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
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 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)]