mini golang app to connect and return a message from consul kv

main.go

package main

import (
	"encoding/json"
	"net/http"

	consul "github.com/hashicorp/consul/api"
)

func getKVdata() *consul.KVPair {

	config := *consul.DefaultConfig()
	// config.Address = "127.0.0.1:8500"

	client, err := consul.NewClient(&config)
	if err != nil {
		panic(err)
	}

	kv := client.KV()

	cqo := &consul.QueryOptions{}
	cqo.AllowStale = true

	// Lookup a kvpair
	pair, _, err := kv.Get("appX/message", cqo)
	if err != nil {
		panic(err)
	}
	return pair
}

func HelloWorldHandler(w http.ResponseWriter, req *http.Request) {
	w.Header().Add("Content-Type", "application/json")
	kvp := getKVdata()

	msg := map[string]string{}
	msg["message"] = string(kvp.Value)

	enc := json.NewEncoder(w)
	enc.Encode(msg)
}

func main() {

	http.HandleFunc("/", HelloWorldHandler)
	http.ListenAndServe(":8080", nil)

}

there's intentionally no retry and no caching of values from the kv to test consul's stale data behaviour ;)

we can then see following in consul's log :

    2017/08/11 17:40:06 [DEBUG] http: Request GET /v1/kv/appX/message?stale= (139.211µs) from=127.0.0.1:60640
    2017/08/11 17:40:08 [DEBUG] http: Request GET /v1/kv/appX/message?stale= (169.881µs) from=127.0.0.1:60642

the ?stale= is important here