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Table of Contents
Install godotenv
How to create and use .env files
Supports multiple environment configurations (such as .env.development and .env.production)
Some easily overlooked but important details
Home Backend Development Golang How to work with environment variables in golang using godotenv

How to work with environment variables in golang using godotenv

Jul 13, 2025 am 02:04 AM

The steps to manage Go project environment variables using godotenv are as follows: 1. Install the package and import it, and call godotenv.Load() to load the .env file; 2. Create a .env file in the .key=value format in the project root directory for code to read through os.Getenv; 3. Support multi-environment configuration by specifying file names such as .env.development; 4. Be careful to avoid submitting .env to Git, support nested variable references and default value processing. In addition, it is recommended to directly inject system variables in the production environment.

How to work with environment variables in golang using godotenv

Using .env files to manage environment variables is a common requirement in Go projects, and godotenv is a very popular library that allows you to read environment variables like production environments when developing locally. Below are some practical uses and precautions.

How to work with environment variables in golang using godotenv

Install godotenv

To use godotenv , you first need to install its Go package:

How to work with environment variables in golang using godotenv
 go get github.com/joho/godotenv/autoload

Or if you just want to load manually at initialization, you can just introduce:

 go get github.com/joho/godotenv

Then import and call in the code:

How to work with environment variables in golang using godotenv
 import "github.com/joho/godotenv"

err := godotenv.Load()
if err != nil {
    // Handle errors, such as file does not exist, etc.}

How to create and use .env files

The .env file is usually placed in the project root directory, and the content format is as follows:

 DB_USER=myuser
DB_PASSWORD=secret123
PORT=8080

These values can be obtained in the code by os.Getenv("DB_USER") .

Note: If a variable is not defined in .env , os.Getenv will return an empty string. Therefore, it is best to make a non-empty judgment before use.


Supports multiple environment configurations (such as .env.development and .env.production)

Sometimes you want to load different .env files according to the current running environment. For example:

  • .env.development
  • .env.production

You can specify which file to load like this:

 godotenv.Load(".env." os.Getenv("GO_ENV"))

If you do not set GO_ENV , you can set it to development by default:

 env := os.Getenv("GO_ENV")
if env == "" {
    env = "development"
}
godotenv.Load(".env." env)

This way, you can flexibly switch configurations in different environments.


Some easily overlooked but important details

  • Don't submit .env to Git
    Remember to add .env to .gitignore to avoid leakage of sensitive information.

  • Support nested variable references
    For example, you can write it as:

     HOST=localhost
    URL=http://${HOST}:8080

    In this way os.Getenv("URL") will be http://localhost:8080 .

  • Default value processing
    If the variable may be missing, you can use os.Getenv to add judgment, or use os.LookupEnv to handle it more safely:

     port, exists := os.LookupEnv("PORT")
    if !exists {
        port = "8000"
    }

    Basically that's it. Using godotenv well can make local development more convenient and configuration more unified. Remember not to abuse it. It is recommended to inject configuration directly through system environment variables in the production environment.

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