The highest tagged major version is
README
¶
env
Simple lib to parse envs to structs in Go.
Example
A very basic example:
package main
import (
"fmt"
"time"
"github.com/caarlos0/env"
)
type config struct {
Home string `env:"HOME"`
Port int `env:"PORT" envDefault:"3000"`
IsProduction bool `env:"PRODUCTION"`
Hosts []string `env:"HOSTS" envSeparator:":"`
Duration time.Duration `env:"DURATION"`
TempFolder string `env:"TEMP_FOLDER" envDefault:"${HOME}/tmp" envExpand:"true"`
}
func main() {
cfg := config{}
if err := env.Parse(&cfg); err != nil {
fmt.Printf("%+v\n", err)
}
fmt.Printf("%+v\n", cfg)
}
You can run it like this:
$ PRODUCTION=true HOSTS="host1:host2:host3" DURATION=1s go run main.go
{Home:/your/home Port:3000 IsProduction:true Hosts:[host1 host2 host3] Duration:1s}
Go modules
If you're using go modules, you can update to v5 by issuing the following command:
go get -u github.com/caarlos0/env/v5
Then, on your code, use github.com/caarlos0/env/v5 instead of
github.com/caarlos0/env as the import path.
Supported types and defaults
The following types are supported out of the box:
string*string[]stringbool*bool[]boolint*int[]intint8*int8[]int8int16[]int16*int16int32[]int32*int32int64[]int64*int64uint[]uint*uintuint8[]uint8*uint8uint16[]uint16*uint16uint32[]uint32*uint32uint64[]uint64*uint64float32*float32[]float32float64*float64[]float64string[]stringtime.Duration[]time.Durationencoding.TextUnmarshaler*encoding.TextUnmarshaler[]encoding.TextUnmarshaler[]*encoding.TextUnmarshalerurl.URL[]url.URL
You can also use/define a custom parser func for any other type you want.
If you set the envDefault tag for something, this value will be used in the
case of absence of it in the environment. If you don't do that AND the
environment variable is also not set, the zero-value
of the type will be used: empty for strings, false for bools,
0 for ints and so forth.
By default, slice types will split the environment value on ,; you can change
this behavior by setting the envSeparator tag.
If you set the envExpand tag, environment variables (either in ${var} or
$var format) in the string will be replaced according with the actual value
of the variable.
Unexported fields are ignored.
Custom Parser Funcs
If you have a type that is not supported out of the box by the lib, you are able
to use (or define) and pass custom parsers (and their associated reflect.Type)
to the env.ParseWithFuncs() function.
In addition to accepting a struct pointer (same as Parse()), this function
also accepts a env.CustomParsers arg that under the covers is a
map[reflect.Type]env.ParserFunc.
env also ships with some pre-built custom parser funcs for common types. You
can check them out here.
Required fields
The env tag option required (e.g., env:"tagKey,required") can be added
to ensure that some environment variable is set. In the example above,
an error is returned if the config struct is changed to:
type config struct {
Home string `env:"HOME"`
Port int `env:"PORT" envDefault:"3000"`
IsProduction bool `env:"PRODUCTION"`
Hosts []string `env:"HOSTS" envSeparator:":"`
SecretKey string `env:"SECRET_KEY,required"`
}
Documentation
¶
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
var ( // ErrNotAStructPtr is returned if you pass something that is not a pointer to a // Struct to Parse ErrNotAStructPtr = errors.New("env: expected a pointer to a Struct") )
nolint: gochecknoglobals
Functions ¶
func Parse ¶
func Parse(v interface{}) error
Parse parses a struct containing `env` tags and loads its values from environment variables.
Example ¶
type inner struct {
Foo string `env:"FOO" envDefault:"foobar"`
}
type config struct {
Home string `env:"HOME,required"`
Port int `env:"PORT" envDefault:"3000"`
IsProduction bool `env:"PRODUCTION"`
Inner inner
}
os.Setenv("HOME", "/tmp/fakehome")
var cfg config
if err := Parse(&cfg); err != nil {
fmt.Println("failed:", err)
}
fmt.Printf("%+v", cfg)
Output: {Home:/tmp/fakehome Port:3000 IsProduction:false Inner:{Foo:foobar}}
func ParseWithFuncs ¶
func ParseWithFuncs(v interface{}, funcMap CustomParsers) error
ParseWithFuncs is the same as `Parse` except it also allows the user to pass in custom parsers.
Example ¶
type config struct {
ExampleURL url.URL `env:"EXAMPLE_URL" envDefault:"https://google.com"`
}
var cfg config
if err := ParseWithFuncs(&cfg, CustomParsers{
parsers.URLType: parsers.URLFunc,
}); err != nil {
fmt.Println("failed:", err)
}
fmt.Println(cfg.ExampleURL.String())
Output: https://google.com
Types ¶
type CustomParsers ¶
type CustomParsers map[reflect.Type]ParserFunc
CustomParsers is a friendly name for the type that `ParseWithFuncs()` accepts
type ParserFunc ¶
ParserFunc defines the signature of a function that can be used within `CustomParsers`
Source Files
Directories