feat: Support for config file reading (#55)

Author: jellonek

README.md

@@ -41,6 +41,22 @@ Use "cloudctl [command] --help" for more information about a command.
 ## Requirements and Setup
 Download the latest release from [here](https://github.com/cloudoperators/cloudctl/releases), move to a location in PATH and update file permissions.
 
+## Passing configuration options
+Configuration options for each command can be provided through command line parameters, environment variables (using `CLOUDCTL_` as a variable name prefix), and/or through configuration file.
+Configuration file location is searched in that order (first found takes precedence):
+* what is provided as a value for `--config` parameter
+* what is provided as a value for `$CLOUDCTL_CONFIG` environment variable
+* file paths:
+  * `./.cloudctl.yaml`
+  * `$HOME/.cloudctl.yaml`
+  * `./cloudctl.yaml`
+  * `$HOME/cloudctl.yaml`
+  * if `$XDG_CONFIG_HOME` is set:
+     * `$XDG_CONFIG_HOME/cloudctl/cloudctl.yaml`
+     * `$XDG_CONFIG_HOME/cloudctl.yaml`
+  * if not, finally falling back to:
+     * `$HOME/.config/cloudctl/cloudctl.yaml`
+     * `$HOME/.config/cloudctl.yaml`
 
 ## Support, Feedback, Contributing
 

cmd/cluster-version.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
 	"k8s.io/apimachinery/pkg/version"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
@@ -31,6 +32,9 @@ var (
 )
 
 func runClusterVersion(cmd *cobra.Command, args []string) error {
+	// Use viper as a source of configuration
+	kubeconfig = viper.GetString("kubeconfig")
+	kubecontext = viper.GetString("context")
 
 	cfg, err := configWithContext(kubecontext, kubeconfig)
 	if err != nil {
@@ -138,4 +142,9 @@ func getUnauthenticatedVersion(cfg *rest.Config) (*version.Info, error) {
 func init() {
 	clusterVersionCmd.Flags().StringVarP(&kubeconfig, "kubeconfig", "k", clientcmd.RecommendedHomeFile, "kubeconfig file path")
 	clusterVersionCmd.Flags().StringVarP(&kubecontext, "context", "c", "", "cluster version of the specified context in kubeconfig")
+
+	// BindPFlags can theroretically return an error if called with `nil` as an argument
+	// which should never happened after at least one flag was defined. That's why the output
+	// there is ignored.
+	viper.BindPFlags(clusterVersionCmd.Flags())
 }

cmd/root.go

@@ -5,8 +5,12 @@ package cmd
 
 import (
 	"context"
+	"os"
+	"path/filepath"
 
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
 )
@@ -32,12 +36,26 @@ Examples:
       cloudctl version`,
 }
 
+var (
+	configFilePath string
+)
+
 // Execute runs the CLI with the provided context.
 func Execute(ctx context.Context) error {
 	return rootCmd.ExecuteContext(ctx)
 }
 
