cobra

cobra包是一个指挥官，提供了一个简单的接口来创建强大的现代CLI接口。除了提供接口之外，Cobra还提供了一个控制器来组织应用程序代码。
文档：https://godoc.org/github.com/spf13/cobra

type Command

type Command struct {
    // Use是一行用法消息，rootcmd 可以忽略它
    Use string
    // 别名是一个别名数组，可以用来代替使用的第一个单词
    Aliases []string
    // Short是在“help”输出中显示的简短描述
    Short string
    // Long是'help <this-command>'输出中显示的长消息
    Long string
    // Example 是显示如何使用命令
    Example string
    // ValidArgs is list of all valid non-flag arguments that are accepted in bash completions
    ValidArgs []string
    // ValidArgsFunction is an optional function that provides valid non-flag arguments for bash completion.
    // It is a dynamic version of using ValidArgs.
    // Only one of ValidArgs and ValidArgsFunction can be used for a command.
    ValidArgsFunction func(cmd *Command, args []string, toComplete string) ([]string, ShellCompDirective)
    // 所有参数
    Args PositionalArgs
    // ArgAliases is List of aliases for ValidArgs.
    // These are not suggested to the user in the bash completion,
    // but accepted if entered manually.
    ArgAliases []string
    // BashCompletionFunction is custom functions used by the bash autocompletion generator.
    BashCompletionFunction string
    // Deprecated defines, if this command is deprecated and should print this string when used.
    Deprecated string
    // Hidden defines, if this command is hidden and should NOT show up in the list of available commands.
    Hidden bool
    // Annotations are key/value pairs that can be used by applications to identify or
    // group commands.
    Annotations map[string]string
    // 定义一个version标识，可通过 version 或 -v 查看
    Version string
    //   Run函数按以下顺序执行:
    //   * PersistentPreRun()
    //   * PreRun()
    //   * Run()
    //   * PostRun()
    //   * PersistentPostRun()
    // 所有函数都得到相同的参数，即命令名后面的参数.
    //
    // PersistentPreRun: children of this command will inherit and execute.
    PersistentPreRun func(cmd *Command, args []string)
    // PersistentPreRunE: PersistentPreRun but returns an error.
    PersistentPreRunE func(cmd *Command, args []string) error
    // PreRun: children of this command will not inherit.
    PreRun func(cmd *Command, args []string)
    // PreRunE: PreRun but returns an error.
    PreRunE func(cmd *Command, args []string) error
    // Run: Typically the actual work function. Most commands will only implement this.
    Run func(cmd *Command, args []string)
    // RunE: Run but returns an error.
    RunE func(cmd *Command, args []string) error
    // PostRun: run after the Run command.
    PostRun func(cmd *Command, args []string)
    // PostRunE: PostRun but returns an error.
    PostRunE func(cmd *Command, args []string) error
    // PersistentPostRun: children of this command will inherit and execute after PostRun.
    PersistentPostRun func(cmd *Command, args []string)
    // PersistentPostRunE: PersistentPostRun but returns an error.
    PersistentPostRunE func(cmd *Command, args []string) error
    // 对下游的错误进行屏蔽
    SilenceErrors bool
    // 对错误用法进行屏蔽
    SilenceUsage bool
    // 禁用标志解析.
    // 如果为真，所有标志都将作为参数传递给该命令
    DisableFlagParsing bool
    // DisableAutoGenTag defines, if gen tag ("Auto generated by spf13/cobra...")
    // will be printed by generating docs for this command.
    DisableAutoGenTag bool
    // DisableFlagsInUseLine will disable the addition of [flags] to the usage
    // line of a command when printing help or generating docs
    DisableFlagsInUseLine bool
    // DisableSuggestions disables the suggestions based on Levenshtein distance
    // that go along with 'unknown command' messages.
    DisableSuggestions bool
    // SuggestionsMinimumDistance defines minimum levenshtein distance to display suggestions.
    // Must be > 0.
    SuggestionsMinimumDistance int
    // TraverseChildren parses flags on all parents before executing child command.
    TraverseChildren bool
    // FParseErrWhitelist flag parse errors to be ignored
    FParseErrWhitelist FParseErrWhitelist
    // contains filtered or unexported fields
}

func (c Command) AddCommand(cmds …Command) 向父命令添加一个或多个命令
func (c Command) PersistentFlags() flag.FlagSet PersistentFlags返回在当前命令中特定设置的持久标记集
func (c *Command) Execute() error

• 使用args (os.Args[1:] by default)，遍历命令树，找到命令的适当匹配项，然后找到相应的标志。

type PositionalArgs

type PositionalArgs func(cmd *Command, args []string) error

例子

package main
import (
    "fmt"
    "os"
    "github.com/spf13/cobra"
)
// rootCmd.PersistentFlags() 中设置的参数，将被标记为 Global Flags
var rootCmd = &cobra.Command{
    Short:   "opct server",
    Long:    "opct server",
    Version: "v1.0",
    Args: func(cmd *cobra.Command, args []string) error {
        if len(args) < 1 {
            return errors.New("requires at least one arg")
        }
        return nil
    },
    PersistentPreRunE: func(*cobra.Command, []string) error { return nil },
    Run: func(cmd *cobra.Command, args []string) {
        usageStr := `欢迎使用 四格自动化运维平台，可以使用 -h 查看命令`
        fmt.Println(usageStr)
    },
}
var (
    config      string
    casbinModel string
    StartCmd    = &cobra.Command{
        Use:     "start",
        Short:   "Start API server",
        Example: "OPCT server -c config/settings.yml -m config/casbin_model.conf",
        PreRun: func(cmd *cobra.Command, args []string) {
            // 初始化项目配置
            setup()
        },
        RunE: func(cmd *cobra.Command, args []string) error {
            return start()
        },
    }
    StartCmd2 = &cobra.Command{
        Use:     "start2",
        Short:   "Start2 API server",
        Example: "OPCT server -c config/settings.yml -m config/casbin_model.conf",
        PreRun: func(cmd *cobra.Command, args []string) {
            // 初始化项目配置
            setup()
        },
        RunE: func(cmd *cobra.Command, args []string) error {
            return start2()
        },
    }
)
func init() {
    rootCmd.AddCommand(StartCmd) // rootCmd 增加子命令行
    StartCmd.AddCommand(StartCmd2)
    // StartCmd 增加命令行参数
    StartCmd.PersistentFlags().StringVarP(&config, "config", "c", "config/app.toml", "Start server with provided configuration file")
    StartCmd.PersistentFlags().StringVarP(&casbinModel, "casbinmodel", "m", "config/casbin_model.conf", "Start server with provided casbinmodel file")
}
func main() {
    if err := rootCmd.Execute(); err != nil {
        os.Exit(-1)
    }
}
func setup() {
    // 在start()之前运行，用作初始化项目
}
func start() error {
    fmt.Println(config)
    fmt.Println(casbinModel)
    return nil
}
func start2() error {
    fmt.Println("-------------------")
    return nil
}

二级及更低等级命名的执行，必须带上它父级与更高级的执行命令