Implement DetermineVersions of k8s plugin (#5257)

* Implement DetermineVersions

Signed-off-by: Shinnosuke Sawada-Dazai <shin@warashi.dev>

* Add test cases and fixed the failure

Signed-off-by: Shinnosuke Sawada-Dazai <shin@warashi.dev>

---------

Signed-off-by: Shinnosuke Sawada-Dazai <shin@warashi.dev>

pkg/app/pipedv1/plugin/kubernetes/deployment/determine.go

@@ -0,0 +1,91 @@
+// Copyright 2024 The PipeCD Authors.
+//
+// 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.
+
+package deployment
+
+import (
+	"fmt"
+	"strings"
+
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+
+	"github.com/pipe-cd/pipecd/pkg/app/pipedv1/plugin/kubernetes/provider"
+	"github.com/pipe-cd/pipecd/pkg/model"
+)
+
+type containerImage struct {
+	name string
+	tag  string
+}
+
+// parseContainerImage splits the container image into name and tag.
+// The image should be in the format of "name:tag".
+// If the tag is not specified, it will be empty.
+func parseContainerImage(image string) (img containerImage) {
+	parts := strings.Split(image, ":")
+	if len(parts) == 2 {
+		img.tag = parts[1]
+	}
+	paths := strings.Split(parts[0], "/")
+	img.name = paths[len(paths)-1]
+	return
+}
+
+// determineVersions decides artifact versions of an application.
+// It finds all container images that are being specified in the workload manifests then returns their names and tags.
+func determineVersions(manifests []provider.Manifest) ([]*model.ArtifactVersion, error) {
+	imageMap := map[string]struct{}{}
+	for _, m := range manifests {
+		// TODO: we should consider other fields like spec.jobTempate.spec.template.spec.containers because CronJob uses this format.
+		containers, ok, err := unstructured.NestedSlice(m.Body.Object, "spec", "template", "spec", "containers")
+		if err != nil {
+			// if the containers field is not an array, it will return an error.
+			// we define this as error because the 'containers' is plural form, so it should be an array.
+			return nil, err
+		}
+		if !ok {
+			continue
+		}
+		// Remove duplicate images on multiple manifests.
+		for _, c := range containers {
+			m, ok := c.(map[string]interface{})
+			if !ok {
+				// TODO: Add logging.
+				continue
+			}
+			img, ok := m["image"]
+			if !ok {
+				continue
+			}
+			imgStr, ok := img.(string)
+			if !ok {
+				return nil, fmt.Errorf("invalid image format: %T(%v)", img, img)
+			}
+			imageMap[imgStr] = struct{}{}
+		}
+	}
+
+	versions := make([]*model.ArtifactVersion, 0, len(imageMap))
+	for i := range imageMap {
+		image := parseContainerImage(i)
+		versions = append(versions, &model.ArtifactVersion{
+			Kind:    model.ArtifactVersion_CONTAINER_IMAGE,
+			Version: image.tag,
+			Name:    image.name,
+			Url:     i,
+		})
+	}
+
+	return versions, nil
+}