Add request.body in CEL notification filtering

This moves the JSON body to request.body from request to allow for
future expansion with the headers.

Add documentation

Signed-off-by: Kevin McDermott <[email protected]>

Author: bigkevmcd

docs/spec/v1/receivers.md

@@ -700,6 +700,55 @@ resources:
 **Note:** Cross-namespace references [can be disabled for security
 reasons](#disabling-cross-namespace-selectors).
 
+#### Filtering reconciled objects with CEL
+
+To filter the resources that are reconciled you can use [Common Expression Language (CEL)](https://cel.dev/).
+
+For example to trigger `ImageRepositories` on notifications from [Google Artifact Regisry](https://cloud.google.com/artifact-registry/docs/configure-notifications#examples) you can define a receiver.
+
+```yaml
+apiVersion: notification.toolkit.fluxcd.io/v1
+kind: Receiver
+metadata:
+  name: gar-receiver
+  namespace: apps
+spec:
+  type: gcr
+  secretRef:
+    name: flux-gar-token
+  resources:
+    - apiVersion: image.toolkit.fluxcd.io/v1beta2
+      kind: ImageRepository
+      name: "*"
+      matchLabels:
+        registry: gar
+```
+
+This will trigger the reconciliation of all `ImageRepositories` with matching labels `registry: gar`, but if you want to only notify `ImageRepository` resources that are referenced from the incoming hook you can use CEL to filter the resources.
+
+```yaml
+apiVersion: notification.toolkit.fluxcd.io/v1
+kind: Receiver
+metadata:
+  name: gar-receiver
+  namespace: apps
+spec:
+  type: gcr
+  secretRef:
+    name: flux-gar-token
+  resources:
+    - apiVersion: image.toolkit.fluxcd.io/v1beta2
+      kind: ImageRepository
+      name: "*"
+      matchLabels:
+        registry: gar
+  resourceFilter: 'request.tag.contains(resource.metadata.name)'
+```
+
+To reduce the number of `ImageRepositories` that are reconciled, you can filter them with a CEL expression.
+
+```
+
 ### Secret reference
 
 `.spec.secretRef.name` is a required field to specify a name reference to a

internal/server/cel.go

@@ -53,7 +53,9 @@ func newCELEvaluator(expr string, req *http.Request) (resourcePredicate, error)
 
 		out, _, err := prg.Eval(map[string]any{
 			"resource": data,
-			"request":  body,
+			"request": map[string]any{
+				"body": body,
+			},
 		})
 		if err != nil {
 			return nil, fmt.Errorf("expression %v failed to evaluate: %w", expr, err)
@@ -74,7 +76,6 @@ func makeCELEnv() (*cel.Env, error) {
 	mapStrDyn := decls.NewMapType(decls.String, decls.Dyn)
 	return cel.NewEnv(
 		celext.Strings(),
-		celext.Encoders(),
 		notifications(),
 		cel.Declarations(
 			decls.NewVar("resource", mapStrDyn),

internal/server/receiver_handler_test.go

@@ -789,7 +789,7 @@ func Test_handlePayload(t *testing.T) {
 							},
 						},
 					},
-					ResourceFilter: `has(resource.metadata.annotations) && request.tag.split('/').last().split(":").first() == resource.metadata.annotations['update-image']`,
+					ResourceFilter: `has(resource.metadata.annotations) && request.body.tag.split('/').last().split(":").first() == resource.metadata.annotations['update-image']`,
 				},
 				Status: apiv1.ReceiverStatus{
 					WebhookPath: apiv1.ReceiverWebhookPath,
@@ -878,7 +878,7 @@ func Test_handlePayload(t *testing.T) {
 							Name:       "test-resource",
 						},
 					},
-					ResourceFilter: `has(resource.metadata.annotations) && request.tag.split('/').last().split(":").first() == resource.metadata.annotations['update-image']`,
+					ResourceFilter: `has(resource.metadata.annotations) && request.body.tag.split('/').last().split(":").first() == resource.metadata.annotations['update-image']`,
 				},
 				Status: apiv1.ReceiverStatus{
 					WebhookPath: apiv1.ReceiverWebhookPath,