Support serialization of objects as string using json/yaml format #843
Description
Feature Description
Problem Statement:
As part of RGD, I need to combine various pieces for worker configuration to be mounted as file from configMap, for example.
apiVersion: kro.run/v1alpha1
kind: ResourceGraphDefinition
metadata:
name: app
spec:
schema:
apiVersion: v1alpha1
kind: App
spec:
config: object
resources:
- id: configMap
template:
apiVersion: v1
kind: ConfigMap
metadata:
name: ${schema.metadata.name}
data:
config.yaml: |
${schema.spec.config}
Logs:
2025-11-21T10:20:53.901Z DEBUG rgd-controller setting resourcegraphdefinition as managed {"controller": "ResourceGraphDefinition", "controllerGroup": "kro.run", "controllerKind": "ResourceGraphDefinition", "name": "app", "reconcileID": "ee549285-bad9-49b3-a453-c9e6664a427d"}
2025-11-21T10:20:53.901Z DEBUG rgd-controller reconciling resource graph definition graph {"controller": "ResourceGraphDefinition", "controllerGroup": "kro.run", "controllerKind": "ResourceGraphDefinition", "name": "app", "reconcileID": "ee549285-bad9-49b3-a453-c9e6664a427d"}
2025-11-21T10:20:53.902Z DEBUG rgd-controller calculating resource graph definition status and conditions {"controller": "ResourceGraphDefinition", "controllerGroup": "kro.run", "controllerKind": "ResourceGraphDefinition", "name": "app", "reconcileID": "ee549285-bad9-49b3-a453-c9e6664a427d"}
2025-11-21T10:20:53.902Z DEBUG rgd-controller updating resource graph definition status {"controller": "ResourceGraphDefinition", "controllerGroup": "kro.run", "controllerKind": "ResourceGraphDefinition", "name": "app", "reconcileID": "ee549285-bad9-49b3-a453-c9e6664a427d", "state": "Inactive", "conditions": 4}
2025-11-21T10:20:53.903Z ERROR rgd-controller Reconciler error {"controller": "ResourceGraphDefinition", "controllerGroup": "kro.run", "controllerKind": "ResourceGraphDefinition", "name": "app", "reconcileID": "ee549285-bad9-49b3-a453-c9e6664a427d", "error": "failed to validate node \"configMap\": type mismatch in resource \"configMap\" at path \"data[\\\"config.yaml\\\"]\": expression \"schema.spec.config\" returns type \"__type_schema.spec.config\" but expected \"string\": type kind mismatch: got \"__type_schema.spec.config\", expected \"string\""}
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).reconcileHandler
sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:316
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).processNextWorkItem
sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:263
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).Start.func2.2
sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:224
Logs for ${string(schema.spec.config)}:
2025-11-21T10:23:27.511Z DEBUG rgd-controller setting resourcegraphdefinition as managed {"controller": "ResourceGraphDefinition", "controllerGroup": "kro.run", "controllerKind": "ResourceGraphDefinition", "name": "app", "reconcileID": "4607b587-a4b8-4185-929b-92ed86ebfae0"}
2025-11-21T10:23:27.511Z DEBUG rgd-controller reconciling resource graph definition graph {"controller": "ResourceGraphDefinition", "controllerGroup": "kro.run", "controllerKind": "ResourceGraphDefinition", "name": "app", "reconcileID": "4607b587-a4b8-4185-929b-92ed86ebfae0"}
2025-11-21T10:23:27.514Z DEBUG rgd-controller calculating resource graph definition status and conditions {"controller": "ResourceGraphDefinition", "controllerGroup": "kro.run", "controllerKind": "ResourceGraphDefinition", "name": "app", "reconcileID": "4607b587-a4b8-4185-929b-92ed86ebfae0"}
2025-11-21T10:23:27.514Z DEBUG rgd-controller updating resource graph definition status {"controller": "ResourceGraphDefinition", "controllerGroup": "kro.run", "controllerKind": "ResourceGraphDefinition", "name": "app", "reconcileID": "4607b587-a4b8-4185-929b-92ed86ebfae0", "state": "Inactive", "conditions": 4}
2025-11-21T10:23:27.514Z ERROR rgd-controller Reconciler error {"controller": "ResourceGraphDefinition", "controllerGroup": "kro.run", "controllerKind": "ResourceGraphDefinition", "name": "app", "reconcileID": "4607b587-a4b8-4185-929b-92ed86ebfae0", "error": "failed to validate node \"configMap\": failed to type-check template expression \"string(schema.spec.config)\" at path \"data[\\\"config.yaml\\\"]\": ERROR: <input>:1:7: found no matching overload for 'string' applied to '(__type_schema.spec.config)'\n | string(schema.spec.config)\n | ......^"}
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).reconcileHandler
sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:316
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).processNextWorkItem
sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:263
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).Start.func2.2
sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:224
Proposed Solution:
Additional functions to dump content with yaml/json formatting
${toYaml(schema.spec.config)} and/or ${toJson(schema.spec.config)}
Alternatives Considered:
Currently, such configuration could be referenced outside the RGD but it will lack some additional properties which are computed as part of instance deployment.
Additional Context:
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