[RFC-007] Flux cmd support for GitHub provider: This commit includes the following changes -

- Add flux create secret githubapp command that accepts and validates the inputs to create a github app secret with options to export the secret yaml or create the secret directly in the Kubernetes cluster

- Add tests for flux create secret githubapp command

- Add flux create source git command that accepts and validates the inputs to create a gitrepository source with for github provider with options to export the source yaml or create the github gitrepository source directly in the Kubernetes cluster.

- Add tests for flux create source git command for github provider.

Signed-off-by: Dipti Pai <diptipai89@outlook.com>

cmd/flux/create_secret_github_app.go

@@ -0,0 +1,128 @@
+/*
+Copyright 2024 The Flux 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 main
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"github.com/fluxcd/flux2/v2/internal/utils"
+	"github.com/fluxcd/flux2/v2/pkg/manifestgen/sourcesecret"
+	"github.com/spf13/cobra"
+	corev1 "k8s.io/api/core/v1"
+	"sigs.k8s.io/yaml"
+)
+
+var createSecretGitHubAppCmd = &cobra.Command{
+	Use:   "githubapp [name]",
+	Short: "Create or update a github app secret",
+	Long:  withPreviewNote(`The create secret githubapp command generates a Kubernetes secret that can be used for GitRepository authentication with github app`),
+	Example: `  # Create a githubapp authentication secret on disk and encrypt it with Mozilla SOPS
+  flux create secret githubapp podinfo-auth \
+    --app-id="1" \
+    --app-installation-id="2" \
+    --app-private-key=./private-key-file.pem \
+    --export > githubapp-auth.yaml
+
+  sops --encrypt --encrypted-regex '^(data|stringData)$' \
+    --in-place githubapp-auth.yaml
+	`,
+	RunE: createSecretGitHubAppCmdRun,
+}
+
+type secretGitHubAppFlags struct {
+	appID             string
+	appInstallationID string
+	privateKeyFile    string
+	baseURL           string
+}
+
+var secretGitHubAppArgs = secretGitHubAppFlags{}
+
+func init() {
+	createSecretGitHubAppCmd.Flags().StringVar(&secretGitHubAppArgs.appID, "app-id", "", "github app ID")
+	createSecretGitHubAppCmd.Flags().StringVar(&secretGitHubAppArgs.appInstallationID, "app-installation-id", "", "github app installation ID")
+	createSecretGitHubAppCmd.Flags().StringVar(&secretGitHubAppArgs.privateKeyFile, "app-private-key", "", "github app private key file path")
+	createSecretGitHubAppCmd.Flags().StringVar(&secretGitHubAppArgs.baseURL, "app-base-url", "", "github app base URL")
+
+	createSecretCmd.AddCommand(createSecretGitHubAppCmd)
+}
+
+func createSecretGitHubAppCmdRun(cmd *cobra.Command, args []string) error {
+	if len(args) < 1 {
+		return fmt.Errorf("name is required")
+	}
+
+	secretName := args[0]
+
+	if secretGitHubAppArgs.appID == "" {
+		return fmt.Errorf("--app-id is required")
+	}
+
+	if secretGitHubAppArgs.appInstallationID == "" {
+		return fmt.Errorf("--app-installation-id is required")
+	}
+
+	if secretGitHubAppArgs.privateKeyFile == "" {
+		return fmt.Errorf("--app-private-key is required")
+	}
+
+	privateKey, err := os.ReadFile(secretGitHubAppArgs.privateKeyFile)
+	if err != nil {
+		return fmt.Errorf("unable to read private key file: %w", err)
+	}
+
+	opts := sourcesecret.Options{
+		Name:                    secretName,
+		Namespace:               *kubeconfigArgs.Namespace,
+		GitHubAppID:             secretGitHubAppArgs.appID,
+		GitHubAppInstallationID: secretGitHubAppArgs.appInstallationID,
+		GitHubAppPrivateKey:     string(privateKey),
+	}
+
+	if secretGitHubAppArgs.baseURL != "" {
+		opts.GitHubAppBaseURL = secretGitHubAppArgs.baseURL
+	}
+
+	secret, err := sourcesecret.Generate(opts)
+	if err != nil {
+		return err
+	}
+
+	if createArgs.export {
+		rootCmd.Println(secret.Content)
+		return nil
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), rootArgs.timeout)
+	defer cancel()
+	kubeClient, err := utils.KubeClient(kubeconfigArgs, kubeclientOptions)
+	if err != nil {
+		return err
+	}
+	var s corev1.Secret
+	if err := yaml.Unmarshal([]byte(secret.Content), &s); err != nil {
+		return err
+	}
+	if err := upsertSecret(ctx, kubeClient, s); err != nil {
+		return err
+	}
+
+	logger.Actionf("githubapp secret '%s' created in '%s' namespace", secretName, *kubeconfigArgs.Namespace)
+	return nil
+}