autoconfig

Autonomous configuration for golang packages with hot reload.

• Each package has its own configuration section within a single global config file, neither main() nor any other part of your application has the knowledge of the package configuration.
• Config can be dynamically updated when the application receives a signal.

Supported file format are :

• INI (using https://github.com/go-ini/ini)
• YAML (using https://gopkg.in/yaml.v2)

Usage (YAML)

Init :

autoconfig.Load(yaml.New(filename))
autoconfig.ReloadOn(syscall.SIGHUP)

Sample config file :

[...]

section_name:
  group:
    value: foobar

[...]

Package config :

package mypackage

type GroupConfig struct {
	Value `yaml:"value"`
}

type PkgConf struct {
	Group GroupConfig `yaml:"group"`
}

func (c *PkgConf) Changed() {
	// Do something when config has changed
}

var (
  // config, with default values
	pkfCong = PkgConf{
		Group: GroupConfig{
			Value: "default value",
		},
	}
	_ = autoconfig.Register("section_name", &pkgConf)
)

Instance config :

package mypackage

var (
	// Set defaults
	_ = autoconfig.Register("section_name", &PkgConf{
		Group: GroupConfig{
			Value: "default value",
		},
	})
)

type PkgClass struct {}

func New() *PkgClass {
	n := &PkgClass{}
	// This will trigger a n.Reconfigure() call with the current config
	autoconfig.Reconfigure("section_name", n)
	return n
}

func (c *PkgClass) Reconfigure(c interface{}) {
	if cfg, ok := c.(*PkgConf); ok {
		// Do something when config has changed
	}
}

autoconfig will cleanly Lock/Unlock your structs provided they implement sync.Locker

Usage (INI)

Init :

autoconfig.Load(ini.New(filename))
autoconfig.ReloadOn(syscall.SIGHUP)

Sample config file :

[...]

[section_name]
value=foobar

[...]

Package config :

package mypackage

type PkgConf struct {
	Value string `ini:"value"`
}

var (
	pkfCong = PkgConf{
		Value: "default value",
	}
	_ = autoconfig.Register("section_name", &pkgConf)
)

Other file formats

Any config file format can be used, provided a loader class implementing the Loader interface is provided :

type Loader interface {
	Load(map[string]interface{}) error
}

Caveats

• Only a single config file is supported,
• Values types are supported only if the underlying format supports them (e.g. INI does not support slices).

TODO

• Multiple files

License

MIT - see LICENSE