Go: Handling HUP signal - reloading configuration settings while running

sighup.go

package main

import (
  "bufio"
  "fmt"
  "log"
  "os"
  "os/signal"
  "sync"
  "syscall"
  "time"
)

type Config struct {
  sync.Mutex
  files []string
}

func (c *Config) Init() {
  c.Lock()
  defer c.Unlock()
  f, err := os.Open("config")
  if err != nil {
    log.Fatal(err)
  }
  c.files = make([]string, 0)
  scanner := bufio.NewScanner(f)
  for scanner.Scan() {
    c.files = append(c.files, scanner.Text())
  }
}

func main() {
  config := &Config{}
  config.Init()

  go func() {
    sigHUP := make(chan os.Signal, 1)
    signal.Notify(sigHUP, syscall.SIGHUP)

    for {
      select {
      case <-sigHUP:
        config.Init()
      }
    }
  }()

  ticker := time.NewTicker(time.Second * 5)
  for {
    select {
    case <-ticker.C:
      //Note: access to config.files here is not concurrent safe (you will get a incomplete copy of it when reading at the same time as an update is happening), but it is used here purely for simplicities sake. It is unlikely your application will need to constantly read the configuration data in like this and will instead use it one time after it has been read in to start your main application..
      fmt.Println("Files available:", config.files)
    }
  }
}