Agent skill

cobra-scaffolder

Generate Cobra/Viper-based Go CLI applications with persistent flags, subcommands, and configuration management. Creates production-ready Go CLI with modern patterns.

View SKILL.md on GitHub Repository
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Forks 31

Install this agent skill to your Project

npx add-skill https://github.com/a5c-ai/babysitter/tree/main/library/specializations/cli-mcp-development/skills/cobra-scaffolder

SKILL.md

Cobra Scaffolder

Generate a complete Cobra CLI application with Viper configuration, proper Go module structure, and best practices.

Capabilities

  • Generate Go-based Cobra CLI projects
  • Create command hierarchy with persistent and local flags
  • Integrate Viper for configuration management
  • Set up automatic environment variable binding
  • Implement shell completion generation
  • Configure go.mod and build workflows

Usage

Invoke this skill when you need to:

  • Bootstrap a new CLI application using Cobra
  • Create a Go CLI with hierarchical commands
  • Integrate Viper for multi-source configuration
  • Build cross-platform native binaries

Inputs

Parameter Type Required Description
projectName string Yes Name of the CLI project (kebab-case)
modulePath string Yes Go module path (e.g., github.com/user/project)
description string Yes Short description of the CLI
commands array No List of commands to scaffold
useViper boolean No Integrate Viper config (default: true)
useCobra boolean No Use cobra-cli generator patterns (default: true)

Command Structure

json
{
  "commands": [
    {
      "name": "serve",
      "description": "Start the server",
      "persistentFlags": [
        { "name": "config", "shorthand": "c", "type": "string", "usage": "config file path" }
      ],
      "flags": [
        { "name": "port", "shorthand": "p", "type": "int", "default": 8080, "usage": "port to listen on" }
      ],
      "subcommands": ["start", "stop", "status"]
    }
  ]
}

Output Structure

<projectName>/
├── go.mod
├── go.sum
├── main.go
├── README.md
├── .goreleaser.yaml
├── cmd/
│   ├── root.go              # Root command with Viper
│   ├── serve.go             # Serve command
│   ├── version.go           # Version command
│   └── completion.go        # Completion command
├── internal/
│   ├── config/
│   │   └── config.go        # Configuration structures
│   ├── server/
│   │   └── server.go        # Server implementation
│   └── logger/
│       └── logger.go        # Logging setup
├── pkg/
│   └── utils/
│       └── helpers.go       # Public utilities
└── tests/
    └── cmd/
        └── root_test.go

Generated Code Patterns

Root Command (cmd/root.go)

go
package cmd

import (
    "fmt"
    "os"

    "github.com/spf13/cobra"
    "github.com/spf13/viper"
)

var cfgFile string

var rootCmd = &cobra.Command{
    Use:   "<projectName>",
    Short: "<description>",
    Long:  `<long description>`,
    PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
        return initConfig()
    },
}

func Execute() {
    if err := rootCmd.Execute(); err != nil {
        fmt.Fprintln(os.Stderr, err)
        os.Exit(1)
    }
}

func init() {
    rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "",
        "config file (default is $HOME/.<projectName>.yaml)")
    rootCmd.PersistentFlags().BoolP("verbose", "v", false, "verbose output")

    viper.BindPFlag("verbose", rootCmd.PersistentFlags().Lookup("verbose"))
}

func initConfig() error {
    if cfgFile != "" {
        viper.SetConfigFile(cfgFile)
    } else {
        home, err := os.UserHomeDir()
        cobra.CheckErr(err)

        viper.AddConfigPath(home)
        viper.SetConfigType("yaml")
        viper.SetConfigName(".<projectName>")
    }

    viper.AutomaticEnv()
    viper.SetEnvPrefix("<PROJECT_NAME>")

    if err := viper.ReadInConfig(); err == nil {
        fmt.Fprintln(os.Stderr, "Using config file:", viper.ConfigFileUsed())
    }
    return nil
}

Command Template (cmd/serve.go)

go
package cmd

import (
    "fmt"

    "github.com/spf13/cobra"
    "github.com/spf13/viper"
)

var serveCmd = &cobra.Command{
    Use:   "serve",
    Short: "Start the server",
    Long:  `Start the server with the specified configuration.`,
    RunE: func(cmd *cobra.Command, args []string) error {
        port := viper.GetInt("port")
        host := viper.GetString("host")

        fmt.Printf("Starting server on %s:%d\n", host, port)
        return nil
    },
}

func init() {
    rootCmd.AddCommand(serveCmd)

    serveCmd.Flags().IntP("port", "p", 8080, "port to listen on")
    serveCmd.Flags().String("host", "localhost", "host to bind to")

    viper.BindPFlag("port", serveCmd.Flags().Lookup("port"))
    viper.BindPFlag("host", serveCmd.Flags().Lookup("host"))
}

Dependencies

go
module github.com/user/<projectName>

go 1.21

require (
    github.com/spf13/cobra v1.8.0
    github.com/spf13/viper v1.18.0
)

Workflow

  1. Validate inputs - Check project name, module path
  2. Create directory structure - Set up Go project layout
  3. Generate go.mod - Configure module and dependencies
  4. Create root command - Viper integration and global flags
  5. Generate commands - Individual command files
  6. Create internal packages - Config, logger, etc.
  7. Set up goreleaser - Cross-platform build config
  8. Create tests - Command tests with cobra testing

Best Practices Applied

  • Standard Go project layout
  • Viper for configuration management
  • Persistent flags for shared options
  • Environment variable binding
  • Built-in completion generation
  • Goreleaser for distribution

References

Target Processes

  • cli-application-bootstrap
  • cli-command-structure-design
  • configuration-management-system

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