envconf

README

envconf

Go package for load and set environment variables from .env text files.

This code uses github.com/joho/godotenv package.

Installation

Needed third party package:

go get -u github.com/joho/godotenv

As a library in Go workspace:

go get -u gitlab.com/laniakeasoft/envconf

Overview

Load values defined in .env files and create environment variables at Operating System level.

Environment variables created along the Go code will only be acessible inside the Go project.

File: config.env

This file is always loaded, if it exists.

In this file there must exist a variable named as ENVIRONMENT.

The value of ENVIRONMENT can be: development, test, production.

If the value of ENVIRONMENT is different of the above ones or it is not defined, it will be: development.

The value of ENVIRONMENT is case insensitive.

File: config_xxx.env

Depending on the value of ENVIRONMENT, the corresponding file config_xxx.env will be loaded, if it exists.

xxx = development, test, production

Precedence of multiple values

If some variable is defined more than once, the value precedence is:

1. existing O.S. environment variable, defined at O.S. startup.

2. value defined in: config.env

3. value defined in: config_xxx.env

Usage example

On terminal, create an enviroment variable before the test:

$ EXTERNAL_VAR="Variable defined before the Go test"
$ export EXTERNAL_VAR
$ echo $EXTERNAL_VAR	# test if it was correctly created
Variable defined before the Go test

We are interested in observe that this external variable will not be affected by the envconf execution.

In go workspace, create the directories and files like the following structure:

src/
 |_yourtest/
    |_ main.go:
    |_ config.env
    |_ config_development.env
    |_ config_test.env
    |_ config_production.env

File main.go

package main

import (
	"fmt"
	"os"
	"gitlab.com/laniakeasoft/envconf"
)

func main() {
	fmt.Println("Environment variables before config:")
	printEnvironment()

	envconf.LoadEnvironmentVariables()

	fmt.Println("\nEnvironment variables after config:")
	printEnvironment()
}

func printEnvironment() {
	fmt.Println("ENVIRONMENT :", os.Getenv("ENVIRONMENT"))
	fmt.Println("SYSTEM_TITLE :", os.Getenv("SYSTEM_TITLE"))
	fmt.Println("SPECIFIC_VAR :", os.Getenv("SPECIFIC_VAR"))
	fmt.Println("EXTERNAL_VAR :", os.Getenv("EXTERNAL_VAR"))
}

File config.env

ENVIRONMENT=production
SYSTEM_TITLE="Environment variables with package envconfig"
EXTERNAL_VAR="Redefining the external variable"

File config_development.env

SPECIFIC_VAR="Specific variable at DEVELOPMENT config file"

File config_test.env

SPECIFIC_VAR="Specific variable at TEST config file"

File config_production.env

SPECIFIC_VAR="Specific variable at PRODUCTION config file"

Execution and results:

$ go run main.go 
Environment variables before config:
ENVIRONMENT : 
SYSTEM_TITLE : 
SPECIFIC_VAR : 
EXTERNAL_VAR : Variable defined before the Go test

Environment variables after config:
ENVIRONMENT : production
SYSTEM_TITLE : Environment variables with package envconfig
SPECIFIC_VAR : Specific variable at PRODUCTION config file
EXTERNAL_VAR : Variable defined before the Go test

Comments about the results

As we can see, the files config_development.env and config_test.env were not loaded because in file config.env the value of ENVIRONMENT is "production".

The existing environment variable (EXTERNAL_VAR) created before the test was not changed, as desired.

Thanks

Thank you for your interest and I hope envconf package can be useful for you!

If you have suggestions, they will be welcome.

Documentation

Index

• func LoadEnvironmentVariables()

Functions

func LoadEnvironmentVariables

func LoadEnvironmentVariables()

LoadEnvironmentVariables loads the .env configuration files and creates the corresponding environment variables at O.S. level.