flagex

Extended flag parsing for Go. Reads command-line flags from configuration files, streams, and URLs on top of the standard flag package.

Usage

package main

import "flag"
import "github.com/pin2t/flagex"

var user = flag.String("user", "", "user name")
var port = flag.Int("port", 8080, "port number")

func main() {
    flag.Parse()
    flagex.ParseFile("app.conf")
    flagex.ParseURL("http://config-server/app.conf")
}

Format

Each line is name=value. Blank lines and lines starting with # are ignored. Flags already set on the command line take precedence.

File example

# app.conf
user=configuser
url=http://localhost:8332
listen=:9999
count=42
verbose=true
ratio=0.75

Environment variables example

With prefix APP_, environment variables map to flag names by stripping the prefix and converting to lowercase. For example, APP_URL sets the url flag.

export APP_USER=envuser
export APP_URL=http://env:9000
export APP_LISTEN=:8888
export APP_COUNT=99
export APP_VERBOSE=true
export APP_RATIO=1.5

Functions

• ParseFile(path) — reads configuration from a file.
• ParseStream(r) — reads configuration from an io.Reader.
• ParseURL(url) — fetches configuration via HTTP GET.
• ParseEnv(prefix) — fetches configuration from system environment variables.