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diff --git a/vendor/github.com/spf13/cobra/user_guide.md b/vendor/github.com/spf13/cobra/user_guide.md new file mode 100644 index 0000000000..e55367e853 --- /dev/null +++ b/vendor/github.com/spf13/cobra/user_guide.md @@ -0,0 +1,695 @@ +# User Guide + +While you are welcome to provide your own organization, typically a Cobra-based +application will follow the following organizational structure: + +``` + ▾ appName/ + ▾ cmd/ + add.go + your.go + commands.go + here.go + main.go +``` + +In a Cobra app, typically the main.go file is very bare. It serves one purpose: initializing Cobra. + +```go +package main + +import ( + "{pathToYourApp}/cmd" +) + +func main() { + cmd.Execute() +} +``` + +## Using the Cobra Generator + +Cobra-CLI is its own program that will create your application and add any +commands you want. It's the easiest way to incorporate Cobra into your application. + +For complete details on using the Cobra generator, please refer to [The Cobra-CLI Generator README](https://github.com/spf13/cobra-cli/blob/main/README.md) + +## Using the Cobra Library + +To manually implement Cobra you need to create a bare main.go file and a rootCmd file. +You will optionally provide additional commands as you see fit. + +### Create rootCmd + +Cobra doesn't require any special constructors. Simply create your commands. + +Ideally you place this in app/cmd/root.go: + +```go +var rootCmd = &cobra.Command{ + Use: "hugo", + Short: "Hugo is a very fast static site generator", + Long: `A Fast and Flexible Static Site Generator built with + love by spf13 and friends in Go. + Complete documentation is available at https://gohugo.io/documentation/`, + Run: func(cmd *cobra.Command, args []string) { + // Do Stuff Here + }, +} + +func Execute() { + if err := rootCmd.Execute(); err != nil { + fmt.Fprintln(os.Stderr, err) + os.Exit(1) + } +} +``` + +You will additionally define flags and handle configuration in your init() function. + +For example cmd/root.go: + +```go +package cmd + +import ( + "fmt" + "os" + + "github.com/spf13/cobra" + "github.com/spf13/viper" +) + +var ( + // Used for flags. + cfgFile string + userLicense string + + rootCmd = &cobra.Command{ + Use: "cobra-cli", + Short: "A generator for Cobra based Applications", + Long: `Cobra is a CLI library for Go that empowers applications. +This application is a tool to generate the needed files +to quickly create a Cobra application.`, + } +) + +// Execute executes the root command. +func Execute() error { + return rootCmd.Execute() +} + +func init() { + cobra.OnInitialize(initConfig) + + rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.cobra.yaml)") + rootCmd.PersistentFlags().StringP("author", "a", "YOUR NAME", "author name for copyright attribution") + rootCmd.PersistentFlags().StringVarP(&userLicense, "license", "l", "", "name of license for the project") + rootCmd.PersistentFlags().Bool("viper", true, "use Viper for configuration") + viper.BindPFlag("author", rootCmd.PersistentFlags().Lookup("author")) + viper.BindPFlag("useViper", rootCmd.PersistentFlags().Lookup("viper")) + viper.SetDefault("author", "NAME HERE <EMAIL ADDRESS>") + viper.SetDefault("license", "apache") + + rootCmd.AddCommand(addCmd) + rootCmd.AddCommand(initCmd) +} + +func initConfig() { + if cfgFile != "" { + // Use config file from the flag. + viper.SetConfigFile(cfgFile) + } else { + // Find home directory. + home, err := os.UserHomeDir() + cobra.CheckErr(err) + + // Search config in home directory with name ".cobra" (without extension). + viper.AddConfigPath(home) + viper.SetConfigType("yaml") + viper.SetConfigName(".cobra") + } + + viper.AutomaticEnv() + + if err := viper.ReadInConfig(); err == nil { + fmt.Println("Using config file:", viper.ConfigFileUsed()) + } +} +``` + +### Create your main.go + +With the root command you need to have your main function execute it. +Execute should be run on the root for clarity, though it can be called on any command. + +In a Cobra app, typically the main.go file is very bare. It serves one purpose: to initialize Cobra. + +```go +package main + +import ( + "{pathToYourApp}/cmd" +) + +func main() { + cmd.Execute() +} +``` + +### Create additional commands + +Additional commands can be defined and typically are each given their own file +inside of the cmd/ directory. + +If you wanted to create a version command you would create cmd/version.go and +populate it with the following: + +```go +package cmd + +import ( + "fmt" + + "github.com/spf13/cobra" +) + +func init() { + rootCmd.AddCommand(versionCmd) +} + +var versionCmd = &cobra.Command{ + Use: "version", + Short: "Print the version number of Hugo", + Long: `All software has versions. This is Hugo's`, + Run: func(cmd *cobra.Command, args []string) { + fmt.Println("Hugo Static Site Generator v0.9 -- HEAD") + }, +} +``` + +### Returning and handling errors + +If you wish to return an error to the caller of a command, `RunE` can be used. + +```go +package cmd + +import ( + "fmt" + + "github.com/spf13/cobra" +) + +func init() { + rootCmd.AddCommand(tryCmd) +} + +var tryCmd = &cobra.Command{ + Use: "try", + Short: "Try and possibly fail at something", + RunE: func(cmd *cobra.Command, args []string) error { + if err := someFunc(); err != nil { + return err + } + return nil + }, +} +``` + +The error can then be caught at the execute function call. + +## Working with Flags + +Flags provide modifiers to control how the action command operates. + +### Assign flags to a command + +Since the flags are defined and used in different locations, we need to +define a variable outside with the correct scope to assign the flag to +work with. + +```go +var Verbose bool +var Source string +``` + +There are two different approaches to assign a flag. + +### Persistent Flags + +A flag can be 'persistent', meaning that this flag will be available to the +command it's assigned to as well as every command under that command. For +global flags, assign a flag as a persistent flag on the root. + +```go +rootCmd.PersistentFlags().BoolVarP(&Verbose, "verbose", "v", false, "verbose output") +``` + +### Local Flags + +A flag can also be assigned locally, which will only apply to that specific command. + +```go +localCmd.Flags().StringVarP(&Source, "source", "s", "", "Source directory to read from") +``` + +### Local Flag on Parent Commands + +By default, Cobra only parses local flags on the target command, and any local flags on +parent commands are ignored. By enabling `Command.TraverseChildren`, Cobra will +parse local flags on each command before executing the target command. + +```go +command := cobra.Command{ + Use: "print [OPTIONS] [COMMANDS]", + TraverseChildren: true, +} +``` + +### Bind Flags with Config + +You can also bind your flags with [viper](https://github.com/spf13/viper): +```go +var author string + +func init() { + rootCmd.PersistentFlags().StringVar(&author, "author", "YOUR NAME", "Author name for copyright attribution") + viper.BindPFlag("author", rootCmd.PersistentFlags().Lookup("author")) +} +``` + +In this example, the persistent flag `author` is bound with `viper`. +**Note**: the variable `author` will not be set to the value from config, +when the `--author` flag is provided by user. + +More in [viper documentation](https://github.com/spf13/viper#working-with-flags). + +### Required flags + +Flags are optional by default. If instead you wish your command to report an error +when a flag has not been set, mark it as required: +```go +rootCmd.Flags().StringVarP(&Region, "region", "r", "", "AWS region (required)") +rootCmd.MarkFlagRequired("region") +``` + +Or, for persistent flags: +```go +rootCmd.PersistentFlags().StringVarP(&Region, "region", "r", "", "AWS region (required)") +rootCmd.MarkPersistentFlagRequired("region") +``` + +### Flag Groups + +If you have different flags that must be provided together (e.g. if they provide the `--username` flag they MUST provide the `--password` flag as well) then +Cobra can enforce that requirement: +```go +rootCmd.Flags().StringVarP(&u, "username", "u", "", "Username (required if password is set)") +rootCmd.Flags().StringVarP(&pw, "password", "p", "", "Password (required if username is set)") +rootCmd.MarkFlagsRequiredTogether("username", "password") +``` + +You can also prevent different flags from being provided together if they represent mutually +exclusive options such as specifying an output format as either `--json` or `--yaml` but never both: +```go +rootCmd.Flags().BoolVar(&u, "json", false, "Output in JSON") +rootCmd.Flags().BoolVar(&pw, "yaml", false, "Output in YAML") +rootCmd.MarkFlagsMutuallyExclusive("json", "yaml") +``` + +In both of