envconfig

Package envconfig provides functionality to easily populate your config structure by using both environment variables, and a .env file (optional).

• Installation
• Features
  • Options
  • Supported Data Types
• Usage

Installation

go get github.com/h-dav/envconfig/v2

Features

Options

• required: true or false
• default: Default value if environment variable is not set.
• prefix: Used for nested structures.
• envjson: Used for deserialising json into config.
• Text Replacement: ${EXAMPLE} can be used to insert other environment variables.

Supported Data Types

• string (slice compatible)
• int (slice compatible)
• float (slice compatible)
• bool
• time.Duration

Usage

package main

import (
    "time"

    "github.com/h-dav/envconfig/v2"
)

type Config struct {
    // Fields must be exported to be populated.
    LogLevel string `env:"LOG_LEVEL" default:"info"`
    Server struct {
        Port string `env:"PORT" required:"true"`
    } `prefix:"SERVER_"`
    JSONField struct {
        First string `json:"first"`
    } `envjson:"JSON_FIELD"`
    SliceIntField []int `env:"SLICE_INT_FIELD"`
    DurationField time.Duration `env:"DURATION"`
}

func main() {
    var cfg Config

    if err := envconfig.Set("./config/default.env", &cfg); err != nil {
        ...
    }
}

Corresponding .env file:

LOG_LEVEL=debug
SERVER_PORT=8080
JSON_FIELD={"first": "example"}
SLICE_INT_FIELD=1, 2, 3
DURATION=30s

Note

See test cases for more usage examples.

Note

This package takes heavy inspiration from httputil for handling reflection.