From cb27acafe4624b020cc84743df7976dd58925f20 Mon Sep 17 00:00:00 2001
From: varas <jhvaras@gmail.com>
Date: Fri, 9 Jul 2021 16:15:34 +0200
Subject: [PATCH] feat: log truncated or dropped events

---
 internal/agent/agent.go | 54 ++++++++++++++++++++++++++++-------------
 1 file changed, 37 insertions(+), 17 deletions(-)

diff --git a/internal/agent/agent.go b/internal/agent/agent.go
index 0002a133f..b70b18036 100644
--- a/internal/agent/agent.go
+++ b/internal/agent/agent.go
@@ -96,7 +96,10 @@ type inventory struct {
 	needsCleanup bool
 }
 
-var alog = log.WithComponent("Agent")
+var (
+	alog  = log.WithComponent("Agent")
+	aclog = log.WithComponent("AgentContext")
+)
 
 // AgentContext defines the interfaces between plugins and the agent
 type AgentContext interface {
@@ -1002,20 +1005,38 @@ func (c *context) ActiveEntitiesChannel() chan string {
 }
 
 func (c *context) SendEvent(event sample.Event, entityKey entity.Key) {
-	if c.eventSender != nil {
-		// limits any string field larger than 4095 chars
-		if c.cfg.TruncTextValues {
-			event = metric.TruncateLength(event, metric.NRDBLimit)
-		}
+	if c.eventSender == nil {
+		aclog.
+			WithField("entity_key", entityKey.String()).
+			Warn("cannot send, event sender not set")
+		return
+	}
 
-		includeSample := c.shouldIncludeEvent(event)
-		if includeSample {
-			if err := c.eventSender.QueueEvent(event, entityKey); err != nil {
-				alog.WithField(
-					"entityKey", entityKey,
-				).WithError(err).Error("could not queue event")
-			}
-		}
+	// truncates string fields larger than 4095 chars
+	if c.cfg.TruncTextValues {
+		orig := event
+		event = metric.TruncateLength(event, metric.NRDBLimit)
+		aclog.
+			WithField("entity_key", entityKey.String()).
+			WithField("length", metric.NRDBLimit).
+			WithField("original", fmt.Sprintf("+%v", orig)).
+			WithField("truncated", fmt.Sprintf("+%v", event)).
+			Warn("event truncated to NRDB limit")
+	}
+
+	includeSample := c.shouldIncludeEvent(event)
+	if !includeSample {
+		aclog.
+			WithField("entity_key", entityKey.String()).
+			WithField("event", fmt.Sprintf("+%v", event)).
+			Debug("event excluded by metric matcher")
+		return
+	}
+
+	if err := c.eventSender.QueueEvent(event, entityKey); err != nil {
+		alog.WithField(
+			"entityKey", entityKey,
+		).WithError(err).Error("could not queue event")
 	}
 }
 
@@ -1069,15 +1090,14 @@ func (c *context) AddReconnecting(p Plugin) {
 
 // Reconnect invokes again all the plugins that have been registered with the AddReconnecting function
 func (c *context) Reconnect() {
-	aclog := log.WithComponent("AgentContext")
 	aclog.Debug("Invoking Run() on all the plugins registered for reconnection.")
 	c.reconnecting.Range(triggerAddReconnecting(aclog))
 }
 
 // triggerAddReconnecting is used with sync.Map.Range to iterate through all plugins and reconnect them
-func triggerAddReconnecting(aclog log.Entry) func(pluginID interface{}, plugin interface{}) bool {
+func triggerAddReconnecting(l log.Entry) func(pluginID interface{}, plugin interface{}) bool {
 	return func(pluginID, plugin interface{}) bool {
-		aclog.WithField("plugin", pluginID).Debug("Reconnecting plugin.")
+		l.WithField("plugin", pluginID).Debug("Reconnecting plugin.")
 		func(p Plugin) {
 			go p.Run()
 		}(plugin.(Plugin))