From a85bda5e49e24d141f8e4d3898aee9060b20bd88 Mon Sep 17 00:00:00 2001
From: cw-ozaki <log@logn.in>
Date: Wed, 22 Apr 2020 09:30:09 +0900
Subject: [PATCH] fixes panic appears when tailer is nil

---
 postfix_exporter.go | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/postfix_exporter.go b/postfix_exporter.go
index 2e2ec22..9a53c63 100644
--- a/postfix_exporter.go
+++ b/postfix_exporter.go
@@ -612,6 +612,9 @@ func NewPostfixExporter(showqPath string, logfilePath string, journal *Journal,
 func (e *PostfixExporter) Describe(ch chan<- *prometheus.Desc) {
 	ch <- postfixUpDesc
 
+	if e.tailer == nil {
+		return
+	}
 	ch <- e.cleanupProcesses.Desc()
 	ch <- e.cleanupRejects.Desc()
 	ch <- e.cleanupNotAccepted.Desc()
@@ -664,7 +667,7 @@ func (e *PostfixExporter) foreverCollectFromJournal(ctx context.Context) {
 func (e *PostfixExporter) StartMetricCollection(ctx context.Context) {
 	if e.journal != nil {
 		e.foreverCollectFromJournal(ctx)
-	} else {
+	} else if e.tailer != nil {
 		e.CollectLogfileFromFile(ctx)
 	}
 
@@ -697,6 +700,9 @@ func (e *PostfixExporter) Collect(ch chan<- prometheus.Metric) {
 			e.showqPath)
 	}
 
+	if e.tailer == nil {
+		return
+	}
 	ch <- e.cleanupProcesses
 	ch <- e.cleanupRejects
 	ch <- e.cleanupNotAccepted