go-ini

Before You Start

• Applies to: Go 1.21+ (examples verified with Go 1.22) · Prerequisites: Std: strings · Read time: about 10 min

Repository: go-ini/ini: Package ini provides INI file read and write functionality in Go (github.com)

Documentation: go-ini/ini: Awesome Go INI file parsing (unknwon.cn)

Introduction

An ini file parsing library written in Go, supporting serialization and deserialization, struct mapping, and comment operations.

Installation

go get gopkg.in/ini.v1

Quick Start

ini file as follows

# possible values : production, development
app_mode = development

[paths]
# Path to where grafana can store temp files, sessions, and the sqlite3 db (if that is used)
data = /home/git/grafana

[server]
# Protocol (http or https)
protocol = http

# The http port  to use
http_port = 9999

# Redirect to correct domain if host header does not match domain
# Prevents DNS rebinding attacks
enforce_domain = true

go file

package main

import (
    "fmt"
    "os"

    "gopkg.in/ini.v1"
)

func main() {
    cfg, err := ini.Load("my.ini")
    if err != nil {
        fmt.Printf("Fail to read file: %v", err)
        os.Exit(1)
    }

    // Typical read operation, default section can be represented by empty string
    fmt.Println("App Mode:", cfg.Section("").Key("app_mode").String())
    fmt.Println("Data Path:", cfg.Section("paths").Key("data").String())

    // We can do some operations with candidate value restrictions
    fmt.Println("Server Protocol:",
        cfg.Section("server").Key("protocol").In("http", []string{"http", "https"}))
    // If the read value is not in the candidate list, it will fall back to the provided default value
    fmt.Println("Email Protocol:",
        cfg.Section("server").Key("protocol").In("smtp", []string{"imap", "smtp"}))

    // Try automatic type conversion
    fmt.Printf("Port Number: (%[1]T) %[1]d\n", cfg.Section("server").Key("http_port").MustInt(9999))
    fmt.Printf("Enforce Domain: (%[1]T) %[1]v\n", cfg.Section("server").Key("enforce_domain").MustBool(false))

    // That's about it, modify a value and save
    cfg.Section("").Key("app_mode").SetValue("production")
    cfg.SaveTo("my.ini.local")
}

Output

$ go run main.go
App Mode: development
Data Path: /home/git/grafana
Server Protocol: http
Email Protocol: smtp
Port Number: (int) 9999
Enforce Domain: (bool) true

$ cat my.ini.local
# possible values : production, development
app_mode = production

[paths]
# Path to where grafana can store temp files, sessions, and the sqlite3 db (if that is used)
data = /home/git/grafana
...

Complete Example

The program below runs as-is: copy it into a file and execute go run main.go, or paste it into the Go Playground.

package main

import (
	"fmt"
	"strings"
)

func main() {
	content := "[server]\nport = 8080\nhost = localhost\n"
	values := map[string]string{}

	for _, line := range strings.Split(content, "\n") {
		line = strings.TrimSpace(line)
		if line == "" || strings.HasPrefix(line, "[") {
			continue
		}
		if k, v, ok := strings.Cut(line, "="); ok {
			values[strings.TrimSpace(k)] = strings.TrimSpace(v)
		}
	}

	fmt.Println(values["host"], values["port"])
}

Expected output:

localhost 8080

Common Pitfalls

• INI is not a standard. Each dialect differs on quoting, escapes and multi-line values; use the library for real files.
• Section names matter. A key may exist in several sections; flatten honestly or keep the section in the lookup.
• Watch whitespace. key = value and key=value are both common; trim consistently.
• Encoding is up to you. The library returns strings; parse numbers and booleans explicitly.
• Do not treat INI as a schema. For nested configuration prefer YAML/TOML/JSON.

Change Log

• 2026-10-14: Added "Before You Start" notes, a complete runnable example with expected output, common pitfalls, and this change log. Closed a code block that was left unterminated.