Initial commit
This commit is contained in:
Zhongwei Li
538
skills/cobra-patterns/examples/production-cli-complete.md
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538
skills/cobra-patterns/examples/production-cli-complete.md
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# Complete Production CLI Example
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A complete example demonstrating all production features: configuration management, error handling, logging, context support, and testing.
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## Features
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- ✅ Viper configuration management
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- ✅ Structured logging (with levels)
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- ✅ Context-aware commands (cancellation support)
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- ✅ Proper error handling with wrapped errors
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- ✅ Shell completion
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- ✅ Unit and integration tests
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- ✅ Dry-run support
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- ✅ Multiple output formats
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- ✅ Version information
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- ✅ Configuration file support
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## Complete Implementation
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### main.go
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```go
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package main
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import (
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"context"
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"os"
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"os/signal"
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"syscall"
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"github.com/example/myapp/cmd"
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)
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func main() {
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// Setup context with cancellation
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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// Handle interrupt signals gracefully
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sigChan := make(chan os.Signal, 1)
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signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)
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go func() {
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<-sigChan
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cancel()
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}()
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// Execute with context
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if err := cmd.ExecuteContext(ctx); err != nil {
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os.Exit(1)
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}
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}
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```
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### cmd/root.go
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```go
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package cmd
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import (
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"context"
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"fmt"
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"os"
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"github.com/spf13/cobra"
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"github.com/spf13/viper"
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"go.uber.org/zap"
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"go.uber.org/zap/zapcore"
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)
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var (
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cfgFile string
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verbose bool
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logLevel string
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logger *zap.Logger
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)
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var rootCmd = &cobra.Command{
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Use: "myapp",
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Short: "A production-grade CLI application",
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Long: `A complete production CLI with proper error handling,
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configuration management, logging, and context support.`,
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Version: "1.0.0",
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PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
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// Initialize logger based on flags
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return initLogger()
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},
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}
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func ExecuteContext(ctx context.Context) error {
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rootCmd.SetContext(ctx)
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return rootCmd.Execute()
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}
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func Execute() error {
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return rootCmd.Execute()
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}
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func init() {
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cobra.OnInitialize(initConfig)
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// Global flags
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rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.myapp.yaml)")
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rootCmd.PersistentFlags().BoolVarP(&verbose, "verbose", "v", false, "verbose output")
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rootCmd.PersistentFlags().StringVar(&logLevel, "log-level", "info", "log level (debug|info|warn|error)")
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// Bind to viper
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viper.BindPFlag("verbose", rootCmd.PersistentFlags().Lookup("verbose"))
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viper.BindPFlag("log-level", rootCmd.PersistentFlags().Lookup("log-level"))
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}
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func initConfig() {
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if cfgFile != "" {
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viper.SetConfigFile(cfgFile)
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} else {
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home, err := os.UserHomeDir()
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cobra.CheckErr(err)
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viper.AddConfigPath(home)
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viper.AddConfigPath(".")
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viper.SetConfigType("yaml")
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viper.SetConfigName(".myapp")
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}
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viper.AutomaticEnv()
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if err := viper.ReadInConfig(); err == nil && verbose {
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fmt.Fprintln(os.Stderr, "Using config file:", viper.ConfigFileUsed())
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}
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}
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func initLogger() error {
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// Parse log level
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level := zapcore.InfoLevel
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if err := level.UnmarshalText([]byte(logLevel)); err != nil {
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return fmt.Errorf("invalid log level: %w", err)
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}
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// Create logger config
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config := zap.NewProductionConfig()
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config.Level = zap.NewAtomicLevelAt(level)
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if verbose {
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config = zap.NewDevelopmentConfig()
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}
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// Build logger
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var err error
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logger, err = config.Build()
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if err != nil {
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return fmt.Errorf("failed to initialize logger: %w", err)
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}
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return nil
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}
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func GetLogger() *zap.Logger {
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if logger == nil {
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// Fallback logger
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logger, _ = zap.NewProduction()
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}
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return logger
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}
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```
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### cmd/process.go (Context-Aware Command)
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```go
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package cmd
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import (
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"context"
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"fmt"
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"time"
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"github.com/spf13/cobra"
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)
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var (
