getenv

package module
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 Go to latest Published: Feb 20, 2024 License: MIT Imports: 4 Imported by: 2

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getenv

Package getenv provides a simple way to get environment variables. It's type-safe and supports built-in types and slices of them.

Types supported:

  • string
  • []string
  • int
  • []int
  • int8
  • []int8
  • int16
  • []int16
  • int32
  • []int32
  • int64
  • []int64
  • uint8
  • []uint8
  • uint16
  • []uint16
  • uint64
  • []uint64
  • uint
  • []uint
  • uintptr
  • []uintptr
  • uint32
  • []uint32
  • float32
  • []float32
  • float64
  • []float64
  • time.Time
  • []time.Time
  • time.Duration
  • []time.Duration
  • bool
  • []bool
  • url.URL
  • []url.URL
  • net.IP
  • []net.IP
  • complex64
  • []complex64
  • complex128
  • []complex128

Examples

Env

Env retrieves the value of the environment variable named by the key. If the variable is present in the environment the value will be parsed and returned. Otherwise, an error will be returned.

package main

import (
	"fmt"
	"net"
	"net/url"
	"os"
	"time"

	"github.com/obalunenko/getenv"
	"github.com/obalunenko/getenv/option"
)

func main() {
	const (
		key = "GH_GETENV_TEST"
	)

	var (
		val any
		err error
	)

	defer func() {
		if err = os.Unsetenv(key); err != nil {
			panic(err)
		}
	}()

	// string
	if err = os.Setenv(key, "golly"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[string](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// int
	if err = os.Setenv(key, "123"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[int](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// int conversion error
	if err = os.Setenv(key, "123s4"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[int](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// time.Time
	if err = os.Setenv(key, "2022-01-20"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[time.Time](key, option.WithTimeLayout("2006-01-02"))
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// []float64
	if err = os.Setenv(key, "26.89,0.67"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[[]float64](key, option.WithSeparator(","))
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// time.Duration
	if err = os.Setenv(key, "2h35m"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[time.Duration](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// url.URL
	if err = os.Setenv(key, "https://test:abcd123@golangbyexample.com:8000/tutorials/intro?type=advance&compact=false#history"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[url.URL](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// net.IP
	if err = os.Setenv(key, "2001:cb8::17"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[net.IP](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// []string
	if err = os.Setenv(key, "a,b,c,d"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[[]string](key, option.WithSeparator(","))
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// complex128
	if err = os.Setenv(key, "1+2i"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[complex128](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// []complex64
	if err = os.Setenv(key, "1+2i,3+4i"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[[]complex64](key, option.WithSeparator(","))
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

}

Output:

[string]: golly; err: <nil>
[int]: 123; err: <nil>
[int]: 0; err: could not parse variable[GH_GETENV_TEST] value[123s4] to type[int]: invalid value
[time.Time]: 2022-01-20 00:00:00 +0000 UTC; err: <nil>
[[]float64]: [26.89 0.67]; err: <nil>
[time.Duration]: 2h35m0s; err: <nil>
[url.URL]: {https  test:abcd123 golangbyexample.com:8000 /tutorials/intro  false false type=advance&compact=false history }; err: <nil>
[net.IP]: 2001:cb8::17; err: <nil>
[[]string]: [a b c d]; err: <nil>
[complex128]: (1+2i); err: <nil>
[[]complex64]: [(1+2i) (3+4i)]; err: <nil>
EnvOrDefault

EnvOrDefault retrieves the value of the environment variable named by the key. If the variable is present in the environment the value will be parsed and returned. Otherwise, the default value will be returned. The value returned will be of the same type as the default value.

package main

import (
	"fmt"
	"net"
	"net/url"
	"os"
	"time"

	"github.com/obalunenko/getenv"
	"github.com/obalunenko/getenv/option"
)

func main() {
	const (
		key = "GH_GETENV_TEST"
	)

	defer func() {
		if err := os.Unsetenv(key); err != nil {
			panic(err)
		}
	}()

	var val any

	// string
	if err := os.Setenv(key, "golly"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, "golly")
	fmt.Printf("[%T]: %v\n", val, val)

	// int
	if err := os.Setenv(key, "123"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, -99)
	fmt.Printf("[%T]: %v\n", val, val)

	// time.Time
	if err := os.Setenv(key, "2022-01-20"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key,
		time.Date(1992, 12, 1, 0, 0, 0, 0, time.UTC),
		option.WithTimeLayout("2006-01-02"),
	)
	fmt.Printf("[%T]: %v\n", val, val)

