Overview

properties is a Go library for reading and writing properties files.

It supports reading from multiple files or URLs and Spring style recursive property expansion of expressions like ${key} to their corresponding value. Value expressions can refer to other keys like in ${key} or to environment variables like in ${USER}. Filenames can also contain environment variables like in /home/${USER}/myapp.properties.

Properties can be decoded into structs, maps, arrays and values through struct tags.

Comments and the order of keys are preserved. Comments can be modified and can be written to the output.

The properties library supports both ISO-8859-1 and UTF-8 encoded data.

Starting from version 1.3.0 the behavior of the MustXXX() functions is configurable by providing a custom ErrorHandler function. The default has changed from panic to log.Fatal but this is configurable and custom error handling functions can be provided. See the package documentation for details.

Read the full documentation on

Getting Started

import (
	"flag"
	"github.com/magiconair/properties"
)

func main() {
	// init from a file
	p := properties.MustLoadFile("${HOME}/config.properties", properties.UTF8)

	// or multiple files
	p = properties.MustLoadFiles([]string{
			"${HOME}/config.properties",
			"${HOME}/config-${USER}.properties",
		}, properties.UTF8, true)

	// or from a map
	p = properties.LoadMap(map[string]string{"key": "value", "abc": "def"})

	// or from a string
	p = properties.MustLoadString("key=value\nabc=def")

	// or from a URL
	p = properties.MustLoadURL("http://host/path")

	// or from multiple URLs
	p = properties.MustLoadURL([]string{
			"http://host/config",
			"http://host/config-${USER}",
		}, true)

	// or from flags
	p.MustFlag(flag.CommandLine)

	// get values through getters
	host := p.MustGetString("host")
	port := p.GetInt("port", 8080)

	// or through Decode
	type Config struct {
		Host    string        `properties:"host"`
		Port    int           `properties:"port,default=9000"`
		Accept  []string      `properties:"accept,default=image/png;image;gif"`
		Timeout time.Duration `properties:"timeout,default=5s"`
	}
	var cfg Config
	if err := p.Decode(&cfg); err != nil {
		log.Fatal(err)
	}
}

Installation and Upgrade

$ go get -u github.com/magiconair/properties

License

2 clause BSD license. See LICENSE file for details.

ToDo

• Dump contents with passwords and secrets obscured