config

README

config

config uses a struct as input and populates the fields of this struct with parameters from command line, environment variables and configuration file.

Install

go get crg.eti.br/go/config

Example

package main

import "crg.eti.br/go/config"

/*
step 1: Declare your configuration struct,
it may or may not contain substructures.
*/

type mongoDB struct {
 Host string `cfgDefault:"example.com" cfgRequired:"true"`
 Port int    `cfgDefault:"999"`
}

type configTest struct {
 Domain    string
 DebugMode bool `json:"db" cfg:"db" cfgDefault:"false"`
 MongoDB   mongoDB
 IgnoreMe  string `cfg:"-"`
}

func main() {

 // step 2: Instantiate your structure.
 config := configTest{}

 // step 3: Pass the instance pointer to the parser
 err := config.Parse(&config)
 if err != nil {
  println(err)
  return
 }

 /*
    The parser populated your struct with the data
    it took from environment variables and command
    line and now you can use it.
 */

 println("config.Domain......:", config.Domain)
 println("config.DebugMode...:", config.DebugMode)
 println("config.MongoDB.Host:", config.MongoDB.Host)
 println("config.MongoDB.Port:", config.MongoDB.Port)
}

With the example above try environment variables like $DOMAIN or $MONGODB_HOST and run the example again to see what happens.

You can also try using parameters on the command line, try -h to see the help.

Contributing

• Fork the repo on GitHub
• Clone the project to your own machine
• Create a branch with your modifications git checkout -b fantastic-feature.
• Then commit your changes git commit -m 'Implementation of new fantastic feature'
• Make a push to your branch git push origin fantastic-feature.
• Submit a Pull Request so that we can review your changes

Documentation

Overview

Package config uses a struct as input and populates the fields of this struct with parameters fom command line, environment variables and configuration file.

Index

• Variables
• func DefaultUsage()
• func Parse(config interface{}) (err error)
• func PrintDefaults()
• type Fileformat

Examples

• Parse

Variables

var (

	// Tag to set main name of field.
	Tag = "cfg"

	// TagDefault to set default value.
	TagDefault = "cfgDefault"

	// TagHelper to set usage help line.
	TagHelper = "cfgHelper"

	// Path sets default config path.
	Path string

	// File name of default config file.
	File string

	// FileRequired config file required.
	FileRequired bool

	// HelpString temporarily saves help.
	HelpString string

	// PrefixFlag is a string that would be placed at the beginning of the generated Flag tags.
	PrefixFlag string

	// PrefixEnv is a string that would be placed at the beginning of the generated Event tags.
	PrefixEnv string

	// ErrFileFormatNotDefined Is the error that is returned when there is no defined configuration file format.
	ErrFileFormatNotDefined = errors.New("file format not defined")

	Usage func()

	// Formats is the list of registered formats.
	Formats []Fileformat

	// FileEnv is the enviroment variable that define the config file.
	FileEnv string

	// PathEnv is the enviroment variable that define the config file path.
	PathEnv string

	// WatchConfigFile is the flag to update the config when the config file changes.
	WatchConfigFile bool

	// DisableFlags on the command line.
	DisableFlags bool
)

Functions

func DefaultUsage

func DefaultUsage()

DefaultUsage is assigned for Usage function by default.

func Parse

func Parse(config interface{}) (err error)

Parse configuration.

Example

type config struct {
	Name  string `cfg:"Name" cfgDefault:"root"`
	Value int    `cfg:"Value" cfgDefault:"123"`
}

cfg := config{}

err := Parse(&cfg)
if err != nil {
	println(err)
}

println("Name:", cfg.Name, "Value:", cfg.Value)

func PrintDefaults

func PrintDefaults()

PrintDefaults print the default help.

Types

type Fileformat

type Fileformat struct {
	Extension   string
	Load        func(config interface{}) (err error)
	PrepareHelp func(config interface{}) (help string, err error)
}

Fileformat struct holds the functions to Load the file containing the settings.