uniconfig

uniconfig

Simple golang configuration library which works with INI files, cmdline flags and environment variables.

This package is influenced by https://github.com/rakyll/globalconf, but is different: instead of defining flags for every option, you create a struct with all required fields, and uniconfig creates all flags for you.

Installation

go get github.com/a-kr/uniconfig

Usage

First, import the package:

import "github.com/a-kr/uniconfig"

Define the structure which will hold your configuration. uniconfig supports two-level structure nesting.

type MyConfig struct {
	Debug   bool
	Count   int `help:"number of items"`
	Nested1 struct {
		A       string
		B       string
		ignored string
	}
	Nested2 struct {
		Zzz bool
	}
}
...
config := MyConfig{}
// set some defaults here...
config.Count = 42

Pass the config structure to the library:

uniconfig.Load(&config)

This line will perform the following actions:

1. Check the command line for --config option and fill the config structure from INI file, if specified. The INI file can look like this:

    debug = true
    count = 65535
    ; this is a comment
    # also a comment
   
    [Nested1]
    A  = sometag
    b = something else
    irrelevant = ignored option
    number = 14
   

2. Overwrite config from environment variables. Environment variables are named in uppercase, like this: COUNT=65535 NESTED1_A=sometag.

3. Generate command line flags for each of config's public fields, parse the command line and overwrite config with parsed values. Command line options are named in lowercase, like this: --count 65535 --nested1-a sometag. The --help option will be handled here, printing something like this:

    -config="": path to configuration file
    -count=42: number of items
    -debug=false:
    -nested1-a="":
    -nested1-b="":
    -nested2-zzz=false:
   

   Note that the help text comes from the structure field tags (e.g. Count int `help:"number of items"` ).

You can dump the final config in the form of INI file:

fmt.Println(uniconfig.ConfigAsIniFile(config))

Example code

Clone this repository and try running example application in various ways:

git clone https://github.com/a-kr/uniconfig
cd uniconfig

NESTED1_A=bee go run example_app/example.go --count=45 --config=example_app/testconfig.ini
NESTED1_A=bee go run example_app/example.go --count=45
go run example_app/example.go --count=45