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processTimeout time.Duration
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processDryRun bool
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processWorkers int
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)
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var processCmd = &cobra.Command{
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Use: "process [files...]",
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Short: "Process files with context support",
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Long: `Process files with proper context handling,
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graceful cancellation, and timeout support.`,
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Args: cobra.MinimumNArgs(1),
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RunE: func(cmd *cobra.Command, args []string) error {
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ctx := cmd.Context()
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logger := GetLogger()
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// Apply timeout if specified
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if processTimeout > 0 {
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var cancel context.CancelFunc
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ctx, cancel = context.WithTimeout(ctx, processTimeout)
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defer cancel()
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}
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logger.Info("Starting process",
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zap.Strings("files", args),
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zap.Int("workers", processWorkers),
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zap.Bool("dry-run", processDryRun))
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if processDryRun {
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logger.Info("Dry run mode - no changes will be made")
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return nil
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}
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// Process with context
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if err := processFiles(ctx, args, processWorkers); err != nil {
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logger.Error("Processing failed", zap.Error(err))
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return fmt.Errorf("process failed: %w", err)
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}
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logger.Info("Processing completed successfully")
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return nil
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},
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}
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func init() {
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rootCmd.AddCommand(processCmd)
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processCmd.Flags().DurationVar(&processTimeout, "timeout", 0, "processing timeout")
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processCmd.Flags().BoolVar(&processDryRun, "dry-run", false, "simulate without changes")
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processCmd.Flags().IntVarP(&processWorkers, "workers", "w", 4, "number of workers")
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}
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func processFiles(ctx context.Context, files []string, workers int) error {
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logger := GetLogger()
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for _, file := range files {
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// Check context cancellation
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select {
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case <-ctx.Done():
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return ctx.Err()
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default:
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}
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logger.Debug("Processing file", zap.String("file", file))
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// Simulate work
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if err := processFile(ctx, file); err != nil {
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return fmt.Errorf("failed to process %s: %w", file, err)
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}
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}
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return nil
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}
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func processFile(ctx context.Context, file string) error {
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// Simulate processing with context awareness
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ticker := time.NewTicker(100 * time.Millisecond)
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defer ticker.Stop()
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for i := 0; i < 10; i++ {
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select {
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case <-ctx.Done():
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return ctx.Err()
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case <-ticker.C:
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// Do work
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}
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}
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return nil
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}
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```
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### cmd/config.go (Configuration Management)
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```go
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package cmd
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import (
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"fmt"
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"github.com/spf13/cobra"
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"github.com/spf13/viper"
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)
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var configCmd = &cobra.Command{
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Use: "config",
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Short: "Manage configuration",
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}
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var configViewCmd = &cobra.Command{
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Use: "view",
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Short: "View current configuration",
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RunE: func(cmd *cobra.Command, args []string) error {
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settings := viper.AllSettings()
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fmt.Println("Current Configuration:")
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fmt.Println("=====================")
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for key, value := range settings {
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fmt.Printf("%s: %v\n", key, value)
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}
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return nil
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},
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}
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var configSetCmd = &cobra.Command{
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Use: "set KEY VALUE",
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Short: "Set configuration value",
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Args: cobra.ExactArgs(2),
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RunE: func(cmd *cobra.Command, args []string) error {
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key := args[0]
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value := args[1]
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viper.Set(key, value)
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if err := viper.WriteConfig(); err != nil {
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if err := viper.SafeWriteConfig(); err != nil {
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return fmt.Errorf("failed to write config: %w", err)
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}
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}
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fmt.Printf("Set %s = %s\n", key, value)
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return nil
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},
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}
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func init() {
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rootCmd.AddCommand(configCmd)
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configCmd.AddCommand(configViewCmd)
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configCmd.AddCommand(configSetCmd)
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}
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```
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### cmd/version.go
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```go
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package cmd
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import (
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"fmt"
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"runtime"
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"github.com/spf13/cobra"
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)
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var (
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Version = "dev"
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Commit = "none"
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BuildTime = "unknown"
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)
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var versionCmd = &cobra.Command{
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Use: "version",
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Short: "Print version information",
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Run: func(cmd *cobra.Command, args []string) {
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fmt.Printf("myapp version %s\n", Version)
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fmt.Printf(" Commit: %s\n", Commit)
