From ef740512ca31c521e31b632b9840933717643f22 Mon Sep 17 00:00:00 2001
From: Hector <dev@hsmith.org>
Date: Sun, 29 Aug 2021 12:21:44 +0100
Subject: [PATCH] db and socket paths are now optional

When running the exporter at least one path is required (db, or socket),
but not both.
When one of the paths is not provided, the metrics that correspond to that
source are not exporter. For example, if the database path is not set, the
database metrics will not be shown.
At least one path is required. Startup will fail if neither path provided.
---
 src/exporter.go | 41 ++++++++++++++++++++++++++---------------
 1 file changed, 26 insertions(+), 15 deletions(-)

diff --git a/src/exporter.go b/src/exporter.go
index 93cdec5..5d568c3 100644
--- a/src/exporter.go
+++ b/src/exporter.go
@@ -64,21 +64,29 @@ type Exporter struct {
 }
 
 func (e *Exporter) Describe(ch chan<- *prometheus.Desc) {
-	ch <- metricUp
-	ch <- metricBadIpsPerJail
-	ch <- metricBannedIpsPerJail
-	ch <- metricEnabledJails
-	ch <- metricErrorCount
-	ch <- metricServerPing
+	if e.db != nil {
+		ch <- metricUp
+		ch <- metricBadIpsPerJail
+		ch <- metricBannedIpsPerJail
+		ch <- metricEnabledJails
+		ch <- metricErrorCount
+	}
+	if e.socket != nil {
+		ch <- metricServerPing
+	}
 }
 
 func (e *Exporter) Collect(ch chan<- prometheus.Metric) {
-	e.collectBadIpsPerJailMetrics(ch)
-	e.collectBannedIpsPerJailMetrics(ch)
-	e.collectEnabledJailMetrics(ch)
-	e.collectUpMetric(ch)
-	e.collectErrorCountMetric(ch)
-	e.collectServerPingMetric(ch)
+	if e.db != nil {
+		e.collectBadIpsPerJailMetrics(ch)
+		e.collectBannedIpsPerJailMetrics(ch)
+		e.collectEnabledJailMetrics(ch)
+		e.collectUpMetric(ch)
+		e.collectErrorCountMetric(ch)
+	}
+	if e.socket != nil {
+		e.collectServerPingMetric(ch)
+	}
 }
 
 func (e *Exporter) collectUpMetric(ch chan<- prometheus.Metric) {
@@ -168,9 +176,12 @@ func main() {
 	} else {
 		log.Print("starting fail2ban exporter")
 
-		exporter := &Exporter{
-			db:     fail2banDb.MustConnectToDb(appSettings.Fail2BanDbPath),
-			socket: socket.MustConnectToSocket(appSettings.Fail2BanSocketPath),
+		exporter := &Exporter{}
+		if appSettings.Fail2BanDbPath != "" {
+			exporter.db = fail2banDb.MustConnectToDb(appSettings.Fail2BanDbPath)
+		}
+		if appSettings.Fail2BanSocketPath != "" {
+			exporter.socket = socket.MustConnectToSocket(appSettings.Fail2BanSocketPath)
 		}
 		prometheus.MustRegister(exporter)