific health checks for standard Kubernetes resources. The following table shows the current implementation status:
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### Core (core/v1)
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- [x] Pod - Succeeded, or Running with Ready condition (RestartPolicy: Always)
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- [x] Service - ClusterIP/NodePort: immediately ready; LoadBalancer: requires ingress assignment
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- [x] Namespace - Always ready if it exists
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- [ ] Node
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- [x] ConfigMap - Always ready if it exists
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- [x] Secret - Always ready if it exists
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- [x] ServiceAccount - Always ready if it exists
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- [ ] Endpoints
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- [ ] PersistentVolume
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- [x] PersistentVolumeClaim - Phase is Bound
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- [ ] ReplicationController
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- [ ] ResourceQuota
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- [ ] LimitRange
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- [ ] Event
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### Apps (apps/v1)
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- [x] Deployment - `spec.replicas == status.availableReplicas`, all replicas updated, `Available` condition is `True`
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- [x] StatefulSet - `spec.replicas == status.readyReplicas`, all replicas at current revision
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- [x] DaemonSet - All desired pods are scheduled, ready, updated, and available
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- [x] ReplicaSet - Observed generation matches, available replicas match desired, no replica failures
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### Batch (batch/v1)
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- [x] Job - Complete condition is True (not Failed or Suspended)
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- [x] CronJob - Suspended, has active jobs, or last execution succeeded
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### Autoscaling (autoscaling/v2)
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- [x] HorizontalPodAutoscaler - ScalingActive or ScalingLimited, no failed conditions
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### Networking (networking.k8s.io/v1)
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- [x] Ingress - Load balancer ingress is assigned
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- [ ] IngressClass
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- [ ] NetworkPolicy
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### RBAC (rbac.authorization.k8s.io/v1)
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- [ ] Role
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- [ ] ClusterRole
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- [ ] RoleBinding
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- [ ] ClusterRoleBinding
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### Storage (storage.k8s.io/v1)
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- [ ] StorageClass
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- [ ] VolumeAttachment
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- [ ] CSIDriver
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- [ ] CSINode
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### Policy (policy/v1)
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- [ ] PodDisruptionBudget
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For all other resource types (Crossplane managed resources, custom resources, etc.), the function falls back to checking the standard Ready status condition.
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In this example, the [Go Templating][fn-go-templating] function is used to add
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a desired composed resource - an Amazon Web Services S3 Bucket. Once Crossplane
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has created the Bucket, the Auto Ready function will let Crossplane know when it
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the Crossplane CLI:
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```shell
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$ crossplane beta render xr.yaml composition.yaml functions.yaml
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$ crossplane render xr.yaml composition.yaml functions.yaml
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```
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To test with observed resources (simulating resources that already exist):
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```shell
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$ crossplane render xr.yaml composition-k8s.yaml functions.yaml -o observed-k8s.yaml
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```
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See the [composition functions documentation][docs-functions] to learn more
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about `crossplane beta render`.
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about `crossplane render`.
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## Developing this function
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‎example/README.md‎

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# Example: Testing function-auto-ready with Kubernetes Resources
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This example demonstrates how the function-auto-ready composition function automatically detects readiness for standard Kubernetes resources using resource-specific health checks.
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## Files
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- **composition-k8s.yaml**: A composition that creates three Kubernetes resources (Service, Deployment, ConfigMap) and uses function-auto-ready to detect their readiness
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- **xr.yaml**: A simple composite resource (XR) instance to render the composition
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- **functions.yaml**: Function definitions required by the Crossplane CLI
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- **observed-k8s.yaml**: Simulated observed resources with status fields, used to test readiness detection with resources that already exist
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## What This Example Demonstrates
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The composition creates three Kubernetes resources:
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- **Service** (ClusterIP type) - Ready immediately since ClusterIP services don't require external provisioning
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- **Deployment** (3 replicas, nginx) - Ready when all replicas are available and the Available condition is True
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- **ConfigMap** - Ready immediately if it exists (no status conditions to check)
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The function-auto-ready function automatically applies resource-specific health checks to determine when each resource is ready.
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## Testing Locally
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### Basic Rendering (Without Observed Resources)
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To see what resources the composition creates:
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```shell
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crossplane render xr.yaml composition-k8s.yaml functions.yaml
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```
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This renders the desired state. Resources will not be marked as ready because they don't exist in the observed state yet.
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### Rendering with Observed Resources
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To simulate resources that already exist in a cluster with their status fields populated:
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```shell
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crossplane render xr.yaml composition-k8s.yaml functions.yaml -o observed-k8s.yaml
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```
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This simulates the function behavior after Kubernetes has created the resources. The observed-k8s.yaml file contains:
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- Service with empty status (ready immediately)
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- Deployment with full status showing 3/3 replicas available and Available condition True (ready)
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- ConfigMap with no status (ready immediately)
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### Expected Output
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When rendered with observed resources, you should see:
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- All three composed resources in the desired state
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- Each resource marked with `Ready: True` in their annotations
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- The composite resource (XR) marked as ready because all composed resources are ready
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## See Also
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For a simpler example using Crossplane managed resources (AWS S3 Bucket), see the main README.md file in the repository root.

