fig is a tiny library for loading an application's configuration into a Go struct.
- 🛠️ Define your configuration, validations and defaults all within a single struct.
- 🌍 Easily load your configuration from a file, the environment, or both.
- ⏰ Decode strings into
Time
,Duration
,Regexp
, or any custom type that satisfies theStringUnmarshaler
interface. - 🗂️ Compatible with
yaml
,json
, andtoml
file formats. - 🧩 Only three external dependencies.
$ go get -d github.com/kkyr/fig
Define your config file:
# config.yaml
build: "2020-01-09T12:30:00Z"
server:
ports:
- 8080
cleanup: 1h
logger:
level: "warn"
trace: true
Define your struct along with validations or defaults:
package main
import (
"fmt"
"github.com/kkyr/fig"
)
type Config struct {
Build time.Time `fig:"build" validate:"required"`
Server struct {
Host string `fig:"host" default:"127.0.0.1"`
Ports []int `fig:"ports" default:"[80,443]"`
Cleanup time.Duration `fig:"cleanup" default:"30m"`
}
Logger struct {
Level string `fig:"level" default:"info"`
Pattern *regexp.Regexp `fig:"pattern" default:".*"`
Trace bool `fig:"trace"`
}
}
func main() {
var cfg Config
err := fig.Load(&cfg)
// error handling omitted
fmt.Printf("%+v\n", cfg)
// {Build:2019-12-25T00:00:00Z Server:{Host:127.0.0.1 Ports:[8080] Cleanup:1h0m0s} Logger:{Level:warn Pattern:.* Trace:true}}
}
Fields marked as required are checked to ensure they're not empty, and default values are applied to fill in those that are empty.
By default, fig will only look for values in a config file. To also include values from the environment, use the UseEnv
option:
fig.Load(&cfg, fig.UseEnv("APP_PREFIX"))
In case of conflicts, values from the environment take precedence.
See usage examples.
For detailed documentation, visit go.dev.
PRs are welcome! Please explain your motivation for the change in your PR and ensure your change is properly tested and documented.