implement Trait patch back before workload emitted

apis/core/v1alpha2/core_types.go

@@ -80,6 +80,10 @@ type WorkloadDefinitionList struct {
 
 // A TraitDefinitionSpec defines the desired state of a TraitDefinition.
 type TraitDefinitionSpec struct {
+	// Flags whether the trait is separate from the underlying workload
+	// +optional
+	Patch bool `json:"patch,omitempty"`
+
 	// Reference to the CustomResourceDefinition that defines this trait kind.
 	Reference DefinitionReference `json:"definitionRef"`
 

charts/oam-kubernetes-runtime/crds/core.oam.dev_traitdefinitions.yaml

@@ -68,6 +68,10 @@ spec:
                 description: Extension is used for extension needs by OAM platform
                   builders
                 type: object
+              patch:
+                description: Flags whether the trait is separate from the underlying
+                  workload
+                type: boolean
               revisionEnabled:
                 description: Revision indicates whether a trait is aware of component
                   revision

examples/trait-separated/README.md

@@ -0,0 +1,123 @@
+## How do I add trait with patch fragments
+
+### Prerequisites
+* [Install OAM Runtime](https://github.com/crossplane/oam-kubernetes-runtime#install-oam-runtime) 
+
+
+### Install traits with patch fragments
+
+* Install the Trait Definition
+
+```
+apiVersion: core.oam.dev/v1alpha2
+kind: TraitDefinition
+metadata:
+  name: nodeselectors.extended.oam.dev
+spec:
+  patch: true 
+  appliesToWorkloads:
+    - core.oam.dev/v1alpha2.ContainerizedWorkload
+  definitionRef:
+    name: nodeselectors.extended.oam.dev
+```
+* Install NodeSelector Controller
+
+
+* Add traits with patch fragments to the ApplicationConfiguration
+
+`sample_application_config.yaml`
+
+```
+apiVersion: core.oam.dev/v1alpha2
+kind: ApplicationConfiguration
+metadata:
+  name: example-appconfig
+spec:
+  components:
+    - componentName: example-component
+      parameterValues:
+        - name: instance-name
+          value: example-appconfig-workload
+        - name: image
+          value: wordpress:php7.2
+      traits:
+        - trait:
+            apiVersion: core.oam.dev/v1alpha2
+            kind: ManualScalerTrait
+            metadata:
+              name: example-appconfig-trait
+            spec:
+              replicaCount: 3
+        - trait:
+            apiVersion: extended.oam.dev/v1alpha2
+            kind: NodeSelector
+            metadata:
+              name: example-appconfig-nodeselector
+            spec:
+              disktype: ssd
+      scopes:
+        - scopeRef:
+            apiVersion: core.oam.dev/v1alpha2
+            kind: HealthScope
+            name: example-health-scope
+```
+
+
+* Apply a sample application configuration
+
+```
+# kubectl apply -f sample_application_config.yaml
+
+```
+* Check the status of the Trait and confirm whether the value of patchConfig is set successfully
+
+```
+# kubectl get NodeSelector  example-appconfig-nodeselector
+```
+
+```
+apiVersion: extended.oam.dev/v1alpha2
+kind: NodeSelector
+metadata:
+  name: example-component-trait-6db9578cfd
+spec:
+  disktype: ssd
+status:
+  patchConfig: nodeselector-cm
+  phase: Ready
+```
+
+
+### Query ConfigMap content to confirm whether the Patch data is correct
+
+```
+# kubectl get cm nodeselector-cm -o yaml
+```
+
+```
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: nodeselector-cm
+data:
+  patch: |
+    {
+      "spec": {
+        "template": {
+          "spec": {
+            "nodeSelector": {
+              "disktype": "ssd"
+            }
+          }
+        }
+      }
+    }
+
+```
+
+### Check the Spec content of the Workload
+
+```
+# kubectl get deployment example-appconfig-workload -o yaml
+
+```

go.mod

@@ -5,17 +5,19 @@ go 1.13
 require (
 	github.com/crossplane/crossplane-runtime v0.8.0
 	github.com/davecgh/go-spew v1.1.1
+	github.com/evanphx/json-patch v4.5.0+incompatible
 	github.com/gertd/go-pluralize v0.1.7
 	github.com/go-logr/logr v0.1.0
 	github.com/google/go-cmp v0.4.0
+	github.com/imdario/mergo v0.3.7
 	github.com/json-iterator/go v1.1.8
 	github.com/onsi/ginkgo v1.11.0
 	github.com/onsi/gomega v1.8.1
 	github.com/pkg/errors v0.9.1
 	github.com/rs/xid v1.2.1
 	github.com/stretchr/testify v1.4.0
 	go.uber.org/zap v1.10.0
-	golang.org/x/tools v0.0.0-20200630223951-c138986dd9b9 // indirect
+	golang.org/x/tools v0.0.0-20200630223951-c138986dd9b9
 	gopkg.in/natefinch/lumberjack.v2 v2.0.0
 	k8s.io/api v0.18.5
 	k8s.io/apiextensions-apiserver v0.18.2

pkg/controller/v1alpha2/applicationconfiguration/render.go

@@ -20,10 +20,12 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"strings"
 
 	runtimev1alpha1 "github.com/crossplane/crossplane-runtime/apis/core/v1alpha1"
 	"github.com/crossplane/crossplane-runtime/pkg/fieldpath"
 	"github.com/crossplane/crossplane-runtime/pkg/resource"
+	jsonpatch "github.com/evanphx/json-patch"
 	"github.com/pkg/errors"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -44,15 +46,24 @@ const (
 