 func init() {
+	cobra.OnInitialize(func() {
+		cobra.CheckErr(setupConfig())
+	})
+	rootCmd.PersistentFlags().StringVar(&configFilePath, "config", "", "Path to configuration file")
+
+	// BindPFlags can theroretically return an error if called with `nil` as an argument
+	// which should never happened after at least one flag was defined. That's why the output
+	// there is ignored.
+	viper.BindPFlags(rootCmd.PersistentFlags())
+
 	// Add subcommands here
 	rootCmd.AddCommand(syncCmd)
 	rootCmd.AddCommand(clusterVersionCmd)
@@ -55,3 +73,64 @@ func configWithContext(contextName, kubeconfigPath string) (*rest.Config, error)
 	cc := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules, overrides)
 	return cc.ClientConfig()
 }
+
+func setupConfig() error {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return err
+	}
+
+	// Optionally read environment variables, config files, etc.
+	viper.SetEnvPrefix("CLOUDCTL")
+	viper.AutomaticEnv()
+
+	viper.SetConfigType("yaml")
+
+	configFilePath = viper.GetString("config")
+	if len(configFilePath) > 0 {
+		// Phase 1
+		// First we are trying config provided as a command line parameter. Fail if there was an error
+		// during reading configuration from this specified path.
+		viper.SetConfigFile(configFilePath)
+		return viper.ReadInConfig()
+	} else {
+		// Phase 2
+		// Then we are searching for ".cloudctl.yaml" in current or home directory
+		viper.AddConfigPath(".")
+		viper.AddConfigPath(home)
+		// NOTE: viper is automatically adding a file extension basing on the value of called above `SetConfigType`
+		viper.SetConfigName(".cloudctl")
+	}
+
+	err = viper.ReadInConfig()
+	if _, ok := err.(viper.ConfigFileNotFoundError); ok {
+		// Phase 3
+		// If reading config in above described locations failed, we are looking for configuration
+		// in these locations:
+		//   locations set in PHASE 2:
+		//     ./cloudctl.yaml
+		//     $HOME/cloudctl.yaml
+		//   if $XDG_CONFIG_HOME is set:
+		//     $XDG_CONFIG_HOME/cloudctl/cloudctl.yaml
+		//     $XDG_CONFIG_HOME/cloudctl.yaml
+		//   else:
+		//     $HOME/.config/cloudctl/cloudctl.yaml
+		//     $HOME/.config/cloudctl.yaml
+		// NOTE: viper is automatically adding a file extension basing on the value of called above `SetConfigType`
+		viper.SetConfigName("cloudctl")
+		if xdgConfig := os.Getenv("XDG_CONFIG_HOME"); len(xdgConfig) > 0 {
+			viper.AddConfigPath(filepath.Join(xdgConfig, "cloudctl"))
+			viper.AddConfigPath(xdgConfig)
+		} else {
+			viper.AddConfigPath(filepath.Join(home, ".config", "cloudctl"))
+			viper.AddConfigPath(filepath.Join(home, ".config"))
+		}
+		err = viper.ReadInConfig()
+		// If configuration was not found in any of above listed locations - that's ok.
+		if _, ok := err.(viper.ConfigFileNotFoundError); ok {
+			err = nil
+		}
+	}
+
+	return err
+}

cmd/root_test.go

@@ -0,0 +1,79 @@
+// SPDX-FileCopyrightText: 2024 SAP SE or an SAP affiliate company and Greenhouse contributors
+// SPDX-License-Identifier: Apache-2.0
+
+package cmd
+
+import (
+	"os"
+	"testing"
+
+	"github.com/spf13/viper"
+
+	. "github.com/onsi/gomega"
+)
+
+var ConfigA = []byte(`kubeconfig: A
+config: B
+`)
+
+func TestNotSetConfigPath(t *testing.T) {
+	g := NewWithT(t)
+
+	t.Cleanup(func() { viper.Reset() })
+
+	// Ensure default config file location is not set
+	config := rootCmd.PersistentFlags().Lookup("config")
+	g.Expect(config).NotTo(BeNil())
+	g.Expect(config.Value.String()).To(BeEmpty())
+
+	// ... and that does not lead to an error during configuration setup
+	g.Expect(setupConfig()).To(BeNil())
+}
+
+func TestConfigurationLoad(t *testing.T) {
+	g := NewWithT(t)
+
+	f, err := os.CreateTemp("", "test_cloudctl_config")
+	g.Expect(err).To(BeNil())
+	t.Cleanup(func() { os.Remove(f.Name()) })
+
+	_, err = f.Write(ConfigA)
+	g.Expect(err).To(BeNil())
+	err = f.Close()
+	g.Expect(err).To(BeNil())
+
+	// Set config file location env variable
+	orig := os.Getenv("CLOUDCTL_CONFIG")
+	os.Setenv("CLOUDCTL_CONFIG", f.Name())
+
+	t.Cleanup(func() {
+		viper.Reset()
+		os.Setenv("CLOUDCTL_CONFIG", orig)
+	})
+
+	// Do the setup
+	g.Expect(setupConfig()).To(BeNil())
+
+	// Check if config file variable was not overwriten with data from config file
+	g.Expect(viper.GetString("config")).To(Equal(f.Name()))
+
+	// Check if `kubeconfig` variable was set to the value from temporary file
+	g.Expect(viper.GetString("kubeconfig")).To(Equal("A"))
+}
+
+func TestMissingConfigurationFile(t *testing.T) {
+	g := NewWithT(t)
+
+	// Set config file location env variable
+	orig := os.Getenv("CLOUDCTL_CONFIG")
+	os.Setenv("CLOUDCTL_CONFIG", "A")
+
+	t.Cleanup(func() {
+		viper.Reset()
+		os.Setenv("CLOUDCTL_CONFIG", orig)
+	})
+
+	// Do the setup
+	err := setupConfig()
+	g.Expect(err).NotTo(BeNil())
+}

