goflenfig

goflenfig : A super simple flag and config package

Overview

goflenfig is a semi-drop-in replacement (only StringVar, IntVar and BoolVar are currently implemented) for the standard flag package. It is extremely simple to use and allows flags to be specified either as arguments on the command-line, environment variables or configuration in a JSON file.

It is not intended as a replacement for "commander"-style libraries or as a fully-fledged configuration file library.

It is intended to make a 12-factor style application a little easier to build and test. I use this quite a lot for microservices deployed in Kubernetes.

Install

go get git.sr.ht/~yoink00/goflenfig

Usage

The order of precedence is:

1. Command-line argument (preferred)
2. Environment variable
3. Configuration file (least preferred)

The configuration file is searched (for *NIX platforms) according to the XDG standard in these directories:

1. $XDG_CONFIG_HOME/<sub-directory> or $HOME/.config/<sub-directory>
2. Iterating through the list of directories in $XDG_CONFIG_DIRS looking for a sub-directory called <sub-directory> stopping at the first one found.
3. /etc/<sub-directory>

The name of <sub-directory> is either the name of the binary (path.Base(os.Args[0])) but this can be overriden using ConfigDirectory().

The name of the config file defaults to config but this can be overriden with ConfigFilename().

The package performs some case-conversion:

• JSON map names use lowerCamelCase
• Environment variable names use SCREAMING_SNAKE_CASE
• Command-line flags are not converted but kebab-case is commonly used

Example

package main

import (
	"git.sr.ht/~yoink00/goflenfig"
)

var testFlag     string
var testIntFlag  int
var testBoolFlag bool

func init() {
	goflenfig.Prefix("TEST_")
	goflenfig.StringVar(&testFlag, "test", "default", "Specify a test flag")
	goflenfig.IntVar(&testIntFlag, "test_int", 100, "Specify a test int flag")
	goflenfig.BoolVar(&testBoolFlag, "test_bool", false, "Specify a test bool flag")
}

func main() {
	goflenfig.Parse()

	fmt.Println(testFlag)
	fmt.Println(testIntFlag)
	fmt.Println(testBoolFlag)
}

Contributing

Code contributions

The goflenfig project uses the git send-email for collaborating. The tools are usually baked into Git and are used by projects like the Linux kernel, PostgreSQL and Git. This link will guide you through setting it up if you need to.

Please submit any patches in a plaintext email to ~yoink00/goflenfig@lists.sr.ht or if for some reason that doesn't work to u.yoink00.goflenfig@lists.sr.ht.

Anything else

Feel free to send any comments, issues or questions in a plaintext email to ~yoink00/goflenfig@lists.sr.ht or if for some reason that doesn't work to u.yoink00.goflenfig@lists.sr.ht.

Author

Stuart Wallace

License

MIT