There is not really a reason to use components at the moment

common/postgres/cluster.yaml

@@ -1,7 +1,7 @@
 apiVersion: postgresql.cnpg.io/v1
 kind: Cluster
 metadata:
-  name: -db
+  name: postgres
 spec:
   instances: 2
 

common/postgres/kustomization.yaml

@@ -1,7 +1,4 @@
-apiVersion: kustomize.config.k8s.io/v1alpha1
-kind: Component
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
 resources:
   - ./cluster.yaml
-
-replacements:
-  - path: replacement.yaml

common/postgres/replacement.yaml

@@ -1,12 +0,0 @@
-source:
-  kind: Namespace
-  fieldPath: metadata.name
-targets:
-  - select:
-      kind: Cluster
-      name: -db
-    fieldPaths:
-      - metadata.name
-    options:
-      delimiter: "-"
-      index: 0