a-kr / uniconfig

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

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