env
import "github.com/halorium/env"
Usage
Set some environment variables:
export TEST_STRING="some value"
export TEST_BOOL=true
export TEST_INT=1
export TEST_FLOAT=1.2
export TEST_DURATION="5s"
export TEST_LIST="one,two,three"
export TEST_MAP="one:1,two:2,three:3"
Write some code:
package main
import (
"fmt"
"log"
"time"
"github.com/halorium/env"
)
type Config struct {
StringField string `env:"TEST_STRING"`
BoolField bool `env:"TEST_BOOL"`
IntField int `env:"TEST_INT"`
FloatField float64 `env:"TEST_FLOAT"`
DurationField time.Duration `env:"TEST_DURATION"`
ListField []string `env:"TEST_LIST"`
MapField map[string]int `env:"TEST_MAP"`
}
func (c Config) String() string {
val := fmt.Sprintf(
"StringField:'%s'\nBoolField:'%v'\nIntField:'%d'\nFloatField:'%f'\nDurationField:'%s'\n",
c.StringField,
c.BoolField,
c.IntField,
c.FloatField,
c.DurationField)
val += "ListField:\n " + strings.Join(c.ListField, " \n") + "\n"
val += "MapField:\n"
for k, v := range c.MapField {
val += fmt.Sprintf(" %s: %d\n", k, v)
}
return val
}
func main() {
var cfg Config
err := env.Unmarshal(&cfg)
if err != nil {
log.Fatal(err)
}
fmt.Println(cfg)
}
Results:
todo
Struct Tags
The default tag is 'env' however this can be changed in the options.
Example:
type Config struct {
StringField string `custom:"TEST_STRING"`
BoolField bool `custom:"TEST_BOOL"`
IntField int `custom:"TEST_INT"`
FloatField float64 `custom:"TEST_FLOAT"`
DurationField time.Duration `custom:"TEST_DURATION"`
ListField []string `custom:"TEST_LIST"`
MapField map[string]int `custom:"TEST_MAP"`
}
var cfg Config
options := env.Options{Tag: "custom"}
err := env.Unmarshal(&cfg, options)
if err != nil {
log.Fatal(err)
}
fmt.Println(cfg)
Validation
env doesn't assume any validation, if an environment variable is not found then it is skipped.
The 'Required' option can be set to have an error returned if any environment variables are not set. Example:
var cfg Config
options := env.Options{Required: true}
err := env.Unmarshal(&cfg, options)
if err != nil {
log.Fatal(err)
}
fmt.Println(cfg)
Ignored Fields
env will ignore the field if the tag is set to either an empty string '' or a hyphen '-'. Example:
type Config struct {
StringField string `env:"TEST_STRING"`
BoolField bool `env:""` // ignored
IntField int `env:"-"` // ignored
}
Supported Field Types
- string
- int8, int16, int32, int64
- bool
- float32, float64
- slices of any supported type
- maps (keys and values of any supported type)
- time.Duration
Note: Embedded structs using these fields are also supported.
Custom Unmarshaler
Any field whose type (or pointer-to-type) implements env.UnmarshalENV can control its own deserialization:
export IP=127.0.0.1
type CustomIP net.IP
func (c *CustomIP) UnmarshalENV(v string) error {
*c = CustomIP(net.ParseIP(v))
return nil
}
type Config struct {
IP CustomIP `env:"IP"`
}
Other Ways to Use 'env'
env implements helper functions if you simply want to get environment variables as a specified type.
s, err := env.AsString("TEST_STRING") // returns (string, error)
b, err := env.AsBool("TEST_BOOL") // returns (bool, error)
i, err := env.AsInt("TEST_INT", 64) // returns (int64, error)
i, err := env.AsUint("TEST_UINT", 64) // returns (uint64, error)
f, err := env.AsFloat("TEST_FLOAT", 64) // returns (float64, error)
d, err := env.AsDuration("TEST_DURATION") // returns (time.Duration, error)
