lazy initializing es client of auditing

pkg/simple/client/auditing/elasticsearch/elasticsearch.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"fmt"
 	"strings"
+	"sync"
 	"time"
 
 	es5 "github.com/elastic/go-elasticsearch/v5"
@@ -29,17 +30,30 @@ import (
 	"kubesphere.io/kubesphere/pkg/simple/client/auditing"
 )
 
+const (
+	ElasticV5 = "5"
+	ElasticV6 = "6"
+	ElasticV7 = "7"
+)
+
 var json = jsoniter.ConfigCompatibleWithStandardLibrary
 
 type Elasticsearch struct {
-	c    client
+	host    string
-	opts struct {
+	version string
 	index   string
-	}
+
+	c   client
+	mux sync.Mutex
 }
 
 func (es *Elasticsearch) SearchAuditingEvent(filter *auditing.Filter, from, size int64,
 	sort string) (*auditing.Events, error) {
+
+	if err := es.loadClient(); err != nil {
+		return &auditing.Events{}, err
+	}
+
 	queryPart := parseToQueryPart(filter)
 	if sort == "" {
 		sort = "desc"
@@ -59,7 +73,7 @@ func (es *Elasticsearch) SearchAuditingEvent(filter *auditing.Filter, from, size
 		return nil, err
 	}
 	resp, err := es.c.ExSearch(&Request{
-		Index: es.opts.index,
+		Index: es.index,
 		Body:  bytes.NewBuffer(body),
 	})
 	if err != nil || resp == nil {
@@ -80,6 +94,11 @@ func (es *Elasticsearch) SearchAuditingEvent(filter *auditing.Filter, from, size
 }
 
 func (es *Elasticsearch) CountOverTime(filter *auditing.Filter, interval string) (*auditing.Histogram, error) {
+
+	if err := es.loadClient(); err != nil {
+		return &auditing.Histogram{}, err
+	}
+
 	if interval == "" {
 		interval = "15m"
 	}
@@ -105,7 +124,7 @@ func (es *Elasticsearch) CountOverTime(filter *auditing.Filter, interval string)
 		return nil, err
 	}
 	resp, err := es.c.ExSearch(&Request{
-		Index: es.opts.index,
+		Index: es.index,
 		Body:  bytes.NewBuffer(body),
 	})
 	if err != nil || resp == nil {
@@ -135,6 +154,11 @@ func (es *Elasticsearch) CountOverTime(filter *auditing.Filter, interval string)
 }
 
 func (es *Elasticsearch) StatisticsOnResources(filter *auditing.Filter) (*auditing.Statistics, error) {
+
+	if err := es.loadClient(); err != nil {
+		return &auditing.Statistics{}, err
+	}
+
 	queryPart := parseToQueryPart(filter)
 	aggName := "resources_count"
 	aggsPart := map[string]interface{}{
@@ -155,7 +179,7 @@ func (es *Elasticsearch) StatisticsOnResources(filter *auditing.Filter) (*auditi
 		return nil, err
 	}
 	resp, err := es.c.ExSearch(&Request{
-		Index: es.opts.index,
+		Index: es.index,
 		Body:  bytes.NewBuffer(body),
 	})
 	if err != nil || resp == nil {
@@ -180,63 +204,89 @@ func (es *Elasticsearch) StatisticsOnResources(filter *auditing.Filter) (*auditi
 }
 
 func NewClient(options *Options) (*Elasticsearch, error) {
+	es := &Elasticsearch{
+		host:    options.Host,
+		version: options.Version,
+		index:   fmt.Sprintf("%s*", options.IndexPrefix),
+	}
+
+	err := es.initEsClient(es.version)
+	return es, err
+}
+
+func (es *Elasticsearch) initEsClient(version string) error {
 	clientV5 := func() (*ClientV5, error) {
-		c, err := es5.NewClient(es5.Config{Addresses: []string{options.Host}})
+		c, err := es5.NewClient(es5.Config{Addresses: []string{es.host}})
 		if err != nil {
 			return nil, err
 		}
 		return (*ClientV5)(c), nil
 	}
 	clientV6 := func() (*ClientV6, error) {
-		c, err := es6.NewClient(es6.Config{Addresses: []string{options.Host}})
+		c, err := es6.NewClient(es6.Config{Addresses: []string{es.host}})
 		if err != nil {
 			return nil, err
 		}
 		return (*ClientV6)(c), nil
 	}
 	clientV7 := func() (*ClientV7, error) {
-		c, err := es7.NewClient(es7.Config{Addresses: []string{options.Host}})
+		c, err := es7.NewClient(es7.Config{Addresses: []string{es.host}})
 		if err != nil {
 			return nil, err
 		}
 		return (*ClientV7)(c), nil
 	}
 
-	var (
+	var err error
-		version = options.Version
+	switch version {
-		es      = Elasticsearch{}
+	case ElasticV5:
-		err     error
-	)
-	es.opts.index = fmt.Sprintf("%s*", options.IndexPrefix)
-
-	if options.Version == "" {
-		var c5 *ClientV5
-		if c5, err = clientV5(); err == nil {
-			if version, err = c5.Version(); err == nil {
-				es.c = c5
-			}
-		}
-	}
-	if err != nil {
-		return nil, err
-	}
-
-	switch strings.Split(version, ".")[0] {
-	case "5":
-		if es.c == nil {
 		es.c, err = clientV5()
-		}
+	case ElasticV6:
-	case "6":
 		es.c, err = clientV6()
-	case "7":
+	case ElasticV7:
 		es.c, err = clientV7()
+	case "":
+		es.c = nil
 	default:
-		err = fmt.Errorf("unsupported elasticsearch version %s", version)
+		err = fmt.Errorf("unsupported elasticsearch version %s", es.version)
 	}
+
+	return err
+}
+
+func (es *Elasticsearch) loadClient() error {
+
+	// Check if Elasticsearch client has been initialized.
+	if es.c != nil {
+		return nil
+	}
+
+	// Create Elasticsearch client.
+	es.mux.Lock()
+	defer es.mux.Unlock()
+
+	if es.c != nil {
+		return nil
+	}
+
+	c, e := es5.NewClient(es5.Config{Addresses: []string{es.host}})
+	if e != nil {
+		return e
+	}
+
+	version, err := (*ClientV5)(c).Version()
 	if err != nil {
-		return nil, err
+		return err
 	}
-	return &es, nil
+
+	v := strings.Split(version, ".")[0]
+	err = es.initEsClient(v)
+	if err != nil {
+		return err
+	}
+
+	es.version = v
+	return nil
 }
 
 func parseToQueryPart(f *auditing.Filter) interface{} {