envconfig

A low dependency package for .env files (or just environment variables).

Install

go get github.com/h-dav/envconfig

Usage

Set environment variables and populate a struct:

Code:

package main

import (
	"fmt"
	"log"
	"path/filepath"

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

// ExampleConfig is your config struct using `env` struct tags.
type ExampleConfig struct {
	Example      string  `env:"EXAMPLE,required"`
	AnotherValue string  `env:"ANOTHER_VALUE"`
	IntExample   int     `env:"INT_EXAMPLE"`
	Int32Example int32   `env:"INT32_EXAMPLE"`
	FloatExample float64 `env:"FLOAT_EXAMPLE"`
	Service      struct {
		Port int64  `env:"PORT"`
		Name string `env:"NAME,required"`
	} `env:"prefix=HTTP_"`
	ExampleEndpoint string `env:"EXAMPLE_ENDPOINT"`
	DefaultValue    string `env:"DEFAULT_VALUE,default=thevalue"`
}

func main() {
	cfg := ExampleConfig{}
	if err := envconfig.SetPopulate(filepath.Join("config", "example.env"), &cfg); err != nil {
		log.Fatal(err)
	}

	fmt.Printf("Populated Config: %+v\n", cfg)
}

.env file:

EXAMPLE: value
ANOTHER_VALUE: v0.0.0
INT_EXAMPLE: 4
INT32_EXAMPLE: 23
#COMMENTED_EXAMPLE: test
FLOAT_EXAMPLE: 4.44
HTTP_PORT: 9999
HTTP_NAME: example_name
DNS: example.com
EXAMPLE_ENDPOINT: https://${DNS}/v1

Output:

Populated Config: {Example:value AnotherValue:v0.0.0 IntExample:4 Int32Example:23 FloatExample:4.44 Service:{Port:9999 Name:example_name} ExampleEndpoint:https://example.com/v1 DefaultValue:thevalue}

Example - Set environment variables

Code:

...
if err := envconfig.SetVars(filepath.Join("examples", "example.env")); err != nil {
	panic(err)
}
...

Example - Populate a struct with environment variables

Code:

...
type ExampleConfig struct {
	Example      string  `env:"EXAMPLE,required"`
	AnotherValue string  `env:"ANOTHER_VALUE"`
	IntExample   int     `env:"INT_EXAMPLE"`
	Int32Example int32   `env:"INT32_EXAMPLE"`
	FloatExample float64 `env:"FLOAT_EXAMPLE"`
	Service      struct {
		Port int64  `env:"PORT"`
		Name string `env:"NAME,required"`
	} `env:"prefix=HTTP_"`
	ExampleEndpoint string `env:"EXAMPLE_ENDPOINT"`
	DefaultValue    string `env:"DEFAULT_VALUE,default=thevalue"`
}

cfg := ExampleConfig{}
if err := envconfig.Populate(&cfg); err != nil {
    panic(err)
}
...

Options

Tag Option	Type	Example
default	assignment	env:"KEY,default=dval"
prefix	assignment	env:"prefix=pstruct_"
required	flag	env:"KEYNAME,required"

Supported types

• Int, Int32, Int64
• String
• Float64