lookupcfg

Easily define and populate your configs from any kind of source using lookup function!

What is lookup function?

Lookup function is a function which accepts only one argument: key (of type string) and returns two values:

• value (of type string string) - value which matches with the provided key
• found (of type bool) - is equal to true if provided key exists and value was found. Otherwise, it is equal to false

Signature of lookup functions (in Go):

func(key string) (value string, found bool)

Installation

go get github.com/jieggii/lookupcfg

Usage

It's so simple!

First of all, define your config struct and create config instance:

package main

import "github.com/jieggii/lookupcfg"

func main() {
    type Config struct {
        Host string `env:"HOST"` // use tags to define source name (key)
                                 // and value name in this source (value)
	Port int `env:"PORT"`
    }
    config := Config{}
}

Then choose lookup function which will be used to fill fields of the config struct. In this example we will define own lookup function, which simply uses os.LookupEnv function.

package main

import (
	"github.com/jieggii/lookupcfg"
	"os"
)

func lookup(key string) (value string, found bool) {
	return os.LookupEnv(key)
}

func main() {
	type Config struct {
		Host string `env:"HOST"` // use tags to define source name (key)
                                         // and value name in this source (value)
		Port int `env:"PORT"`
	}
	config := Config{}
}

Let's finally fill our config with some values from environment variables and print the result!

package main

import (
	"fmt"
	"github.com/jieggii/lookupcfg"
	"os"
)

func lookup(key string) (value string, found bool) {
	return os.LookupEnv(key)
}

func main() {
	type Config struct {
		Host string `env:"HOST"` // use tags to define source name (key)
                                         // and value name in this source (value)
		Port int `env:"PORT"`
	}
	config := Config{}
	result := lookupcfg.PopulateConfig(
		"env",   // name of the source defined in struct's field tags
		lookup,  // our lookup function
		&config, // pointer to our config instance
	) // populating our config instance with values from environmental variables

	fmt.Printf("Population result: %+v\n", result)
	// >>> Population result: &{MissingFields:[] IncorrectTypeFields:[]}

	// print our populated config instance
	fmt.Printf("My config: %+v\n", config)
	// >>> My config: {Host:localhost Port:8888}
}

Done!

More examples can be found in the examples directory (´｡• ◡ •｡`) ♡.