 // Render error format strings.
 const (
-	errFmtGetComponent     = "cannot get component %q"
-	errFmtGetScope         = "cannot get scope %q"
-	errFmtResolveParams    = "cannot resolve parameter values for component %q"
-	errFmtRenderWorkload   = "cannot render workload for component %q"
-	errFmtRenderTrait      = "cannot render trait for component %q"
-	errFmtSetParam         = "cannot set parameter %q"
-	errFmtUnsupportedParam = "unsupported parameter %q"
-	errFmtRequiredParam    = "required parameter %q not specified"
-	errSetValueForField    = "can not set value %q for fieldPath %q"
+	errFmtGetComponent          = "cannot get component %q"
+	errFmtGetScope              = "cannot get scope %q"
+	errFmtResolveParams         = "cannot resolve parameter values for component %q"
+	errFmtRenderWorkload        = "cannot render workload for component %q"
+	errFmtRenderTrait           = "cannot render trait for component %q"
+	errFmtSetParam              = "cannot set parameter %q"
+	errFmtUnsupportedParam      = "unsupported parameter %q"
+	errFmtRequiredParam         = "required parameter %q not specified"
+	errSetValueForField         = "can not set value %q for fieldPath %q"
+	errGetConfigMapValueForName = "can not get configMap data for configMapName %q"
+	errNoSuchField              = "status: no such field"
+)
+
+const (
+	//StatusKey stands for the status field of the spec
+	StatusKey      = "status"
+	patchConfigKey = "patchConfig"
+	patchKey       = "patch"
 )
 
 var (
@@ -88,18 +99,21 @@ func (r *components) Render(ctx context.Context, ac *v1alpha2.ApplicationConfigu
 	workloads := make([]*Workload, 0, len(ac.Spec.Components))
 	dag := newDAG()
 
+	newComponents := make([]v1alpha2.ApplicationConfigurationComponent, 0)
 	for _, acc := range ac.Spec.Components {
-		w, err := r.renderComponent(ctx, acc, ac, dag)
+		acc := acc
+		w, err := r.renderComponent(ctx, &acc, ac, dag)
 		if err != nil {
 			return nil, nil, err
 		}
 
 		workloads = append(workloads, w)
+		newComponents = append(newComponents, acc)
 	}
 
 	ds := &v1alpha2.DependencyStatus{}
-	res := make([]Workload, 0, len(ac.Spec.Components))
-	for i, acc := range ac.Spec.Components {
+	res := make([]Workload, 0, len(newComponents))
+	for i, acc := range newComponents {
 		unsatisfied, err := r.handleDependency(ctx, workloads[i], acc, dag)
 		if err != nil {
 			return nil, nil, err
@@ -111,11 +125,12 @@ func (r *components) Render(ctx context.Context, ac *v1alpha2.ApplicationConfigu
 	return res, ds, nil
 }
 
-func (r *components) renderComponent(ctx context.Context, acc v1alpha2.ApplicationConfigurationComponent, ac *v1alpha2.ApplicationConfiguration, dag *dag) (*Workload, error) {
+func (r *components) renderComponent(ctx context.Context, acc *v1alpha2.ApplicationConfigurationComponent, ac *v1alpha2.ApplicationConfiguration, dag *dag) (*Workload, error) {
 	if acc.RevisionName != "" {
 		acc.ComponentName = ExtractComponentName(acc.RevisionName)
 	}
-	c, componentRevisionName, err := util.GetComponent(ctx, r.client, acc, ac.GetNamespace())
+
+	c, componentRevisionName, err := util.GetComponent(ctx, r.client, *acc, ac.GetNamespace())
 	if err != nil {
 		return nil, err
 	}
@@ -139,10 +154,17 @@ func (r *components) renderComponent(ctx context.Context, acc v1alpha2.Applicati
 	traits := make([]*Trait, 0, len(acc.Traits))
 	traitDefs := make([]v1alpha2.TraitDefinition, 0, len(acc.Traits))
 	for _, ct := range acc.Traits {
-		t, traitDef, err := r.renderTrait(ctx, ct, ac, acc.ComponentName, ref, dag)
+		ct := ct
+		t, traitDef, err := r.renderTrait(ctx, &ct, ac, acc.ComponentName, ref, dag)
 		if err != nil {
 			return nil, err
 		}
+		//Render patch data
+		if traitDef.Spec.Patch {
+			if err := r.renderComponentFromPatchTrait(ctx, w, acc, t); err != nil {
+				return nil, err
+			}
+		}
 
