config-file-parser-go

config-file-parser-go is a simple and lightweight Key-Value configuration file parser for Go. It easily parses simple, space-separated formats commonly found in Linux config files, making them easy to use within your Go applications. For more infomation, refer the document page below: https://pkg.go.dev/github.com/ebishrimp/config-file-parser-go

Installation

go get github.com/ebishrimp/config-file-parser-go

Latest version (strongry recommended)

Features

• Simple: Zero external dependencies (uses only the Go standard library).
• Lightweight: Accepts an io.Reader, ensuring a low memory footprint even when processing large files.
• Versatile: The same key can hold both single or multiple value(s).
• Intuitive Rules:
  • Use ParseConfig() method for parse config files.
  • Space-separated forms is allowed but, "strings with spaces" , quoted form is allowed to include spaces.
  • Only #-prefix lines will be ignored but non-prefix strings including # can be parsed as keys or values.
  • If there are grammatical error, then lines and error will return as ParseError struct.
  • Declaration of multiple values is required to written each lines.
  • When there are two or more spaces in quotes, they will be converted to single space.

Sample

Example of configuration

# Server settings
port 8080
debug_mode yes

# Multiple values for the same key
api_endpoint "https://primary.api.com"
api_endpoint "https://backup.api.com"

# Numeric and float values
timeout 30
ratio 0.75

sample code

package main

import (
	"fmt"
	"log"
	"os"

	"github.com/ebishrimp/config-file-parser-go"
)

func main() {
	// 1. Open the configuration file
	file, err := os.Open("config.conf")
	if err != nil {
		log.Fatalf("failed to open file: %v", err)
	}
	defer file.Close()

	// 2. Parse the configuration
	// ParseConfig returns *ConfigurationMap and ParseError (error interface)
	conf, err := confparser.ParseConfig(file)
	if err != nil {
		// ParseError contains the line number and a detailed message
		log.Fatalf("Parse error at %v", err)
	}

	// 3. Get single values (String, Int, Float, Bool)
	// Bool() supports "yes/no", "y/n", and "true/false" (case-insensitive)
	port, _ := conf.Int("port")
	debug, _ := conf.Bool("debug_mode")

	fmt.Printf("Server running on port: %d (Debug: %v)\n", port, debug)

	// 4. Get multiple values (StringSlice, IntSlice, etc.)
	endpoints := conf.StringSlice("api_endpoint")
	fmt.Printf("Found %d endpoints:\n", len(endpoints))
	for i, url := range endpoints {
		fmt.Printf("  [%d] %s\n", i, url)
	}

	// 5. Check existence and count of values
	if conf.Exists("timeout") {
		t, _ := conf.Int("timeout")
		fmt.Printf("Timeout: %v seconds\n", t)
	}

	if count, err := conf.Length("api_endpoint"); err == nil {
		fmt.Printf("Total api_endpoint entries: %d\n", count)
	}
}

This code is generated by gemini.

Legacy version

Features

• Simple: Zero external dependencies (uses only the Go standard library).
• Lightweight: Accepts an io.Reader, ensuring a low memory footprint even when processing large files.
• Intuitive Rules:
  • Use Parse() method.
  • Parses space- or tab-separated entries (e.g., key value).
  • Ignores anything after a # as a comment.
  • Safely skips empty lines and lines with three or more elements (e.g., key value1 value2) as invalid formats.
• Multiple Values:
  • Use ParseMultipleValues() method
  • All values are stored into slices

Sample

Usage

1. Prepare a Configuration File Create a config file (e.g., config.conf) that you want to parse.

# Example of config.conf
port 8080
host localhost

# Lines with 3 or more elements will be ignored
invalid_key too many values

# Example of config.conf which can be parsed by ParseMultipleValues(r io.Reader)
# The same key can hold multiple values
multiplevalues value1
multiplevalues value2

# Simultaneous description of values will be ignored
invalid_form value3 value4 value5

2. Use in Your Go Code You can parse directly from a file or a string, as long as it satisfies the io.Reader interface.

package main

import (
	"fmt"
	"log"
	"os"

	confparser "github.com/ebishrimp/config-file-parser-go"
)

func main() {
	// 1. Open the file (you can also pass a string using strings.NewReader)
	f, err := os.Open("config.conf")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	// 2. Parse the configuration
	conf, err := confparser.Parse(f)
	if err != nil {
		log.Fatalf("Parse error: %v", err)
	}

	// 3. Retrieve values

	// Get as a string
	host := conf.GetValue("host")
	fmt.Printf("Host: %s\n", host)

	// Get as an integer
	port, err := conf.IntGetValue("port")
	if err != nil {
		log.Printf("Failed to get port: %v", err)
	} else {
		fmt.Printf("Port: %d\n", port)
	}

	// Check if a key exists
	if conf.ExistsValue("invalid_key") {
		fmt.Println("invalid_key exists")
	} else {
		fmt.Println("invalid_key does not exist because it was skipped")
	}

	// 4. Parse multiple values
	multiConf, err := confparser.ParseMultipleValues(f)
	if err != nil {
		log.Fatalf("Parse error: %v", err)
	}

	// 5. Retrieve values

	// Get string slice
	multival := multiConf.GetMultipleValues("multiplevalues")
	// multival[0] == "value1"
	// multival[1] == "value2"

	// Get a first contest of slice
	firstval := multiConf.GetFirstValue("multiplevalues")
	// firstval == "value1"

	// Check if a key exists
	if conf.ExistsMultipleValues("invalid_form") {
		fmt.Println("invalid_form exists")
	} else {
		fmt.Println("invalid_form does not exist because it was skipped")
	}
}