cmd/sync.go

@@ -18,6 +18,7 @@ import (
 	greenhousemetav1alpha1 "github.com/cloudoperators/greenhouse/api/meta/v1alpha1"
 	"github.com/cloudoperators/greenhouse/api/v1alpha1"
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
@@ -56,6 +57,11 @@ func init() {
 	syncCmd.Flags().StringVar(&kubeloginPath, "kubelogin-path", "kubelogin", "path to kubelogin command when using exec-plugin auth-type")
 	syncCmd.Flags().StringSliceVar(&kubeloginExtraArgs, "kubelogin-extra-args", nil, "extra arguments to pass to kubelogin exec plugin")
 	syncCmd.Flags().StringVar(&kubeloginTokenCacheDir, "kubelogin-token-cache-dir", "$(HOME)/.kube/cache/oidc-login", "token cache directory for kubelogin")
+
+	// BindPFlags can theroretically return an error if called with `nil` as an argument
+	// which should never happened after at least one flag was defined. That's why the output
+	// there is ignored.
+	viper.BindPFlags(syncCmd.Flags())
 }
 
 var syncCmd = &cobra.Command{
@@ -65,6 +71,19 @@ var syncCmd = &cobra.Command{
 }
 
 func runSync(cmd *cobra.Command, args []string) error {
+	// Use viper as a source of configuration
+	greenhouseClusterKubeconfig = viper.GetString("greenhouse-cluster-kubeconfig")
+	greenhouseClusterContext = viper.GetString("greenhouse-cluster-context")
+	greenhouseClusterNamespace = viper.GetString("greenhouse-cluster-namespace")
+	remoteClusterKubeconfig = viper.GetString("remote-cluster-kubeconfig")
+	remoteClusterName = viper.GetString("remote-cluster-name")
+	prefix = viper.GetString("prefix")
+	mergeIdenticalUsers = viper.GetBool("merge-identical-users")
+	authType = viper.GetString("auth-type")
+	kubeloginPath = viper.GetString("kubelogin-path")
+	kubeloginExtraArgs = viper.GetStringSlice("kubelogin-extra-args")
+	kubeloginTokenCacheDir = viper.GetString("kubelogin-token-cache-dir")
+
 	if greenhouseClusterKubeconfig == "" {
 		return fmt.Errorf("greenhouse cluster kubeconfig path is empty")
 	}

cmd/version.go

@@ -9,6 +9,7 @@ import (
 	"runtime"
 
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
 )
 
 var (
@@ -28,11 +29,6 @@ type versionInfo struct {
 	Platform  string `json:"platform"`
 }
 
-var (
-	versionShort bool
-	versionJSON  bool
-)
-
 var versionCmd = &cobra.Command{
 	Use:   "version",
 	Short: "Print the cloudctl version information",
@@ -46,7 +42,7 @@ var versionCmd = &cobra.Command{
 			Platform:  fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH),
 		}
 
-		if versionJSON {
+		if viper.GetBool("json") {
 			b, err := json.MarshalIndent(info, "", "  ")
 			if err != nil {
 				return err
@@ -55,7 +51,7 @@ var versionCmd = &cobra.Command{
 			return nil
 		}
 
-		if versionShort {
+		if viper.GetBool("short") {
 			fmt.Println(info.Version)
 			return nil
 		}
@@ -69,6 +65,11 @@ var versionCmd = &cobra.Command{
 }
 
 func init() {
-	versionCmd.Flags().BoolVar(&versionShort, "short", false, "print only the version number")
-	versionCmd.Flags().BoolVar(&versionJSON, "json", false, "print version information as JSON")
+	versionCmd.Flags().Bool("short", false, "print only the version number")
+	versionCmd.Flags().Bool("json", false, "print version information as JSON")
+
+	// BindPFlags can theroretically return an error if called with `nil` as an argument
+	// which should never happened after at least one flag was defined. That's why the output
+	// there is ignored.
+	viper.BindPFlags(versionCmd.Flags())
 }

main.go

@@ -10,18 +10,12 @@ import (
 	"os/signal"
 	"syscall"
 
-	"github.com/spf13/viper"
-
 	"github.com/cloudoperators/cloudctl/cmd"
 
 	_ "k8s.io/client-go/plugin/pkg/client/auth/oidc"
 )
 
 func main() {
-	// Optionally read environment variables, config files, etc.
-	viper.SetEnvPrefix("CLOUDCTL")
-	viper.AutomaticEnv()
-
 	// Graceful cancellation on SIGINT/SIGTERM
 	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
 	defer stop()