these cases: + - both local and persistent flags can be used + - **NOTE:** the group is only enforced on commands where every flag is defined + - a flag may appear in multiple groups + - a group may contain any number of flags + +## Positional and Custom Arguments + +Validation of positional arguments can be specified using the `Args` field of `Command`. +The following validators are built in: + +- Number of arguments: + - `NoArgs` - report an error if there are any positional args. + - `ArbitraryArgs` - accept any number of args. + - `MinimumNArgs(int)` - report an error if less than N positional args are provided. + - `MaximumNArgs(int)` - report an error if more than N positional args are provided. + - `ExactArgs(int)` - report an error if there are not exactly N positional args. + - `RangeArgs(min, max)` - report an error if the number of args is not between `min` and `max`. +- Content of the arguments: + - `OnlyValidArgs` - report an error if there are any positional args not specified in the `ValidArgs` field of `Command`, which can optionally be set to a list of valid values for positional args. + +If `Args` is undefined or `nil`, it defaults to `ArbitraryArgs`. + +Moreover, `MatchAll(pargs ...PositionalArgs)` enables combining existing checks with arbitrary other checks. +For instance, if you want to report an error if there are not exactly N positional args OR if there are any positional +args that are not in the `ValidArgs` field of `Command`, you can call `MatchAll` on `ExactArgs` and `OnlyValidArgs`, as +shown below: + +```go +var cmd = &cobra.Command{ + Short: "hello", + Args: MatchAll(ExactArgs(2), OnlyValidArgs), + Run: func(cmd *cobra.Command, args []string) { + fmt.Println("Hello, World!") + }, +} +``` + +It is possible to set any custom validator that satisfies `func(cmd *cobra.Command, args []string) error`. +For example: + +```go +var cmd = &cobra.Command{ + Short: "hello", + Args: func(cmd *cobra.Command, args []string) error { + // Optionally run one of the validators provided by cobra + if err := cobra.MinimumNArgs(1)(cmd, args); err != nil { + return err + } + // Run the custom validation logic + if myapp.IsValidColor(args[0]) { + return nil + } + return fmt.Errorf("invalid color specified: %s", args[0]) + }, + Run: func(cmd *cobra.Command, args []string) { + fmt.Println("Hello, World!") + }, +} +``` + +## Example + +In the example below, we have defined three commands. Two are at the top level +and one (cmdTimes) is a child of one of the top commands. In this case the root +is not executable, meaning that a subcommand is required. This is accomplished +by not providing a 'Run' for the 'rootCmd'. + +We have only defined one flag for a single command. + +More documentation about flags is available at https://github.com/spf13/pflag + +```go +package main + +import ( + "fmt" + "strings" + + "github.com/spf13/cobra" +) + +func main() { + var echoTimes int + + var cmdPrint = &cobra.Command{ + Use: "print [string to print]", + Short: "Print anything to the screen", + Long: `print is for printing anything back to the screen. +For many years people have printed back to the screen.`, + Args: cobra.MinimumNArgs(1), + Run: func(cmd *cobra.Command, args []string) { + fmt.Println("Print: " + strings.Join(args, " ")) + }, + } + + var cmdEcho = &cobra.Command{ + Use: "echo [string to echo]", + Short: "Echo anything to the screen", + Long: `echo is for echoing anything back. +Echo works a lot like print, except it has a child command.`, + Args: cobra.MinimumNArgs(1), + Run: func(cmd *cobra.Command, args []string) { + fmt.Println("Echo: " + strings.Join(args, " ")) + }, + } + + var cmdTimes = &cobra.Command{ + Use: "times [string to echo]", + Short: "Echo anything to the screen more times", + Long: `echo things multiple times back to the user by providing +a count and a string.