diff: add premature diff debug log

As there are currently no other utilities to properly see what change
the controller detected, this allows people to have an insight into
the observed changes by configuring the controller with
`--log-level=debug`.

Signed-off-by: Hidde Beydals <hidde@hhh.computer>

Author: hiddeco

internal/diff/differ.go

@@ -19,6 +19,10 @@ package diff
 import (
 	"context"
 	"fmt"
+	"github.com/fluxcd/pkg/runtime/logger"
+	"github.com/google/go-cmp/cmp"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	ctrl "sigs.k8s.io/controller-runtime"
 	"strings"
 
 	"helm.sh/helm/v3/pkg/release"
@@ -105,7 +109,7 @@ func (d *Differ) Diff(ctx context.Context, rel *release.Release) (*ssa.ChangeSet
 			}
 		}
 
-		entry, _, _, err := resourceManager.Diff(ctx, obj, ssa.DiffOptions{
+		entry, releaseObject, clusterObject, err := resourceManager.Diff(ctx, obj, ssa.DiffOptions{
 			Exclusions: map[string]string{
 				MetadataKey: MetadataDisabledValue,
 			},
@@ -118,6 +122,15 @@ func (d *Differ) Diff(ctx context.Context, rel *release.Release) (*ssa.ChangeSet
 		case ssa.CreatedAction, ssa.ConfiguredAction:
 			diff = true
 			changeSet.Add(*entry)
+
+			if entry.Action == ssa.ConfiguredAction {
+				// TODO: remove this once we have a better way to log the diff
+				//       for example using a custom dyff reporter, or a flux CLI command
+				ctrl.LoggerFrom(ctx).V(logger.DebugLevel).Info(entry.Subject + " diff:" + cmp.Diff(
+					unstructuredWithoutStatus(releaseObject).UnstructuredContent(),
+					unstructuredWithoutStatus(clusterObject).UnstructuredContent(),
+				))
+			}
 		case ssa.SkippedAction:
 			changeSet.Add(*entry)
 		}
@@ -129,3 +142,9 @@ func (d *Differ) Diff(ctx context.Context, rel *release.Release) (*ssa.ChangeSet
 	}
 	return changeSet, diff, err
 }
+
+func unstructuredWithoutStatus(obj *unstructured.Unstructured) *unstructured.Unstructured {
+	obj = obj.DeepCopy()
+	delete(obj.Object, "status")
+	return obj
+}