dotenv

A lightweight, zero-dependency Go package for loading environment variables from .env and .env.local files into your application.

Features

• File Priority: Automatically loads .env and overrides with .env.local if present.
• Shell Support: Recognizes the export keyword.
• Comment Handling: Ignores lines starting with # and strips inline comments.
• Smart Quoting: Automatically handles values wrapped in single (') or double (") quotes.
• Zero Dependencies: Uses only the Go standard library.

Installation

go get github.com/rickferrdev/dotenv

Usage

1. Create your environment files

.env

PORT=8080
DB_URL="postgres://user:password@localhost:5432/db"
# This is a comment
DEBUG=true

.env.local

PORT=3000 # Overrides the value in .env

2. Load variables in Go

Call dotenv.Collect() as early as possible in your main function (or in an init function) to populate os.Environ.

package main

import (
    "fmt"
    "os"
    "github.com/rickferrdev/dotenv"
)

func main() {
    // Load variables from .env and .env.local
    dotenv.Collect()

    port := os.Getenv("PORT")
    fmt.Printf("Server starting on port: %s\n", port)
}

How it Works

• Collect(): Iterates through FilenameVariables (defaulting to .env and .env.local). It parses each line, strips the export prefix if it exists, and ignores comments.
• quotes(): A helper function that ensures values like KEY="value" or KEY='value' are stored simply as value, while also cleaning up trailing inline comments.

Configuration

You can override the files the package looks for by modifying the FilenameVariables slice before calling Collect:

dotenv.FilenameVariables = []string{".env.production", ".env"}
dotenv.Collect()