`, + Args: cobra.MinimumNArgs(1), + Run: func(cmd *cobra.Command, args []string) { + for i := 0; i < echoTimes; i++ { + fmt.Println("Echo: " + strings.Join(args, " ")) + } + }, + } + + cmdTimes.Flags().IntVarP(&echoTimes, "times", "t", 1, "times to echo the input") + + var rootCmd = &cobra.Command{Use: "app"} + rootCmd.AddCommand(cmdPrint, cmdEcho) + cmdEcho.AddCommand(cmdTimes) + rootCmd.Execute() +} +``` + +For a more complete example of a larger application, please checkout [Hugo](https://gohugo.io/). + +## Help Command + +Cobra automatically adds a help command to your application when you have subcommands. +This will be called when a user runs 'app help'. Additionally, help will also +support all other commands as input. Say, for instance, you have a command called +'create' without any additional configuration; Cobra will work when 'app help +create' is called. Every command will automatically have the '--help' flag added. + +### Example + +The following output is automatically generated by Cobra. Nothing beyond the +command and flag definitions are needed. + + $ cobra-cli help + + Cobra is a CLI library for Go that empowers applications. + This application is a tool to generate the needed files + to quickly create a Cobra application. + + Usage: + cobra-cli [command] + + Available Commands: + add Add a command to a Cobra Application + completion Generate the autocompletion script for the specified shell + help Help about any command + init Initialize a Cobra Application + + Flags: + -a, --author string author name for copyright attribution (default "YOUR NAME") + --config string config file (default is $HOME/.cobra.yaml) + -h, --help help for cobra-cli + -l, --license string name of license for the project + --viper use Viper for configuration + + Use "cobra-cli [command] --help" for more information about a command. + + +Help is just a command like any other. There is no special logic or behavior +around it. In fact, you can provide your own if you want. + +### Grouping commands in help + +Cobra supports grouping of available commands in the help output. To group commands, each group must be explicitly +defined using `AddGroup()` on the parent command. Then a subcommand can be added to a group using the `GroupID` element +of that subcommand. The groups will appear in the help output in the same order as they are defined using different +calls to `AddGroup()`. If you use the generated `help` or `completion` commands, you can set their group ids using +`SetHelpCommandGroupId()` and `SetCompletionCommandGroupId()` on the root command, respectively. + +### Defining your own help + +You can provide your own Help command or your own template for the default command to use +with the following functions: + +```go +cmd.SetHelpCommand(cmd *Command) +cmd.SetHelpFunc(f func(*Command, []string)) +cmd.SetHelpTemplate(s string) +``` + +The latter two will also apply to any children commands. + +## Usage Message + +When the user provides an invalid flag or invalid command, Cobra responds by +showing the user the 'usage'. + +### Example +You may recognize this from the help above. That's because the default help +embeds the usage as part of its output. + + $ cobra-cli --invalid + Error: unknown flag: --invalid + Usage: + cobra-cli [command] + + Available Commands: + add Add a command to a Cobra Application + completion Generate the autocompletion script for the specified shell + help Help about any command + init Initialize a Cobra Application + + Flags: + -a, --author string author name for copyright attribution (default "YOUR NAME") + --config string config file (default is $HOME/.cobra.yaml) + -h, --help help for cobra-cli + -l, --license string name of license for the project + --viper use Viper for configuration + + Use "cobra [command] --help" for more information about a command. + +### Defining your own usage +You can provide your own usage function or template for Cobra to use. +Like help, the function and template are overridable through public methods: + +```go +cmd.SetUsageFunc(f func(*Command) error) +cmd.SetUsageTemplate(s string) +``` + +## Version Flag + +Cobra adds a top-level '--version' flag if the Version field is set on the root command. +Running an application with the '--version' flag will print the version to stdout using +the version template. The template can be customized using the +`cmd.SetVersionTemplate(s string)` function. + +## PreRun and PostRun Hooks + +It is possible to run functions before or after the main `Run` function of your command. The `PersistentPreRun` and `PreRun` functions will be executed before `Run`. `PersistentPostRun` and `PostRun` will be executed after `Run`. The `Persistent*Run` functions will be inherited by children if they do not declare their own. These functions are run in the following order: + +- `PersistentPreRun` +- `PreRun` +- `Run` +- `PostRun` +- `PersistentPostRun` + +An example of two commands which use all of these features is below. When the subcommand is executed, it will run the root command's `PersistentPreRun` but not the root command's `PersistentPostRun`: + +```go +package main + +import ( + "fmt" + + "github.com/spf13/cobra" +) + +func main() { + + var rootCmd = &cobra.Command{ + Use: "root [sub]", + Short: "My root command", + PersistentPreRun: func(cmd *cobra.Command, args []string) { + fmt.Printf("Inside rootCmd PersistentPreRun with args: %v\n", args) + }, + PreRun: func(cmd *cobra.Command, args []string) { + fmt.Printf("Inside rootCmd PreRun with args: %v\n", args) + }, + Run: func(cmd *cobra.Command, args []string) { + fmt.Printf("Inside rootCmd Run with args: %v\n", args) + }, + PostRun: func(cmd *cobra.Command, args []string) { + fmt.Printf("Inside rootCmd PostRun with args: %v\n", args) + }, + PersistentPostRun: func(cmd *cobra.Command, args []string) { + fmt.Printf("Inside rootCmd PersistentPostRun with args: %v\n", args) + }, + } + + var subCmd = &cobra.Command{ + Use: "sub [no options!]", + Short: "My subcommand", + PreRun: func(cmd *cobra.Command, args []string) { + fmt.Printf("Inside subCmd PreRun with args: %v\n", args) + }, + Run: func(cmd *cobra.Command, args []string) { + fmt.Printf("Inside subCmd Run with args: %v\n", args) + }, + PostRun: func(cmd *cobra.Command, args []string) { + fmt.Printf("Inside subCmd PostRun with args: %v\n", args) + }, + PersistentPostRun: func(cmd *cobra.Command, args []string) { + fmt.Printf("Inside subCmd PersistentPostRun with args: %v\n", args) + }, + } + + rootCmd.AddCommand(subCmd) + + rootCmd.SetArgs([]string{""}) + rootCmd.Execute() + fmt.Println() + rootCmd.SetArgs([]string{"sub", "arg1", "arg2"}) + rootCmd.Execute() +} +``` + +Output: +``` +Inside rootCmd PersistentPreRun with args: [] +Inside rootCmd PreRun with args: [] +Inside rootCmd Run with args: [] +Inside rootCmd PostRun with args: [] +Inside rootCmd PersistentPostRun with args: [] + +Inside rootCmd PersistentPreRun with args: [arg1 arg2] +Inside subCmd PreRun with args: [arg1 arg2] +Inside subCmd Run with args: [arg1 arg2] +Inside subCmd PostRun with args: [arg1 arg2] +Inside subCmd PersistentPostRun with args: [arg1 arg2] +``` + +## Suggestions when "unknown command" happens + +Cobra will print automatic suggestions when "unknown command" errors happen. This allows Cobra to behave similarly to the `git` command when a typo happens. For example: + +``` +$ hugo srever +Error: unknown command "srever" for "hugo" + +Did you mean this? + server + +Run 'hugo --help' for usage. +``` + +Suggestions are automatically generated based on existing subcommands and use an implementation of [Levenshtein distance](https://en.wikipedia.org/wiki/Levenshtein_distance). Every registered command that matches a minimum distance of 2 (ignoring case) will be displayed as a suggestion. + +If you need to disable suggestions or tweak the string distance in your command, use: + +```go +command.DisableSuggestions = true +``` + +or + +```go +command.SuggestionsMinimumDistance = 1 +``` + +You can also explicitly set names for which a given command will be suggested using the `SuggestFor` attribute. This allows suggestions for strings that are not close in terms of string distance, but make sense in your set of commands but for which +you don't want aliases. Example: + +``` +$ kubectl remove +Error: unknown command "remove" for "kubectl" + +Did you mean this? + delete + +Run 'kubectl help' for usage. +``` + +## Generating documentation for your command + +Cobra can generate documentation based on subcommands, flags, etc. Read more about it in the [docs generation documentation](doc/README.md). + +## Generating shell completions + +Cobra can generate a shell-completion file for the following shells: bash, zsh, fish, PowerShell. If you add more information to your commands, these completions can be amazingly powerful and flexible. Read more about it in [Shell Completions](shell_completions.md). + +## Providing Active Help + +Cobra makes use of the shell-completion system to define a framework allowing you to provide Active Help to your users. Active Help are messages (hints, warnings, etc) printed as the program is being used. Read more about it in [Active Help](active_help.md). |