pkg/resource: add LogDiff apply option

Signed-off-by: Dr. Stefan Schimanski <[email protected]>

pkg/logging/logging.go

@@ -38,6 +38,7 @@ package logging
 
 import (
 	"github.com/go-logr/logr"
+	"sigs.k8s.io/controller-runtime/pkg/client"
 )
 
 // A Logger logs messages. Messages may be supplemented by structured data.
@@ -92,3 +93,18 @@ func (l logrLogger) Debug(msg string, keysAndValues ...any) {
 func (l logrLogger) WithValues(keysAndValues ...any) Logger {
 	return logrLogger{log: l.log.WithValues(keysAndValues...)} //nolint:logrlint // False positive - logrlint thinks there's an odd number of args.
 }
+
+// ForResource returns logging values for a resource.
+func ForResource(object client.Object) []string {
+	ret := make([]string, 0, 10)
+	ret = append(ret, "name", object.GetName())
+	if ns := object.GetNamespace(); ns != "" {
+		ret = append(ret, "namespace", ns)
+	}
+	gvk := object.GetObjectKind().GroupVersionKind()
+	ret = append(ret, "kind", gvk.Kind)
+	ret = append(ret, "version", gvk.Version)
+	ret = append(ret, "group", gvk.Group)
+
+	return ret
+}

pkg/resource/providerconfig.go

@@ -29,6 +29,7 @@ import (
 
 	xpv1 "github.com/crossplane/crossplane-runtime/apis/common/v1"
 	"github.com/crossplane/crossplane-runtime/pkg/errors"
+	"github.com/crossplane/crossplane-runtime/pkg/logging"
 	"github.com/crossplane/crossplane-runtime/pkg/meta"
 )
 
@@ -123,13 +124,20 @@ func (fn TrackerFn) Track(ctx context.Context, mg Managed) error {
 // A ProviderConfigUsageTracker tracks usages of a ProviderConfig by creating or
 // updating the appropriate ProviderConfigUsage.
 type ProviderConfigUsageTracker struct {
-	c  Applicator
-	of ProviderConfigUsage
+	c   Applicator
+	of  ProviderConfigUsage
+	log logging.Logger
 }
 
 // NewProviderConfigUsageTracker creates a ProviderConfigUsageTracker.
 func NewProviderConfigUsageTracker(c client.Client, of ProviderConfigUsage) *ProviderConfigUsageTracker {
-	return &ProviderConfigUsageTracker{c: NewAPIUpdatingApplicator(c), of: of}
+	return &ProviderConfigUsageTracker{c: NewAPIUpdatingApplicator(c), of: of, log: logging.NewNopLogger()}
+}
+
+// WithLogger adds a logger to the ProviderConfigUsageTracker.
+func (u *ProviderConfigUsageTracker) WithLogger(l logging.Logger) *ProviderConfigUsageTracker {
+	u.log = l
+	return u
 }
 
 // Track that the supplied Managed resource is using the ProviderConfig it
@@ -160,6 +168,7 @@ func (u *ProviderConfigUsageTracker) Track(ctx context.Context, mg Managed) erro
 		AllowUpdateIf(func(current, _ runtime.Object) bool {
 			return current.(ProviderConfigUsage).GetProviderConfigReference() != pcu.GetProviderConfigReference()
 		}),
+		LogDiff(u.log.WithValues(logging.ForResource(pcu))),
 	)
 	return errors.Wrap(Ignore(IsNotAllowed, err), errApplyPCU)
 }

pkg/resource/resource.go

@@ -18,8 +18,10 @@ package resource
 
 import (
 	"context"
+	"encoding/json"
 	"strings"
 
+	jsonpatch "github.com/evanphx/json-patch/v5"
 	corev1 "k8s.io/api/core/v1"
 	kerrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -32,6 +34,7 @@ import (
 
 	xpv1 "github.com/crossplane/crossplane-runtime/apis/common/v1"
 	"github.com/crossplane/crossplane-runtime/pkg/errors"
+	"github.com/crossplane/crossplane-runtime/pkg/logging"
 	"github.com/crossplane/crossplane-runtime/pkg/meta"
 )
 
@@ -299,6 +302,28 @@ func UpdateFn(fn func(current, desired runtime.Object)) ApplyOption {
 	}
 }
 
+// LogDiff returns an ApplyOption that logs the difference between the current and desired state.
+func LogDiff(log logging.Logger) func(ctx context.Context, current, desired runtime.Object) error {
+	return func(ctx context.Context, current, desired runtime.Object) error {
+		oldData, err := json.Marshal(current)
+		if err != nil {
+			return errors.Wrapf(err, "failed to Marshal old data for %T", current)
+		}
+		newData, err := json.Marshal(desired)
+		if err != nil {
+			return errors.Wrapf(err, "failed to Marshal new data for %T", desired)
+		}
+		patchBytes, err := jsonpatch.CreateMergePatch(oldData, newData)
+		if err != nil {
+			return errors.Wrapf(err, "failed to create patch for %T", current)
+		}
+
+		log.WithValues("diff", string(patchBytes)).Info("patching object")
+
+		return nil
+	}
+}
+
 type errNotControllable struct{ error }
 
 func (e errNotControllable) NotControllable() bool {