consul-catalogを使って監視しているserviceのNode自体に変更があったことを検知する

main.go

package main

import (
	"encoding/json"
	"github.com/mizzy/consul-catalog"
	"log"
	"os"
	"reflect"
	"time"
)

func main() {
	client, err := consulcatalog.NewClient(consulcatalog.DefaultConfig())
	if err != nil {
		log.Fatalln(err)
	}
	var index uint64
	var nodes consulcatalog.Nodes
	service := os.Args[1]
	for {
		log.Printf("Get blocking query service %s index %d ...", service, index)
		meta, newNodes, err := client.Get("service", service, index)
		if err != nil {
			log.Printf("error: %s", err)
			time.Sleep(5 * time.Second)
			continue
		}
		log.Printf("new index: %v", meta.ModifyIndex)
		index = meta.ModifyIndex
		if reflect.DeepEqual(nodes, newNodes) {
			log.Println("no Nodes changed.")
		} else {
			jsonBytes, _ := json.Marshal(newNodes)
			log.Printf("Nodes changed. %s", jsonBytes)
			nodes = newNodes
		}
	}
}