feat: add expression method to get value (#1841)

Signed-off-by: Charles-Edouard Brétéché <charles.edouard@nirmata.com>

pkg/apis/v1alpha1/types.go

@@ -1,9 +1,12 @@
 package v1alpha1
 
 import (
+	"context"
 	"fmt"
 	"regexp"
 
+	"github.com/jmespath-community/go-jmespath/pkg/binding"
+	"github.com/kyverno/chainsaw/pkg/expressions"
 	"github.com/kyverno/kyverno-json/pkg/apis/policy/v1alpha1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
@@ -62,6 +65,10 @@ type Expectation struct {
 // Expression defines an expression to be used in string fields.
 type Expression string
 
+func (e Expression) Value(ctx context.Context, bindings binding.Bindings) (string, error) {
+	return expressions.String(ctx, string(e), bindings)
+}
+
 // Format determines the output format (json or yaml).
 // +kubebuilder:validation:Pattern=`^(?:json|yaml|\(.+\))$`
 type Format string

pkg/runner/processors/step.go

@@ -25,7 +25,6 @@ import (
 	opscript "github.com/kyverno/chainsaw/pkg/engine/operations/script"
 	opsleep "github.com/kyverno/chainsaw/pkg/engine/operations/sleep"
 	opupdate "github.com/kyverno/chainsaw/pkg/engine/operations/update"
-	"github.com/kyverno/chainsaw/pkg/expressions"
 	"github.com/kyverno/chainsaw/pkg/loaders/resource"
 	"github.com/kyverno/chainsaw/pkg/report"
 	"github.com/kyverno/chainsaw/pkg/runner/failer"
@@ -1087,7 +1086,7 @@ func (p *stepProcessor) fileRefOrCheck(ctx context.Context, ref v1alpha1.ActionC
 		}
 	}
 	if ref.File != "" {
-		ref, err := expressions.String(ctx, string(ref.File), bindings)
+		ref, err := ref.File.Value(ctx, bindings)
 		if err != nil {
 			return nil, err
 		}
@@ -1106,7 +1105,7 @@ func (p *stepProcessor) fileRefOrResource(ctx context.Context, ref v1alpha1.Acti
 		return []unstructured.Unstructured{*ref.Resource}, nil
 	}
 	if ref.File != "" {
-		ref, err := expressions.String(ctx, string(ref.File), bindings)
+		ref, err := ref.File.Value(ctx, bindings)
 		if err != nil {
 			return nil, err
 		}