skaffold: Rebuild when there are changes to go:embed files

Currently, the ko builder does not detect changes to `go:embed` files (see GoogleContainerTools/skaffold#7836). This makes impossible the development of some scripts that are used later by `go:embed`.
This PR inspires from gardener/gardener#6735 and gardener/gardener#6781 and does the same setup for the registry-cache extension.

Makefile

@@ -74,9 +74,10 @@ check-generate:
 	@$(REPO_ROOT)/vendor/github.com/gardener/gardener/hack/check-generate.sh $(REPO_ROOT)
 
 .PHONY: check
-check: $(GOIMPORTS) $(GOLANGCI_LINT) $(HELM)
+check: $(GOIMPORTS) $(GOLANGCI_LINT) $(HELM) $(YQ)
 	@$(REPO_ROOT)/vendor/github.com/gardener/gardener/hack/check.sh --golangci-lint-config=./.golangci.yaml ./cmd/... ./pkg/... ./test/...
 	@$(REPO_ROOT)/vendor/github.com/gardener/gardener/hack/check-charts.sh ./charts
+	@hack/check-skaffold-deps.sh
 
 .PHONY: generate
 generate: $(CONTROLLER_GEN) $(GEN_CRD_API_REFERENCE_DOCS) $(HELM) $(YQ)

hack/check-skaffold-deps.sh

@@ -0,0 +1,79 @@
+#!/usr/bin/env bash
+#
+# Copyright 2022 SAP SE or an SAP affiliate company. All rights reserved. This file is licensed under the Apache Software License, v. 2 except as noted otherwise in the LICENSE file
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -e
+
+echo "> Check Skaffold Dependencies"
+
+check_successful=true
+
+out_dir=$(mktemp -d)
+function cleanup_output {
+  rm -rf "$out_dir"
+}
+trap cleanup_output EXIT
+
+function check() {
+  skaffold_file="$1"
+  binary_name="$2"
+  skaffold_config_name="$3"
+
+  skaffold_yaml="$(cat "$(dirname "$0")/../$skaffold_file")"
+
+  path_current_skaffold_dependencies="${out_dir}/current-$skaffold_file-deps-$binary_name.txt"
+  path_actual_dependencies="${out_dir}/actual-$skaffold_file-deps-$binary_name.txt"
+
+  echo "$skaffold_yaml" |\
+    yq eval "select(.metadata.name == \"$skaffold_config_name\") | .build.artifacts[] | select(.ko.main == \"./cmd/$binary_name\") | .ko.dependencies.paths[]?" - |\
+    sort |\
+    uniq > "$path_current_skaffold_dependencies"
+
+  go list -f '{{ join .Deps "\n" }}' "./cmd/$binary_name" |\
+    grep "github.com/gardener/gardener-extension-registry-cache/" |\
+    sed 's/github\.com\/gardener\/gardener-extension-registry-cache\///g' |\
+    sort |\
+    uniq > "$path_actual_dependencies"
+
+  # always add vendor directory and VERSION file
+  echo "vendor" >> "$path_actual_dependencies"
+  echo "VERSION" >> "$path_actual_dependencies"
+
+  # sort dependencies
+  sort -o $path_current_skaffold_dependencies{,}
+  sort -o $path_actual_dependencies{,}
+
+  echo -n ">> Checking defined dependencies in Skaffold config '$skaffold_config_name' for '$binary_name' in '$skaffold_file'..."
+  if ! diff="$(diff "$path_current_skaffold_dependencies" "$path_actual_dependencies")"; then
+    check_successful=false
+
+    echo
+    echo ">>> The following actual dependencies are missing in $skaffold_file (need to be added):"
+    echo "$diff" | grep '>' | awk '{print $2}'
+    echo
+    echo ">>> The following dependencies defined in $skaffold_file are not needed actually (need to be removed):"
+    echo "$diff" | grep '<' | awk '{print $2}'
+    echo
+  else
+    echo " success."
+  fi
+}
+
+check "skaffold.yaml" "gardener-extension-registry-cache" "extension"
+check "skaffold.yaml" "gardener-extension-registry-cache-admission" "admission"
+
+if [ "$check_successful" = false ] ; then
+  exit 1
+fi

skaffold.yaml

@@ -7,6 +7,25 @@ build:
   artifacts:
   - image: eu.gcr.io/gardener-project/gardener/extensions/registry-cache
     ko:
+      dependencies:
+        paths:
+        - charts
+        - cmd/gardener-extension-registry-cache/app
+        - pkg/apis/config
+        - pkg/apis/config/v1alpha1
+        - pkg/apis/config/validation
+        - pkg/apis/registry
+        - pkg/apis/registry/install
+        - pkg/apis/registry/v1alpha1
+        - pkg/cmd
+        - pkg/component/registrycaches
+        - pkg/constants
+        - pkg/controller/extension
+        - pkg/imagevector
+        - pkg/utils/registry
+        - pkg/webhook/operatingsystemconfig
+        - vendor
+        - VERSION
       main: ./cmd/gardener-extension-registry-cache
 resourceSelector:
   allow:
@@ -27,6 +46,18 @@ build:
   artifacts:
   - image: eu.gcr.io/gardener-project/gardener/extensions/registry-cache-admission
     ko:
+      dependencies:
+        paths:
+        - cmd/gardener-extension-registry-cache-admission/app
+        - pkg/admission/cmd
+        - pkg/admission/validator
+        - pkg/apis/registry
+        - pkg/apis/registry/install
+        - pkg/apis/registry/v1alpha1
+        - pkg/apis/registry/validation
+        - pkg/constants
+        - vendor
+        - VERSION
       main: ./cmd/gardener-extension-registry-cache-admission
 deploy:
   helm: