Add access format support for Elasticsearch notification target (#4006)

This change adds `access` format support for notifications to a
Elasticsearch server, and it refactors `namespace` format support.

In the case of `access` format, for each event in Minio, a JSON
document is inserted into Elasticsearch with its timestamp set to the
event's timestamp, and with the ID generated automatically by
elasticsearch. No events are modified or deleted in this mode.

In the case of `namespace` format, for each event in Minio, a JSON
document is keyed together by the bucket and object name is updated in
Elasticsearch. In the case of an object being created or over-written
in Minio, a new document or an existing document is inserted into the
Elasticsearch index. If an object is deleted in Minio, the
corresponding document is deleted from the Elasticsearch index.

Additionally, this change upgrades Elasticsearch support to the 5.x
series. This is a breaking change, and users of previous elasticsearch
versions should upgrade.

Also updates documentation on Elasticsearch notification target usage
and has a link to an elasticsearch upgrade guide.

This is the last patch that finally resolves #3928.

cmd/notify-elasticsearch.go

@@ -17,14 +17,20 @@
 package cmd
 
 import (
-	"encoding/hex"
-	"errors"
+	"context"
 	"fmt"
 	"io/ioutil"
+	"time"
 
 	"github.com/Sirupsen/logrus"
-	"github.com/minio/sha256-simd"
-	"gopkg.in/olivere/elastic.v3"
+	"gopkg.in/olivere/elastic.v5"
+)
+
+var (
+	esErrFunc = newNotificationErrorFactory("Elasticsearch")
+
+	errESFormat = esErrFunc(`"format" value is invalid - it must be one of "%s" or "%s".`, formatNamespace, formatAccess)
+	errESIndex  = esErrFunc("Index name was not specified in the configuration.")
 )
 
 // elasticQueue is a elasticsearch event notification queue.
@@ -39,14 +45,15 @@ func (e *elasticSearchNotify) Validate() error {
 	if !e.Enable {
 		return nil
 	}
-	if e.Format != formatNamespace {
-		return fmt.Errorf(
-			"Elasticsearch Notifier Error: \"format\" must be \"%s\"",
-			formatNamespace)
+	if e.Format != formatNamespace && e.Format != formatAccess {
+		return errESFormat
 	}
 	if _, err := checkURL(e.URL); err != nil {
 		return err
 	}
+	if e.Index == "" {
+		return errESIndex
+	}
 	return nil
 }
 
@@ -60,15 +67,11 @@ func dialElastic(esNotify elasticSearchNotify) (*elastic.Client, error) {
 	if !esNotify.Enable {
 		return nil, errNotifyNotEnabled
 	}
-	client, err := elastic.NewClient(
+	return elastic.NewClient(
 		elastic.SetURL(esNotify.URL),
 		elastic.SetSniff(false),
 		elastic.SetMaxRetries(10),
 	)
-	if err != nil {
-		return nil, err
-	}
-	return client, nil
 }
 
 func newElasticNotify(accountID string) (*logrus.Logger, error) {
@@ -77,23 +80,26 @@ func newElasticNotify(accountID string) (*logrus.Logger, error) {
 	// Dial to elastic search.
 	client, err := dialElastic(esNotify)
 	if err != nil {
-		return nil, err
+		return nil, esErrFunc("Error dialing the server: %v", err)
 	}
 
 	// Use the IndexExists service to check if a specified index exists.
-	exists, err := client.IndexExists(esNotify.Index).Do()
+	exists, err := client.IndexExists(esNotify.Index).
+		Do(context.Background())
 	if err != nil {
-		return nil, err
+		return nil, esErrFunc("Error checking if index exists: %v", err)
 	}
 	// Index does not exist, attempt to create it.
 	if !exists {
 		var createIndex *elastic.IndicesCreateResult
-		createIndex, err = client.CreateIndex(esNotify.Index).Do()
+		createIndex, err = client.CreateIndex(esNotify.Index).
+			Do(context.Background())
 		if err != nil {
-			return nil, err
+			return nil, esErrFunc("Error creating index `%s`: %v",
+				esNotify.Index, err)
 		}
 		if !createIndex.Acknowledged {
-			return nil, errors.New("Index not created")
+			return nil, esErrFunc("Index not created")
 		}
 	}
 
@@ -118,7 +124,7 @@ func newElasticNotify(accountID string) (*logrus.Logger, error) {
 }
 
 // Fire is required to implement logrus hook
-func (q elasticClient) Fire(entry *logrus.Entry) error {
+func (q elasticClient) Fire(entry *logrus.Entry) (err error) {
 	// Reflect on eventType and Key on their native type.
 	entryStr, ok := entry.Data["EventType"].(string)
 	if !ok {
@@ -129,25 +135,44 @@ func (q elasticClient) Fire(entry *logrus.Entry) error {
 		return nil
 	}
 
-	// Calculate a unique key id. Choosing sha256 here.
-	shaKey := sha256.Sum256([]byte(keyStr))
-	keyStr = hex.EncodeToString(shaKey[:])
-
-	// If event matches as delete, we purge the previous index.
-	if eventMatch(entryStr, []string{"s3:ObjectRemoved:*"}) {
-		_, err := q.Client.Delete().Index(q.params.Index).
-			Type("event").Id(keyStr).Do()
-		if err != nil {
-			return err
+	switch q.params.Format {
+	case formatNamespace:
+		// If event matches as delete, we purge the previous index.
+		if eventMatch(entryStr, []string{"s3:ObjectRemoved:*"}) {
+			_, err = q.Client.Delete().Index(q.params.Index).
+				Type("event").Id(keyStr).Do(context.Background())
+			break
+		} // else we update elastic index or create a new one.
+		_, err = q.Client.Index().Index(q.params.Index).
+			Type("event").
+			BodyJson(map[string]interface{}{
+				"Records": entry.Data["Records"],
+			}).Id(keyStr).Do(context.Background())
+	case formatAccess:
+		// eventTime is taken from the first entry in the
+		// records.
+		events, ok := entry.Data["Records"].([]NotificationEvent)
+		if !ok {
+			return esErrFunc("Unable to extract event time due to conversion error of entry.Data[\"Records\"]=%v", entry.Data["Records"])
 		}
-		return nil
-	} // else we update elastic index or create a new one.
-	_, err := q.Client.Index().Index(q.params.Index).
-		Type("event").
-		BodyJson(map[string]interface{}{
-			"Records": entry.Data["Records"],
-		}).Id(keyStr).Do()
-	return err
+		var eventTime time.Time
+		eventTime, err = time.Parse(timeFormatAMZ, events[0].EventTime)
+		if err != nil {
+			return esErrFunc("Unable to parse event time \"%s\": %v",
+				events[0].EventTime, err)
+		}
+		// Extract event time in milliseconds for Elasticsearch.
+		eventTimeStr := fmt.Sprintf("%d", eventTime.UnixNano()/1000000)
+		_, err = q.Client.Index().Index(q.params.Index).Type("event").
+			Timestamp(eventTimeStr).
+			BodyJson(map[string]interface{}{
+				"Records": entry.Data["Records"],
+			}).Do(context.Background())
+	}
+	if err != nil {
+		return esErrFunc("Error inserting/deleting entry: %v", err)
+	}
+	return nil
 }
 
 // Required for logrus hook implementation