uconfig-watchfiles

File watching extension for uconfig. Add watchfiles.New() to your plugins and call Watch for automatic config reload when source files change.

Usage

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"os"
	"os/signal"

	"github.com/omeid/uconfig"
	"github.com/omeid/uconfig/plugins/file"

	watchfiles "github.com/omeid/uconfig-watchfiles"
)

type Config struct {
	Hosts []string `default:"localhost" usage:"bind addresses"`
	Mode  string   `default:"start" flag:",command" usage:"start|stop"`
}

var files = uconfig.Files{
	{Path: file.Relative("config.json"), Unmarshal: json.Unmarshal, Optional: true},
}

func main() {
	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
	defer cancel()

	conf := uconfig.Classic[Config](files, watchfiles.New())

	err := conf.Watch(ctx, func(ctx context.Context, c *Config) error {
		fmt.Printf("config loaded: %+v\n", c)

		// Block until told to reload or stop.
		<-ctx.Done()
		return nil

		// Return nil to exit Watch cleanly.
		// Return any other error to abort.
	})

	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
}

The callback is called once with the initial config, then again whenever a config file changes. Changes are debounced (200ms). When a file changes, the callback's context is cancelled, the full config is re-parsed (preserving env, flags, and other sources), and the callback is called again with the new value.

watchfiles.New() is a uconfig Extension plugin. It discovers file paths from sibling file plugins and watches them with fsnotify. One watcher handles all files.

Install

go get github.com/omeid/uconfig-watchfiles

LICENSE

MIT.