	// []float64
	if err := os.Setenv(key, "26.89,0.67"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, []float64{-99},
		option.WithSeparator(","),
	)
	fmt.Printf("[%T]: %v\n", val, val)

	// time.Duration
	if err := os.Setenv(key, "2h35m"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, time.Second)
	fmt.Printf("[%T]: %v\n", val, val)

	// url.URL
	if err := os.Setenv(key, "https://test:abcd123@golangbyexample.com:8000/tutorials/intro?type=advance&compact=false#history"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, url.URL{})
	fmt.Printf("[%T]: %v\n", val, val)

	// net.IP
	if err := os.Setenv(key, "2001:cb8::17"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, net.IP{})
	fmt.Printf("[%T]: %v\n", val, val)

	// []string
	if err := os.Setenv(key, "a,b,c,d"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, []string{}, option.WithSeparator(","))
	fmt.Printf("[%T]: %v\n", val, val)

	// complex128
	if err := os.Setenv(key, "1+2i"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, complex128(0))
	fmt.Printf("[%T]: %v\n", val, val)

	// []complex64
	if err := os.Setenv(key, "1+2i,3+4i"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, []complex64{}, option.WithSeparator(","))
	fmt.Printf("[%T]: %v\n", val, val)

}

Output:

[string]: golly
[int]: 123
[time.Time]: 2022-01-20 00:00:00 +0000 UTC
[[]float64]: [26.89 0.67]
[time.Duration]: 2h35m0s
[url.URL]: {https  test:abcd123 golangbyexample.com:8000 /tutorials/intro  false false type=advance&compact=false history }
[net.IP]: 2001:cb8::17
[[]string]: [a b c d]
[complex128]: (1+2i)
[[]complex64]: [(1+2i) (3+4i)]

Documentation

Overview

Package getenv provides a simple way to get environment variables. It's type-safe and supports built-in types and slices of them.

Types supported: - string - []string - int - []int - int8 - []int8 - int16 - []int16 - int32 - []int32 - int64 - []int64 - uint8 - []uint8 - uint16 - []uint16 - uint64 - []uint64 - uint - []uint - uintptr - []uintptr - uint32 - []uint32 - float32 - []float32 - float64 - []float64 - time.Time - []time.Time - time.Duration - []time.Duration - bool - []bool - url.URL - []url.URL - net.IP - []net.IP - complex64 - []complex64 - complex128 - []complex128

Index

Examples

Constants

This section is empty.

Variables

View Source 
var (
	// ErrNotSet is an error that is returned when the environment variable is not set.
	ErrNotSet = errors.New("not set")
	// ErrInvalidValue is an error that is returned when the environment variable is not valid.
	ErrInvalidValue = errors.New("invalid value")
)

Functions

func Env added in v1.10.0 

func Env[T internal.EnvParsable](key string, options ...option.Option) (T, error)

Env retrieves the value of the environment variable named by the key. If the variable is present in the environment, the value will be parsed and returned. Otherwise, an error will be returned.

Example 
package main

import (
	"fmt"
	"net"
	"net/url"
	"os"
	"time"

	"github.com/obalunenko/getenv"
	"github.com/obalunenko/getenv/option"
)

func main() {
	const (
		key = "GH_GETENV_TEST"
	)

	var (
		val any
		err error
	)

	defer func() {
		if err = os.Unsetenv(key); err != nil {
			panic(err)
		}
	}()

	// string
	if err = os.Setenv(key, "golly"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[string](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// int
	if err = os.Setenv(key, "123"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[int](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// int conversion error
	if err = os.Setenv(key, "123s4"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[int](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// time.Time
	if err = os.Setenv(key, "2022-01-20"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[time.Time](key, option.WithTimeLayout("2006-01-02"))
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// []float64
	if err = os.Setenv(key, "26.89,0.67"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[[]float64](key, option.WithSeparator(","))
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// time.Duration
	if err = os.Setenv(key, "2h35m"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[time.Duration](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// url.URL
	if err = os.Setenv(key, "https://test:abcd123@golangbyexample.com:8000/tutorials/intro?type=advance&compact=false#history"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[url.URL](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// net.IP
	if err = os.Setenv(key, "2001:cb8::17"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[net.IP](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// []string
	if err = os.Setenv(key, "a,b,c,d"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[[]string](key, option.WithSeparator(","))
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// complex128
	if err = os.Setenv(key, "1+2i"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[complex128](key)
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

