Etcd 3.4.3 breaking case.

main.go

package main

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"log"
	"time"

	"go.etcd.io/etcd/clientv3"
	"github.com/google/uuid"
)

const printFreq = 100

func main() {
	var endpoint string

	flag.StringVar(&endpoint, "endpoint", "http://localhost:2379", "etcd to connect to")
	flag.Parse()

	endpoints := []string{endpoint}

	cfg := clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: 5 * time.Second,
	}
	opsChan := make(chan int, 50)
	for i := 0; i < 10; i++ {
		go func() {
			etcdCl, err := clientv3.New(cfg)
			if err != nil {
				log.Fatalf("%v", err)
			}

			ops := 0
			for {
				err = putAndExpire(etcdCl)
				if err != nil {
					fmt.Printf("err: %v\n", err)
				}
				ops++
				if ops%printFreq == 0 {
					opsChan <- printFreq
				}
			}
		}()
	}
	ticker := time.NewTicker(5 * time.Second)
	totalOps := 0
	for {
		select {
		case o := <-opsChan:
			totalOps += o
		case <-ticker.C:
			fmt.Printf("%.00f put+get+expires/s\n", float64(totalOps)/5.0)
			totalOps = 0
		}
	}
}

func putAndExpire(etcdCl *clientv3.Client) error {
	ctx := context.Background()

	tranBytes, _ := uuid.NewRandom()
	key := tranBytes.String()

	contentBytes, _ := uuid.NewRandom()
	content := contentBytes.String()

	lease, err := etcdCl.Grant(ctx, 30)
	if err != nil {
		return err
	}

	_, err = etcdCl.Put(ctx, key, content, clientv3.WithLease(lease.ID))
	if err != nil {
		return err
	}

	gr, err := etcdCl.Get(ctx, key)
	if err != nil {
		return err
	}

	if len(gr.Kvs) == 0 {
		return errors.New("no such key")
	}

	leaseID := gr.Kvs[0].Lease

	if leaseID == 0 {
		return errors.New("key not leased")
	}

	_, err = etcdCl.Revoke(ctx, clientv3.LeaseID(leaseID))

	if err != nil {
		return err
	}
	return nil
}