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)]