‎example/composition-k8s.yaml‎

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apiVersion: apiextensions.crossplane.io/v1
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kind: Composition
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metadata:
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name: example-k8s-resources
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spec:
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compositeTypeRef:
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apiVersion: example.crossplane.io/v1
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kind: XR
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mode: Pipeline
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pipeline:
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- step: create-k8s-resources
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functionRef:
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name: function-go-templating
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input:
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apiVersion: gotemplating.fn.crossplane.io/v1beta1
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kind: GoTemplate
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source: Inline
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inline:
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template: |
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---
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apiVersion: v1
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kind: Service
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metadata:
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name: example-service
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annotations:
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gotemplating.fn.crossplane.io/composition-resource-name: service
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spec:
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type: ClusterIP
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selector:
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app: example
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ports:
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- port: 80
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targetPort: 8080
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---
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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name: example-deployment
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annotations:
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gotemplating.fn.crossplane.io/composition-resource-name: deployment
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spec:
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replicas: 3
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selector:
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matchLabels:
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app: example
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template:
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metadata:
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labels:
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app: example
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spec:
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containers:
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- name: app
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image: nginx:latest
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ports:
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- containerPort: 8080
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---
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apiVersion: v1
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kind: ConfigMap
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metadata:
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name: example-config
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annotations:
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gotemplating.fn.crossplane.io/composition-resource-name: config
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data:
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config.yaml: |
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key: value
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# This function will automatically detect readiness using resource-specific health checks
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- step: automatically-detect-ready-composed-resources
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functionRef:
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name: function-auto-ready

‎example/observed-k8s.yaml‎

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# This file simulates observed resources as they would appear in a running cluster
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# Use this with: crossplane render xr.yaml composition-k8s.yaml functions.yaml -o observed-k8s.yaml
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---
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apiVersion: v1
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kind: Service
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metadata:
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name: example-service
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annotations:
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crossplane.io/composition-resource-name: service
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spec:
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type: ClusterIP
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selector:
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app: example
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ports:
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- port: 80
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targetPort: 8080
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status: {}
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---
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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name: example-deployment
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annotations:
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crossplane.io/composition-resource-name: deployment
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spec:
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replicas: 3
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selector:
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matchLabels:
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app: example
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template:
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metadata:
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labels:
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app: example
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spec:
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containers:
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- name: app
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image: nginx:latest
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ports:
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- containerPort: 8080
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status:
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replicas: 3
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updatedReplicas: 3
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availableReplicas: 3
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readyReplicas: 3
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conditions:
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- type: Available
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status: "True"
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reason: MinimumReplicasAvailable
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message: Deployment has minimum availability
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- type: Progressing
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status: "True"
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reason: NewReplicaSetAvailable
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message: ReplicaSet has successfully progressed
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---
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apiVersion: v1
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kind: ConfigMap
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metadata:
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name: example-config
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annotations:
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crossplane.io/composition-resource-name: config
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data:
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config.yaml: |
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key: value

‎fn.go‎

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"github.com/crossplane/function-sdk-go/response"
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xpv1 "github.com/crossplane/crossplane-runtime/apis/common/v1"
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"github.com/crossplane/function-auto-ready/healthchecks"
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)
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// Function returns whatever response you ask it to.
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f.log.Debug("Found desired resources", "count", len(desired))
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// Our goal here is to automatically determine (from the Ready status
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// condition) whether existing composed resources are ready.
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// First, mark standard Kubernetes resources as ready using resource-specific health checks
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for name, dr := range desired {
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log := log.WithValues("composed-resource-name", name)
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// Skip if resource doesn't exist yet
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or, ok := observed[name]
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if !ok {
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continue
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}
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// Skip if readiness already explicitly set
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if dr.Ready != resource.ReadyUnspecified {
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continue
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}
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// Check if this resource type has a registered health check
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// Get GVK from the unstructured object (apiVersion and kind fields)
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// composed.Unstructured embeds unstructured.Unstructured, so we can use it directly
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gvk := or.Resource.GroupVersionKind()
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if healthCheck := healthchecks.GetHealthCheck(gvk); healthCheck != nil {
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log.Debug("Using resource-specific health check", "gvk", gvk.String())
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if healthCheck(&or.Resource.Unstructured) {
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log.Info("Marked resource as ready via resource-specific health check", "gvk", gvk.String())
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dr.Ready = resource.ReadyTrue
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}
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}
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}
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// Second, check remaining resources using the Ready status condition
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for name, dr := range desired {
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log := log.WithValues("composed-resource-name", name)
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