add new manifest deployer update strategies

apis/deployer/manifest/types_provider.go

@@ -47,8 +47,10 @@ type ProviderConfiguration struct {
 type UpdateStrategy string
 
 const (
-	UpdateStrategyUpdate UpdateStrategy = "update"
-	UpdateStrategyPatch  UpdateStrategy = "patch"
+	UpdateStrategyUpdate         UpdateStrategy = "update"
+	UpdateStrategyPatch          UpdateStrategy = "patch"
+	UpdateStrategyMerge          UpdateStrategy = "merge"
+	UpdateStrategyMergeOverwrite UpdateStrategy = "mergeOverwrite"
 )
 
 // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

apis/deployer/manifest/v1alpha2/types_provider.go

@@ -47,8 +47,10 @@ type ProviderConfiguration struct {
 type UpdateStrategy string
 
 const (
-	UpdateStrategyUpdate UpdateStrategy = "update"
-	UpdateStrategyPatch  UpdateStrategy = "patch"
+	UpdateStrategyUpdate         UpdateStrategy = "update"
+	UpdateStrategyPatch          UpdateStrategy = "patch"
+	UpdateStrategyMerge          UpdateStrategy = "merge"
+	UpdateStrategyMergeOverwrite UpdateStrategy = "mergeOverwrite"
 )
 
 // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object

docs/deployer/manifest.md

@@ -30,7 +30,7 @@ spec:
     apiVersion: manifest.deployer.landscaper.gardener.cloud/v1alpha2
     kind: ProviderConfiguration
 
-    updateStrategy: update | patch # optional; defaults to update
+    updateStrategy: update | patch | merge | mergeOverwrite # optional; defaults to update
 
     # Configuration of the readiness checks for the resources.
     # optional
@@ -132,6 +132,14 @@ spec:
           kind: Secret
           jsonPath: ".data.somekey" # points to the value in the resource that is being exported
 ```
+__Update Strategy__:
+
+The update strategy defines the behavior of the manifest deployer when a resource for a rendered manifest already exists on the target cluster.
+
+- `update`: The resources on the cluster will be updated with the results of the rendered manifests (default). Any changes to the resources, applied externally on the cluster, may be lost after the update.
+- `patch`: The manifest deployer will calculate a JSON diff between the resources on the cluster and the rendered manifests. The diff will be applied as a patch. Any changes to the resources, applied externally on the cluster, may be lost after the update.
+- `merge`: The manifest deployer will merge the results of the rendered manifests into the resources on the cluster. Fields that already exist in the resources on the cluster, will not be overwritten.
+- `mergeOverwrite`: The manifest deployer will merge the results of the rendered manifests into the resources on the cluster. Fields that already exist in the resources on the cluster, will be overwritten when the rendered field is not empty.
 
 __Policy__:
 

go.mod

@@ -16,6 +16,7 @@ require (
 	github.com/golang/mock v1.6.0
 	github.com/google/uuid v1.3.0
 	github.com/hashicorp/go-multierror v1.1.1
+	github.com/imdario/mergo v0.3.12
 	github.com/mandelsoft/spiff v1.5.0
 	github.com/mandelsoft/vfs v0.0.0-20210530103237-5249dc39ce91
 	github.com/onsi/ginkgo v1.16.5
@@ -94,7 +95,6 @@ require (
 	github.com/gregjones/httpcache v0.0.0-20190611155906-901d90724c79 // indirect
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/huandu/xstrings v1.3.2 // indirect
-	github.com/imdario/mergo v0.3.12 // indirect
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect
 	github.com/jmoiron/sqlx v1.3.5 // indirect
 	github.com/josharian/intern v1.0.0 // indirect

pkg/deployer/lib/resourcemanager/objectapplier.go

@@ -12,6 +12,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/imdario/mergo"
+
 	corev1 "k8s.io/api/core/v1"
 	extv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
@@ -211,6 +213,7 @@ func (a *ManifestApplier) applyObject(ctx context.Context, manifest *Manifest) (
 			return nil, fmt.Errorf("unable to get object: %w", err)
 		}
 		// inject labels
+		a.injectLabels(obj)
 		kutil.SetMetaDataLabel(obj, manifestv1alpha2.ManagedDeployItemLabel, a.deployItemName)
 		if err := a.kubeClient.Create(ctx, obj); err != nil {
 			return nil, fmt.Errorf("unable to create resource %s: %w", key.String(), err)
@@ -238,24 +241,51 @@ func (a *ManifestApplier) applyObject(ctx context.Context, manifest *Manifest) (
 		return mr, nil
 	}
 
-	// inject manifest specific labels
-	a.injectLabels(obj)
-	kutil.SetMetaDataLabel(obj, manifestv1alpha2.ManagedDeployItemLabel, a.deployItemName)
-
-	// Set the required and immutable fields from the current object.
-	// Update fails if these fields are missing
-	if err := kutil.SetRequiredNestedFieldsFromObj(&currObj, obj); err != nil {
-		return mr, err
-	}
-
 	switch a.updateStrategy {
 	case manifestv1alpha2.UpdateStrategyUpdate:
-		if err := a.kubeClient.Update(ctx, obj); err != nil {
-			return mr, fmt.Errorf("unable to update resource %s: %w", key.String(), err)
-		}
+		fallthrough
 	case manifestv1alpha2.UpdateStrategyPatch:
-		if err := a.kubeClient.Patch(ctx, obj, client.MergeFrom(&currObj)); err != nil {
-			return mr, fmt.Errorf("unable to patch resource %s: %w", key.String(), err)
+		// inject manifest specific labels
+		a.injectLabels(obj)
+		kutil.SetMetaDataLabel(obj, manifestv1alpha2.ManagedDeployItemLabel, a.deployItemName)
+
+		// Set the required and immutable fields from the current object.
+		// Update fails if these fields are missing
+		if err := kutil.SetRequiredNestedFieldsFromObj(&currObj, obj); err != nil {
+			return mr, err
+		}
+
+		if a.updateStrategy == manifestv1alpha2.UpdateStrategyUpdate {
+			if err := a.kubeClient.Update(ctx, obj); err != nil {
+				return mr, fmt.Errorf("unable to update resource %s: %w", key.String(), err)
+			}
+		} else {
+			if err := a.kubeClient.Patch(ctx, obj, client.MergeFrom(&currObj)); err != nil {
+				return mr, fmt.Errorf("unable to patch resource %s: %w", key.String(), err)
+			}
+		}
+	case manifestv1alpha2.UpdateStrategyMerge:
+		fallthrough
+	case manifestv1alpha2.UpdateStrategyMergeOverwrite:
+		var mergeOpts []func(*mergo.Config)
+		if a.updateStrategy == manifestv1alpha2.UpdateStrategyMergeOverwrite {
+			mergeOpts = []func(*mergo.Config){
+				mergo.WithOverride,
+			}
+		} else {
+			mergeOpts = []func(*mergo.Config){}
+		}
+
+		if err := mergo.Merge(&currObj.Object, obj.Object, mergeOpts...); err != nil {
+			return mr, fmt.Errorf("unable to merge changes for resource %s: %w", key.String(), err)
+		}
+
+		// inject manifest specific labels
+		a.injectLabels(&currObj)
+		kutil.SetMetaDataLabel(&currObj, manifestv1alpha2.ManagedDeployItemLabel, a.deployItemName)
+
+		if err := a.kubeClient.Update(ctx, &currObj); err != nil {
+			return mr, fmt.Errorf("unable to update resource %s: %w", key.String(), err)
 		}
 	default:
 		return mr, fmt.Errorf("%s is not a valid update strategy", a.updateStrategy)