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fmt.Printf(" Built: %s\n", BuildTime)
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fmt.Printf(" Go version: %s\n", runtime.Version())
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fmt.Printf(" OS/Arch: %s/%s\n", runtime.GOOS, runtime.GOARCH)
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},
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}
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func init() {
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rootCmd.AddCommand(versionCmd)
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}
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```
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### Testing (cmd/root_test.go)
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```go
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package cmd
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import (
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"bytes"
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"context"
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"testing"
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"time"
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)
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func TestProcessCommand(t *testing.T) {
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// Reset command for testing
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processCmd.SetArgs([]string{"file1.txt", "file2.txt"})
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// Capture output
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buf := new(bytes.Buffer)
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processCmd.SetOut(buf)
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processCmd.SetErr(buf)
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// Execute
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err := processCmd.Execute()
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if err != nil {
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t.Errorf("Expected no error, got %v", err)
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}
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}
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func TestProcessCommandWithContext(t *testing.T) {
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ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
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defer cancel()
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processCmd.SetContext(ctx)
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processCmd.SetArgs([]string{"file1.txt"})
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err := processCmd.Execute()
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if err != nil {
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t.Errorf("Expected no error, got %v", err)
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}
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}
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func TestProcessCommandCancellation(t *testing.T) {
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ctx, cancel := context.WithCancel(context.Background())
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processCmd.SetContext(ctx)
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processCmd.SetArgs([]string{"file1.txt", "file2.txt"})
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// Cancel context immediately
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cancel()
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err := processCmd.Execute()
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if err == nil {
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t.Error("Expected context cancellation error")
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}
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}
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func TestConfigViewCommand(t *testing.T) {
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configViewCmd.SetArgs([]string{})
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buf := new(bytes.Buffer)
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configViewCmd.SetOut(buf)
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err := configViewCmd.Execute()
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if err != nil {
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t.Errorf("Expected no error, got %v", err)
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}
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output := buf.String()
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if output == "" {
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t.Error("Expected output, got empty string")
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}
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}
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```
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### Configuration File (.myapp.yaml)
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```yaml
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# Application configuration
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verbose: false
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log-level: info
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timeout: 30s
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# Custom settings
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api:
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endpoint: https://api.example.com
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timeout: 10s
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retries: 3
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database:
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host: localhost
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port: 5432
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name: myapp
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features:
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experimental: false
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beta: true
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```
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### Makefile
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```makefile
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VERSION := $(shell git describe --tags --always --dirty)
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COMMIT := $(shell git rev-parse HEAD)
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BUILD_TIME := $(shell date -u '+%Y-%m-%d_%H:%M:%S')
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LDFLAGS := -X github.com/example/myapp/cmd.Version=$(VERSION) \
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-X github.com/example/myapp/cmd.Commit=$(COMMIT) \
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-X github.com/example/myapp/cmd.BuildTime=$(BUILD_TIME)
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.PHONY: build
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build:
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go build -ldflags "$(LDFLAGS)" -o myapp
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.PHONY: test
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test:
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go test -v ./...
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.PHONY: coverage
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coverage:
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go test -coverprofile=coverage.out ./...
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go tool cover -html=coverage.out
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.PHONY: lint
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lint:
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golangci-lint run
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.PHONY: install
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install:
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go install -ldflags "$(LDFLAGS)"
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.PHONY: clean
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clean:
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rm -f myapp coverage.out
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```
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## Usage Examples
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```bash
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# Basic usage with verbose logging
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myapp process file.txt -v
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# With timeout and workers
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myapp process *.txt --timeout 30s --workers 8
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# Dry run
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myapp process file.txt --dry-run
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# Custom config file
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myapp --config prod.yaml process file.txt
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# View configuration
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myapp config view
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# Set configuration
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myapp config set api.timeout 15s
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# Version information
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myapp version
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# Shell completion
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myapp completion bash > /etc/bash_completion.d/myapp
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```
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## Key Patterns
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||||
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||||
1. **Context Awareness**: All long-running operations respect context cancellation
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||||
2. **Structured Logging**: Use zap for performance and structure
|
||||
3. **Configuration Management**: Viper for flexible config handling
|
||||
4. **Error Wrapping**: Use fmt.Errorf with %w for error chains
|
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5. **Testing**: Comprehensive unit and integration tests
|
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6. **Build Info**: Version, commit, and build time injection
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||||
|
||||
This example provides a complete production-ready CLI that you can use as a foundation for your own applications.
|
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Reference in New Issue
Block a user