 		// pass through labels and annotation from app-config to trait
 		r.passThroughObjMeta(ac.ObjectMeta, t)
@@ -168,26 +190,87 @@ func (r *components) renderComponent(ctx context.Context, acc v1alpha2.Applicati
 	return &Workload{ComponentName: acc.ComponentName, ComponentRevisionName: componentRevisionName, Workload: w, Traits: traits, Scopes: scopes}, nil
 }
 
-func (r *components) renderTrait(ctx context.Context, ct v1alpha2.ComponentTrait, ac *v1alpha2.ApplicationConfiguration,
+func (r *components) renderComponentFromPatchTrait(ctx context.Context, w *unstructured.Unstructured, acc *v1alpha2.ApplicationConfigurationComponent, t *unstructured.Unstructured) error {
+	dataInput := v1alpha2.DataInput{
+		ValueFrom: v1alpha2.DataInputValueFrom{
+			DataOutputName: t.GetName(),
+		},
+	}
+	acc.DataInputs = append(acc.DataInputs, dataInput)
+	//get trait status
+	targetTraitObject := &unstructured.Unstructured{}
+	targetTraitObject.SetGroupVersionKind(t.GroupVersionKind())
+	if err := r.client.Get(ctx, types.NamespacedName{Name: t.GetName(), Namespace: t.GetNamespace()}, targetTraitObject); err != nil {
+		return err
+	}
+
+	smap, err := fieldpath.Pave(targetTraitObject.Object).GetStringObject(StatusKey)
+	if err != nil && !strings.ContainsAny(err.Error(), errNoSuchField) {
+		return err
+	}
+	patchCmName := smap[patchConfigKey]
+	if len(smap) == 0 || patchCmName == "" {
+		return nil
+	}
+	//patch yaml
+	nn := types.NamespacedName{Namespace: w.GetNamespace(), Name: patchCmName}
+	cm := &corev1.ConfigMap{}
+	var patch string
+	if err := r.client.Get(ctx, nn, cm); err != nil {
+		return err
+	}
+
+	if patch = cm.Data[patchKey]; patch == "" {
+		return errors.Wrapf(err, errGetConfigMapValueForName, nn.Name)
+	}
+
+	workloadJSON, err := w.MarshalJSON()
+	if err != nil {
+		return err
+	}
+
+	workloadFullJSON, err := jsonpatch.MergeMergePatches(workloadJSON, []byte(patch))
+	if err != nil {
+		return err
+	}
+
+	var mergePatchObject map[string]interface{}
+	if err = json.Unmarshal(workloadFullJSON, &mergePatchObject); err != nil {
+		return err
+	}
+	w.SetUnstructuredContent(mergePatchObject)
+	return nil
+}
+
+func (r *components) renderTrait(ctx context.Context, ct *v1alpha2.ComponentTrait, ac *v1alpha2.ApplicationConfiguration,
 	componentName string, ref *metav1.OwnerReference, dag *dag) (*unstructured.Unstructured, *v1alpha2.TraitDefinition, error) {
 	t, err := r.trait.Render(ct.Trait.Raw)
 	if err != nil {
 		return nil, nil, errors.Wrapf(err, errFmtRenderTrait, componentName)
 	}
 
-	traitName := getTraitName(ac, componentName, &ct, t)
+	traitName := getTraitName(ac, componentName, ct, t)
 
 	setTraitProperties(t, traitName, ac.GetNamespace(), ref)
 
 	traitDef, err := util.FetchTraitDefinition(ctx, r.client, t)
 	if err != nil {
 		return nil, nil, errors.Wrapf(err, errFmtGetTraitDefinition, t.GetAPIVersion(), t.GetKind(), t.GetName())
 	}
-
+	if traitDef.Spec.Patch {
+		r.renderTraitWithOutput(ct, t.GetName())
+	}
 	addDataOutputsToDAG(dag, ct.DataOutputs, t)
-
 	return t, traitDef, nil
 }
+func (r *components) renderTraitWithOutput(ct *v1alpha2.ComponentTrait, traitName string) {
+	//output data
+	dataOutput := v1alpha2.DataOutput{
+		Name:      traitName,
+		FieldPath: fmt.Sprintf("%s.%s", StatusKey, patchConfigKey),
+	}
+	ct.DataOutputs = append(ct.DataOutputs, dataOutput)
+}
 
 func (r *components) renderScope(ctx context.Context, cs v1alpha2.ComponentScope, ns string) (*unstructured.Unstructured, error) {
 	// Get Scope instance from k8s, since it is global and not a child resource of workflow.