use errors.Is to check error

go.mod

@@ -13,6 +13,7 @@ require (
 	github.com/golang/groupcache v0.0.0-20191027212112-611e8accdfc9 // indirect
 	github.com/jinzhu/configor v1.2.1
 	github.com/patrickmn/go-cache v2.1.0+incompatible
+	github.com/pkg/errors v0.9.1
 	github.com/projecteru2/core v0.0.0-20210302082338-f44a0e05990c
 	github.com/prometheus/client_golang v1.8.0
 	github.com/sethvargo/go-signalcontext v0.1.0

selfmon/selfmon.go

@@ -5,21 +5,21 @@ import (
 	"io"
 	"os"
 	"os/signal"
-	"strings"
 	"sync"
 	"syscall"
 	"time"
 
+	"github.com/pkg/errors"
 	log "github.com/sirupsen/logrus"
 	etcdtypes "go.etcd.io/etcd/v3/clientv3"
 	"go.etcd.io/etcd/v3/mvcc/mvccpb"
 
+	"github.com/projecteru2/agent/types"
+	"github.com/projecteru2/agent/utils"
 	"github.com/projecteru2/core/client"
 	pb "github.com/projecteru2/core/rpc/gen"
 	coremeta "github.com/projecteru2/core/store/etcdv3/meta"
-
-	"github.com/projecteru2/agent/types"
-	"github.com/projecteru2/agent/utils"
+	coretypes "github.com/projecteru2/core/types"
 )
 
 // ActiveKey .
@@ -242,7 +242,7 @@ func (m *Selfmon) Register() (func(), error) {
 			}
 
 			if ne, un, err := m.register(); err != nil {
-				if !strings.Contains(err.Error(), "Key exists") {
+				if !errors.Is(err, coretypes.ErrKeyExists) {
 					log.Errorf("[Register] failed to re-register: %v", err)
 					time.Sleep(time.Second)
 					continue