OS Environment

This package aims to provide extension of the os.Getenv that supports different types of variable types, and allows to specify a default value, in case the environment variable is missing.

This version is implemented with Go 1.18+ generics. If you need to use the package's functionailty in Go versions prior to 1.18, see below.

There are two versions of the package:

• v2: uses generics, therefore can only be compiled with Go 1.18+ (this version).
• v1: supports Go versions 1.12+.

Go 1.18+ (v2):

import "github.com/rusq/osenv/v2"

Go 1.12+ (v1):

import "github.com/rusq/osenv"

Usage

package main

import (
	"fmt"
	"math"
	"time"

	"github.com/rusq/osenv/v2"
)

func main() {
	fmt.Printf("OSENV_BOOL: %v\n"+
		"OSENV_DURATION: %s\n"+
		"OSENV_FLOAT: %.7f\n"+
		"OSENV_INT: %d\n"+
		"OSENV_INT64: %d\n"+
		"OSENV_STRING: %s\n"+
		"OSENV_TIME: %s\n",

		osenv.Value("OSENV_BOOL", true),
		osenv.Value("OSENV_DURATION", 60*time.Second),
		osenv.Value("OSENV_FLOAT", math.Pi),
		osenv.Value("OSENV_INT", math.MaxInt32),
		osenv.Value("OSENV_INT64", math.MaxInt64),
		osenv.Value("OSENV_STRING", "default string value"),
		osenv.Value("OSENV_TIME", time.Date(2020, 12, 31, 23, 59, 59, 0, time.UTC)),
	)
}

For more examples, refer to package documentation

The package defines a single function that handles all supported types:

• Boolean
• time.Duration
• Float64
• Int
• Int64
• String
• Secret*
• Time

For all of these types, call osenv.Value(...).

* Secret obtains a string from the environment (osenv.Secret). The only difference between Value and Secret, is that Secret unsets the environment variable after getting the value.

Upgrading from v1 to v2

If you were using osenv/v1 before, and upgrading to osenv/v2, follow the instructions in this section.

Replace the call to the function in "From" with the call to the function in "To":

From	To
osenv.Bool	osenv.Value
osenv.Duration	osenv.Value
osenv.Float	osenv.Value
osenv.Int	osenv.Value
osenv.Int64	osenv.Value
osenv.Time	osenv.Value
osenv.String	osenv.Value