	// []complex64
	if err = os.Setenv(key, "1+2i,3+4i"); err != nil {
		panic(err)
	}

	val, err = getenv.Env[[]complex64](key, option.WithSeparator(","))
	fmt.Printf("[%T]: %v; err: %v\n", val, val, err)

}

Output:

[string]: golly; err: <nil>
[int]: 123; err: <nil>
[int]: 0; err: failed to parse environment variable[GH_GETENV_TEST]: invalid value
[time.Time]: 2022-01-20 00:00:00 +0000 UTC; err: <nil>
[[]float64]: [26.89 0.67]; err: <nil>
[time.Duration]: 2h35m0s; err: <nil>
[url.URL]: {https  test:abcd123 golangbyexample.com:8000 /tutorials/intro  false false type=advance&compact=false history }; err: <nil>
[net.IP]: 2001:cb8::17; err: <nil>
[[]string]: [a b c d]; err: <nil>
[complex128]: (1+2i); err: <nil>
[[]complex64]: [(1+2i) (3+4i)]; err: <nil>

func EnvOrDefault added in v1.2.0 

func EnvOrDefault[T internal.EnvParsable](key string, defaultVal T, options ...option.Option) T

EnvOrDefault retrieves the value of the environment variable named by the key. If the variable is present in the environment the value will be parsed and returned. Otherwise, the default value will be returned. The value returned will be of the same type as the default value.

Example 
package main

import (
	"fmt"
	"net"
	"net/url"
	"os"
	"time"

	"github.com/obalunenko/getenv"
	"github.com/obalunenko/getenv/option"
)

func main() {
	const (
		key = "GH_GETENV_TEST"
	)

	defer func() {
		if err := os.Unsetenv(key); err != nil {
			panic(err)
		}
	}()

	var val any

	// string
	if err := os.Setenv(key, "golly"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, "golly")
	fmt.Printf("[%T]: %v\n", val, val)

	// int
	if err := os.Setenv(key, "123"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, -99)
	fmt.Printf("[%T]: %v\n", val, val)

	// time.Time
	if err := os.Setenv(key, "2022-01-20"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key,
		time.Date(1992, 12, 1, 0, 0, 0, 0, time.UTC),
		option.WithTimeLayout("2006-01-02"),
	)
	fmt.Printf("[%T]: %v\n", val, val)

	// []float64
	if err := os.Setenv(key, "26.89,0.67"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, []float64{-99},
		option.WithSeparator(","),
	)
	fmt.Printf("[%T]: %v\n", val, val)

	// time.Duration
	if err := os.Setenv(key, "2h35m"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, time.Second)
	fmt.Printf("[%T]: %v\n", val, val)

	// url.URL
	if err := os.Setenv(key, "https://test:abcd123@golangbyexample.com:8000/tutorials/intro?type=advance&compact=false#history"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, url.URL{})
	fmt.Printf("[%T]: %v\n", val, val)

	// net.IP
	if err := os.Setenv(key, "2001:cb8::17"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, net.IP{})
	fmt.Printf("[%T]: %v\n", val, val)

	// []string
	if err := os.Setenv(key, "a,b,c,d"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, []string{}, option.WithSeparator(","))
	fmt.Printf("[%T]: %v\n", val, val)

	// complex128
	if err := os.Setenv(key, "1+2i"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, complex128(0))
	fmt.Printf("[%T]: %v\n", val, val)

	// []complex64
	if err := os.Setenv(key, "1+2i,3+4i"); err != nil {
		panic(err)
	}

	val = getenv.EnvOrDefault(key, []complex64{}, option.WithSeparator(","))
	fmt.Printf("[%T]: %v\n", val, val)

}

Output:

[string]: golly
[int]: 123
[time.Time]: 2022-01-20 00:00:00 +0000 UTC
[[]float64]: [26.89 0.67]
[time.Duration]: 2h35m0s
[url.URL]: {https  test:abcd123 golangbyexample.com:8000 /tutorials/intro  false false type=advance&compact=false history }
[net.IP]: 2001:cb8::17
[[]string]: [a b c d]
[complex128]: (1+2i)
[[]complex64]: [(1+2i) (3+4i)]

Types

This section is empty.

Source Files

View all Source files

Directories

Path Synopsis
Package internal provides internal implementation logic for environment variables parsing.
 Package internal provides internal implementation logic for environment variables parsing.
Package option provides options for parsing environment variables.
 Package option provides options for parsing environment variables.

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