Refactor kubernetes provider by separating Loader and Applier

pkg/app/piped/cloudprovider/kubernetes/BUILD.bazel

@@ -3,6 +3,7 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 go_library(
     name = "go_default_library",
     srcs = [
+        "applier.go",
         "cache.go",
         "deployment.go",
         "diff.go",
@@ -12,6 +13,7 @@ go_library(
         "kubectl.go",
         "kubernetes.go",
         "kustomize.go",
+        "loader.go",
         "manifest.go",
         "resourcekey.go",
         "state.go",

pkg/app/piped/cloudprovider/kubernetes/applier.go

@@ -0,0 +1,131 @@
+// Copyright 2022 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 kubernetes
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"sync"
+
+	"go.uber.org/zap"
+
+	"github.com/pipe-cd/pipecd/pkg/app/piped/toolregistry"
+	"github.com/pipe-cd/pipecd/pkg/config"
+)
+
+type Applier interface {
+	// ApplyManifest does applying the given manifest.
+	ApplyManifest(ctx context.Context, manifest Manifest) error
+	// CreateManifest does creating resource from given manifest.
+	CreateManifest(ctx context.Context, manifest Manifest) error
+	// ReplaceManifest does replacing resource from given manifest.
+	ReplaceManifest(ctx context.Context, manifest Manifest) error
+	// Delete deletes the given resource from Kubernetes cluster.
+	Delete(ctx context.Context, key ResourceKey) error
+}
+
+type applier struct {
+	input  config.KubernetesDeploymentInput
+	logger *zap.Logger
+
+	kubectl  *Kubectl
+	initOnce sync.Once
+	initErr  error
+}
+
+func NewApplier(input config.KubernetesDeploymentInput, logger *zap.Logger) Applier {
+	return &applier{
+		input:  input,
+		logger: logger.Named("kubernetes-applier"),
+	}
+}
+
+// ApplyManifest does applying the given manifest.
+func (a *applier) ApplyManifest(ctx context.Context, manifest Manifest) error {
+	a.initOnce.Do(func() {
+		a.kubectl, a.initErr = a.findKubectl(ctx, a.input.KubectlVersion)
+	})
+	if a.initErr != nil {
+		return a.initErr
+	}
+
+	return a.kubectl.Apply(ctx, a.getNamespaceToRun(manifest.Key), manifest)
+}
+
+// CreateManifest uses kubectl to create the given manifests.
+func (a *applier) CreateManifest(ctx context.Context, manifest Manifest) error {
+	a.initOnce.Do(func() {
+		a.kubectl, a.initErr = a.findKubectl(ctx, a.input.KubectlVersion)
+	})
+	if a.initErr != nil {
+		return a.initErr
+	}
+
+	return a.kubectl.Create(ctx, a.getNamespaceToRun(manifest.Key), manifest)
+}
+
+// ReplaceManifest uses kubectl to replace the given manifests.
+func (a *applier) ReplaceManifest(ctx context.Context, manifest Manifest) error {
+	a.initOnce.Do(func() {
+		a.kubectl, a.initErr = a.findKubectl(ctx, a.input.KubectlVersion)
+	})
+	if a.initErr != nil {
+		return a.initErr
+	}
+
+	err := a.kubectl.Replace(ctx, a.getNamespaceToRun(manifest.Key), manifest)
+	if err == nil {
+		return nil
+	}
+
+	if errors.Is(err, errorReplaceNotFound) {
+		return ErrNotFound
+	}
+
+	return err
+}
+
+// Delete deletes the given resource from Kubernetes cluster.
+func (a *applier) Delete(ctx context.Context, k ResourceKey) (err error) {
+	a.initOnce.Do(func() {
+		a.kubectl, a.initErr = a.findKubectl(ctx, a.input.KubectlVersion)
+	})
+	if a.initErr != nil {
+		return a.initErr
+	}
+
+	return a.kubectl.Delete(ctx, a.getNamespaceToRun(k), k)
+}
+
+// getNamespaceToRun returns namespace used on kubectl apply/delete commands.
+// priority: config.KubernetesDeploymentInput > kubernetes.ResourceKey
+func (a *applier) getNamespaceToRun(k ResourceKey) string {
+	if a.input.Namespace != "" {
+		return a.input.Namespace
+	}
+	return k.Namespace
+}
+
+func (a *applier) findKubectl(ctx context.Context, version string) (*Kubectl, error) {
+	path, installed, err := toolregistry.DefaultRegistry().Kubectl(ctx, version)
+	if err != nil {
+		return nil, fmt.Errorf("no kubectl %s (%v)", version, err)
+	}
+	if installed {
+		a.logger.Info(fmt.Sprintf("kubectl %s has just been installed because of no pre-installed binary for that version", version))
+	}
+	return NewKubectl(version, path), nil
+}