From 7fca924edb5c1ecfdf7b89c44c43dec30056989e Mon Sep 17 00:00:00 2001
From: Jaime Soriano Pastor <jaime.soriano@elastic.co>
Date: Sun, 2 Dec 2018 11:10:19 +0100
Subject: [PATCH] Log dropped events at the debug level (#9251)

Log events dropped by encoding problems at the debug level.

(cherry picked from commit 1180b37d80c2fda445195374bcf09ed9cc4b2f83)
---
 CHANGELOG.asciidoc                      | 1 +
 libbeat/outputs/console/console.go      | 1 +
 libbeat/outputs/elasticsearch/client.go | 1 +
 libbeat/outputs/fileout/file.go         | 1 +
 libbeat/outputs/kafka/client.go         | 1 +
 libbeat/outputs/logstash/enc.go         | 8 ++++++--
 libbeat/outputs/redis/client.go         | 2 ++
 7 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.asciidoc b/CHANGELOG.asciidoc
index f20783cd5b8..0244193fd05 100644
--- a/CHANGELOG.asciidoc
+++ b/CHANGELOG.asciidoc
@@ -34,6 +34,7 @@ https://github.com/elastic/beats/compare/v6.5.1...6.5[Check the HEAD diff]
 *Affecting all Beats*
 
 - Propagate Sync error when running SafeFileRotate. {pull}9069[9069]
+- Log events at the debug level when dropped by encoding problems. {pull}9251[9251]
 
 *Auditbeat*
 
diff --git a/libbeat/outputs/console/console.go b/libbeat/outputs/console/console.go
index 7958b8da6bd..15d317c5159 100644
--- a/libbeat/outputs/console/console.go
+++ b/libbeat/outputs/console/console.go
@@ -129,6 +129,7 @@ func (c *console) publishEvent(event *publisher.Event) bool {
 		}
 
 		logp.Critical("Unable to encode event: %v", err)
+		logp.Debug("console", "Failed event: %v", event)
 		return false
 	}
 
diff --git a/libbeat/outputs/elasticsearch/client.go b/libbeat/outputs/elasticsearch/client.go
index 2bd1c06ab37..f9d13388233 100644
--- a/libbeat/outputs/elasticsearch/client.go
+++ b/libbeat/outputs/elasticsearch/client.go
@@ -372,6 +372,7 @@ func bulkEncodePublishRequest(
 		}
 		if err := body.Add(meta, event); err != nil {
 			logp.Err("Failed to encode event: %s", err)
+			logp.Debug("elasticsearch", "Failed event: %v", event)
 			continue
 		}
 		okEvents = append(okEvents, data[i])
diff --git a/libbeat/outputs/fileout/file.go b/libbeat/outputs/fileout/file.go
index 75ea3092463..1b05fbb783f 100644
--- a/libbeat/outputs/fileout/file.go
+++ b/libbeat/outputs/fileout/file.go
@@ -126,6 +126,7 @@ func (out *fileOutput) Publish(
 			} else {
 				logp.Warn("Failed to serialize the event: %v", err)
 			}
+			logp.Debug("file", "Failed event: %v", event)
 
 			dropped++
 			continue
diff --git a/libbeat/outputs/kafka/client.go b/libbeat/outputs/kafka/client.go
index cae9c262eb5..a1f1955ff9c 100644
--- a/libbeat/outputs/kafka/client.go
+++ b/libbeat/outputs/kafka/client.go
@@ -179,6 +179,7 @@ func (c *client) getEventMessage(data *publisher.Event) (*message, error) {
 
 	serializedEvent, err := c.codec.Encode(c.index, event)
 	if err != nil {
+		logp.Debug("kafka", "Failed event: %v", event)
 		return nil, err
 	}
 
diff --git a/libbeat/outputs/logstash/enc.go b/libbeat/outputs/logstash/enc.go
index 00cb304c646..17d24d7a69c 100644
--- a/libbeat/outputs/logstash/enc.go
+++ b/libbeat/outputs/logstash/enc.go
@@ -24,7 +24,11 @@ import (
 
 func makeLogstashEventEncoder(info beat.Info, escapeHTML bool, index string) func(interface{}) ([]byte, error) {
 	enc := json.New(false, escapeHTML, info.Version)
-	return func(event interface{}) ([]byte, error) {
-		return enc.Encode(index, event.(*beat.Event))
+	return func(event interface{}) (d []byte, err error) {
+		d, err = enc.Encode(index, event.(*beat.Event))
+		if err != nil {
+			debugf("Failed to encode event: %v", event)
+		}
+		return
 	}
 }
diff --git a/libbeat/outputs/redis/client.go b/libbeat/outputs/redis/client.go
index fc395070e27..7238ba367fd 100644
--- a/libbeat/outputs/redis/client.go
+++ b/libbeat/outputs/redis/client.go
@@ -312,6 +312,7 @@ func serializeEvents(
 		serializedEvent, err := codec.Encode(index, &d.Content)
 		if err != nil {
 			logp.Err("Encoding event failed with error: %v", err)
+			logp.Debug("redis", "Failed event: %v", d.Content)
 			goto failLoop
 		}
 
@@ -329,6 +330,7 @@ failLoop:
 		serializedEvent, err := codec.Encode(index, &d.Content)
 		if err != nil {
 			logp.Err("Encoding event failed with error: %v", err)
+			logp.Debug("redis", "Failed event: %v", d.Content)
 			i++
 			continue
 		}