goenv

Description

goenv is a simple library that allows you to load environment variables into a model struct. And it supports nested structs too!

Features

• Supports nested structs
• Field names are converted to upper snake case by default
• Custom field names can be defined with env tag
• Default values can be defined with default tag
• Supports slice and map types
• Requirement check can be enabled with required tag like required:"true". It is disabled by default.
• Nested struct fields' variable names consist of parent struct name and field name. For example, DATABASE_HOST for Database struct { Host string }
• Field delimiter is underscore(_) by default. It can be disabled using env:"-". In this case struct field names will not contain parent struct name. For example, HOST for Database struct { Host string }

Installation

go get github.com/metinorak/goenv

Basic Usage

package main

import (
    "fmt"
    "github.com/metinorak/goenv"
)

// An example nested struct
type Config struct {
    Database struct {
        Host     string
        Port     int    
        Username string 
        Password string 
        Name     string
        MaxIdle  int
    }
    Server struct {
        Host string 
        Port int    
    }
    WebsiteUrl string
    FormulaConstants map[string]float64
    Proxies []string
}

func main() {
    // Example environment variables for the above struct
    // DATABASE_HOST=localhost
    // DATABASE_PORT=3306
    // DATABASE_USERNAME=root
    // DATABASE_PASSWORD=secret
    // DATABASE_NAME=example
    // DATABASE_MAX_IDLE=10
    // SERVER_HOST=localhost
    // SERVER_PORT=8080
    // WEBSITE_URL=http://localhost:8080
    // FORMULA_CONSTANTS=pi:3.14,e:2.71
    // PROXIES=example.com:8080,example2.com:8080

    // Following lines will load environment variables into Config struct
    // Field delimiter is underscore(_) by default

    var config Config

    err := goenv.Load(&config)
    if err != nil {
        panic(err)
    }

    fmt.Printf("%+v\n", config)
}

With Tags

package main

import (
    "fmt"
    "github.com/metinorak/goenv"
)

// An example nested struct
type Config struct {
    Database struct {
        Host     string     `env:"Host" default:"localhost"`
        Port     int        `env:"Port" default:"5000"`
        Username string     `env:"Username" required:"true"`
        Password string     `env:"Password" required:"true"`
        Name     string     `env:"Name" default:"example" required:"true"`
        MaxIdle  int        `env:"MaxIdle"`
    }  `env:"Database"`
    Server struct {
        Host string         `env:"Host"`
        Port int            `env:"Port"`
    } `env:"Server"`
    WebsiteUrl string       `env:"Website"`
    FormulaConstant float64 `env:"FormulaConstant" default:"3.14"`
}

func main() {
    // Example environment variables for the above struct
    // Database_Host=localhost
    // Database_Port=3306
    // Database_Username=root
    // Database_Password=secret
    // Database_Name=example
    // Database_MaxIdle=10
    // Server_Host=localhost
    // Server_Port=8080
    // Website=http://localhost:8080
    // FormulaConstant=3.14

    // Following lines will load environment variables into Config struct

    var config Config

    err := goenv.Load(&config)
    if err != nil {
        panic(err)
    }

    fmt.Printf("%+v\n", config)
}

With Disabled Parent Struct Name and Fields

package main

import (
    "fmt"
    "github.com/metinorak/goenv"
)

// An example nested struct
type Config struct {
    Database struct {
        Host     string     `env:"-" default:"localhost"`
        Port     int        `env:"-" default:"5000"`
        Username string     `env:"Username" required:"true"`
        Password string     `env:"Password" required:"true"`
        Name     string     `env:"Name" default:"example" required:"true"`
        MaxIdle  int        `env:"MaxIdle"`
    }  `env:"-"`
    Server struct {
        Host string         `env:"Host"`
        Port int            `env:"Port"`
    } `env:"Server"`
    WebsiteUrl string       `env:"Website"`
    FormulaConstant float64 `env:"-"`
}

func main() {
    // Example environment variables for the above struct
    // Username=root
    // Password=secret
    // Name=example
    // MaxIdle=10
    // Server_Host=localhost
    // Server_Port=8080
    // Website=http://localhost:8080

    // Following lines will load environment variables into Config struct

    var config Config

    
    err := goenv.Load(&config)
    if err != nil {
        panic(err)
    }
}

License

MIT